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Thapa BS, Flynn TM, Jensvold ZD, Kemner KM, Sladek MF, O'Loughlin EJ, Marshall CW. Effects of soluble electron shuttles on microbial iron reduction and methanogenesis. Appl Environ Microbiol 2025; 91:e0222224. [PMID: 40277367 DOI: 10.1128/aem.02222-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2024] [Accepted: 04/02/2025] [Indexed: 04/26/2025] Open
Abstract
In many aquatic and terrestrial ecosystems, iron (Fe) reduction by microorganisms is a key part of biogeochemical cycling and energy flux. The presence of redox-active electron shuttles in the environment potentially enables a phylogenetically diverse group of microbes to use insoluble iron as a terminal electron acceptor. We investigated the impact that different electron shuttles had on respiration, microbial physiology, and microbial ecology. We tested eight different electron shuttles, seven quinones and riboflavin, with redox potentials between 0.217 and -0.340 V. Fe(III) reduction coupled with acetate oxidation was observed with all shuttles. Once Fe(III) reduction began to plateau, a rapid increase in acetate consumption was observed and coincided with the onset of methane production, except in the incubations with the shuttle 9,10-anthraquinone-2-carboxylic acid (AQC). The rates of iron reduction, acetate consumption, methanogenesis, and the microbial communities varied significantly across the different shuttles independent of redox potential. In general, shuttles appeared to reduce the overall diversity of the community compared to no shuttle controls, but certain shuttles were exceptions to this trend. Geobacteraceae were the predominant taxonomic family in all enrichments except in the presence of AQC or 1,2-dihydroxyanthraquinone (AQZ), but each shuttle enriched a unique community significantly different from the no shuttle control conditions. This suggests that the presence of different redox-active electron shuttles can have a large influence on the microbial ecology and total carbon flux in the environment.IMPORTANCEIron is the fourth most abundant element in the Earth's crust, and the reduction of iron by microbes is an important component of global biogeochemical cycles. A phylogenetically diverse group of microbes is capable of conserving energy with oxidized iron as a terminal electron acceptor, but the environmental conditions favoring certain taxonomic clades in iron-reducing environments are unclear. One complicating factor often overlooked in small-scale enrichments is the influence of soluble, redox-active electron shuttles on the rate and microbial ecology of iron reduction. We tested the effects of eight different electron shuttles on microbial physiology and ecology in iron-reducing enrichments derived from a local wetland. Each electron shuttle varied the microbial activity and enriched for a microbial community distinct from the no shuttle control condition. Therefore, in complex subsurface environments with many redox-active compounds present, we propose electron shuttles as a reason for the coexistence of multiple clades of iron-reducing bacteria.
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Affiliation(s)
- Bhim Sen Thapa
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - Theodore M Flynn
- Biosciences Division, Argonne National Laboratory, Lemont, Illinois, USA
| | - Zena D Jensvold
- Biosciences Division, Argonne National Laboratory, Lemont, Illinois, USA
| | - Kenneth M Kemner
- Biosciences Division, Argonne National Laboratory, Lemont, Illinois, USA
| | - Margaret F Sladek
- Biosciences Division, Argonne National Laboratory, Lemont, Illinois, USA
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Wang J, Zhang Y, Zhou L, Gao Y, Li K, Sun S. Multiple effects of carbon, sulfur and iron on microbial mercury methylation in black-odorous sediments. ENVIRONMENTAL RESEARCH 2024; 263:120048. [PMID: 39313174 DOI: 10.1016/j.envres.2024.120048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Revised: 09/06/2024] [Accepted: 09/20/2024] [Indexed: 09/25/2024]
Abstract
Black-odorous sediments provide ideal conditions for microbial mercury methylation. However, the multiple effects of carbon, sulfur, and iron on the microbial methylmercury of mercury in black-odorous sediments remains unclear. In this study, we conducted mercury methylation experiments using sediments collected from organically contaminated water bodies, as well as black-odorous sediments simulated in the laboratory. The results showed that black-odorous sediments exhibit a high capacity for mercury methylation. By simulating the blackening and odorization process in sediments, it was confirmed that dissolved oxygen, organic matter and sulfide were the primary factors triggering the black-odorous phenomenon in sediments. Regarding the influence of key factors in sediments on methylmercury formation, the batch tests demonstrated that high concentrations of organics additions (above 200 mg/L) may reduce bacterial activity and weaken mercury methylation in sediments. Under five different iron-sulfur ratios, the concentrations of methylmercury in the black-odorous sediments showed an increasing trend, the ratio of 5.0 Fe/S exhibited the highest MeHg accumulation. The iron-sulfur ratio in the sediment had a significant effect on the mercury methylation process, which was mainly due to the competition between Fe2+ and Hg2+ for sulfide sites and the adsorption/coprecipitation of Hg2+ by FeS. These findings offer a potential avenue for further understanding and controlling mercury methylation, contributing to the mitigation of the potential threat of mercury pollution to the environment and human health.
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Affiliation(s)
- Jinting Wang
- School of Hydraulic and Environmental Engineering, Changsha University of Science and Technology, Changsha, China.
| | - Yan Zhang
- School of Hydraulic and Environmental Engineering, Changsha University of Science and Technology, Changsha, China
| | - Lean Zhou
- School of Hydraulic and Environmental Engineering, Changsha University of Science and Technology, Changsha, China
| | - Yang Gao
- School of Hydraulic and Environmental Engineering, Changsha University of Science and Technology, Changsha, China
| | - Kai Li
- School of Hydraulic and Environmental Engineering, Changsha University of Science and Technology, Changsha, China
| | - Shiquan Sun
- School of Hydraulic and Environmental Engineering, Changsha University of Science and Technology, Changsha, China; Key Laboratory of Dongting Lake Aquatic Eco-Environmental Control and Restoration of Hunan Province, Changsha, China.
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Hoagland B, Rasmussen KL, Singha K, Spear JR, Navarre-Sitchler A. Metal-oxide precipitation influences microbiome structure in hyporheic zones receiving acid rock drainage. Appl Environ Microbiol 2024; 90:e0198723. [PMID: 38391193 PMCID: PMC10952486 DOI: 10.1128/aem.01987-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 01/14/2024] [Indexed: 02/24/2024] Open
Abstract
Streams impacted by historic mining activity are characterized by acidic pH, unique microbial communities, and abundant metal-oxide precipitation, all of which can influence groundwater-surface water exchange. We investigate how metal-oxide precipitates and hyporheic mixing mediate the composition of microbial communities in two streams receiving acid-rock and mine drainage near Silverton, Colorado, USA. A large, neutral pH hyporheic zone facilitated the precipitation of metal particles/colloids in hyporheic porewaters. A small, low pH hyporheic zone, limited by the presence of a low-permeability, iron-oxyhydroxide layer known as ferricrete, led to the formation of steep geochemical gradients and high dissolved-metal concentrations. To determine how these two hyporheic systems influence microbiome composition, we installed well clusters and deployed in situ microcosms in each stream to sample porewaters and sediments for 16S rRNA gene sequencing. Results indicated that distinct hydrogeochemical conditions were present above and below the ferricrete in the low pH system. A positive feedback loop may be present in the low pH stream where microbially mediated precipitation of iron-oxides contributes to additional clogging of hyporheic pore spaces, separating abundant, iron-oxidizing bacteria (Gallionella spp.) above the ferricrete from rare, low-abundance bacteria below the ferricrete. Metal precipitates and colloids that formed in the neutral pH hyporheic zone were associated with a more diverse phylogenetic community of nonmotile, nutrient-cycling bacteria that may be transported through hyporheic pore spaces. In summary, biogeochemical conditions influence, and are influenced by, hyporheic mixing, which mediates the distribution of micro-organisms and, thus, the cycling of metals in streams receiving acid-rock and mine drainage. IMPORTANCE In streams receiving acid-rock and mine drainage, the abundant precipitation of iron minerals can alter how groundwater and surface water mix along streams (in what is known as the "hyporheic zone") and may shape the distribution of microbial communities. The findings presented here suggest that neutral pH streams with large, well-mixed hyporheic zones may harbor and transport diverse microorganisms attached to particles/colloids through hyporheic pore spaces. In acidic streams where metal oxides clog pore spaces and limit hyporheic exchange, iron-oxidizing bacteria may dominate and phylogenetic diversity becomes low. The abundance of iron-oxidizing bacteria in acid mine drainage streams has the potential to contribute to additional clogging of hyporheic pore spaces and the accumulation of toxic metals in the hyporheic zone. This research highlights the dynamic interplay between hydrology, geochemistry, and microbiology at the groundwater-surface water interface of acid mine drainage streams.
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Affiliation(s)
- Beth Hoagland
- Department of Geology and Geological Engineering, Hydrologic Science and Engineering Program, Colorado School of Mines, Golden, Colorado, USA
- S.S. Papadopulos & Associates, Inc., Rockville, Maryland, USA
| | - Kalen L. Rasmussen
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado, USA
| | - Kamini Singha
- Department of Geology and Geological Engineering, Hydrologic Science and Engineering Program, Colorado School of Mines, Golden, Colorado, USA
| | - John R. Spear
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado, USA
| | - Alexis Navarre-Sitchler
- Department of Geology and Geological Engineering, Hydrologic Science and Engineering Program, Colorado School of Mines, Golden, Colorado, USA
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Meier AB, Oppermann S, Drake HL, Schmidt O. The root zone of graminoids: A niche for H2-consuming acetogens in a minerotrophic peatland. Front Microbiol 2022; 13:978296. [PMID: 35992704 PMCID: PMC9391049 DOI: 10.3389/fmicb.2022.978296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Accepted: 07/19/2022] [Indexed: 11/13/2022] Open
Abstract
The importance of acetogens for H2 turnover and overall anaerobic degradation in peatlands remains elusive. In the well-studied minerotrophic peatland fen Schlöppnerbrunnen, H2-consuming acetogens are conceptualized to be largely outcompeted by iron reducers, sulfate reducers, and hydrogenotrophic methanogens in bulk peat soil. However, in root zones of graminoids, fermenters thriving on rhizodeposits and root litter might temporarily provide sufficient H2 for acetogens. In the present study, root-free peat soils from around the roots of Molinia caerulea and Carex rostrata (i.e., two graminoids common in fen Schlöpnnerbrunnen) were anoxically incubated with or without supplemental H2 to simulate conditions of high and low H2 availability in the fen. In unsupplemented soil treatments, H2 concentrations were largely below the detection limit (∼10 ppmV) and possibly too low for acetogens and methanogens, an assumption supported by the finding that neither acetate nor methane substantially accumulated. In the presence of supplemental H2, acetate accumulation exceeded CH4 accumulation in Molinia soil whereas acetate and methane accumulated equally in Carex soil. However, reductant recoveries indicated that initially, additional unknown processes were involved either in H2 consumption or the consumption of acetate produced by H2-consuming acetogens. 16S rRNA and 16S rRNA gene analyses revealed that potential acetogens (Clostridium, Holophagaceae), methanogens (Methanocellales, Methanobacterium), iron reducers (Geobacter), and physiologically uncharacterized phylotypes (Acidobacteria, Actinobacteria, Bacteroidetes) were stimulated by supplemental H2 in soil treatments. Phylotypes closely related to clostridial acetogens were also active in soil-free Molinia and Carex root treatments with or without supplemental H2. Due to pronounced fermentation activities, H2 consumption was less obvious in root treatments, and acetogens likely thrived on root organic carbon and fermentation products (e.g., ethanol) in addition to H2. Collectively, the data highlighted that in fen Schlöppnerbrunnen, acetogens are associated to graminoid roots and inhabit the peat soil around the roots, where they have to compete for H2 with methanogens and iron reducers. Furthermore, the study underscored that the metabolically flexible acetogens do not rely on H2, potentially a key advantage over other H2 consumers under the highly dynamic conditions characteristic for the root-zones of graminoids in peatlands.
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Affiliation(s)
- Anja B. Meier
- Department of Ecological Microbiology, University of Bayreuth, Bayreuth, Germany
| | - Sindy Oppermann
- Department of Ecological Microbiology, University of Bayreuth, Bayreuth, Germany
| | - Harold L. Drake
- Department of Ecological Microbiology, University of Bayreuth, Bayreuth, Germany
| | - Oliver Schmidt
- Department of Ecological Microbiology, University of Bayreuth, Bayreuth, Germany
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway
- *Correspondence: Oliver Schmidt,
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Yoshimi T, Fujii S, Oki H, Igawa T, Adams HR, Ueda K, Kawahara K, Ohkubo T, Hough MA, Sambongi Y. Crystal structure of thermally stable homodimeric cytochrome c'-β from Thermus thermophilus. Acta Crystallogr F Struct Biol Commun 2022; 78:217-225. [PMID: 35647678 PMCID: PMC9158659 DOI: 10.1107/s2053230x22005088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 05/11/2022] [Indexed: 11/10/2022] Open
Abstract
Cytochrome c'-β is a heme protein that belongs to the cytochrome P460 family and consists of homodimeric subunits with a predominantly antiparallel β-sheet fold. Here, the crystal structure of cytochrome c'-β from the thermophilic Thermus thermophilus (TTCP-β) is reported at 1.74 Å resolution. TTCP-β has a typical antiparallel β-sheet fold similar to that of cytochrome c'-β from the moderately thermophilic Methylococcus capsulatus (MCCP-β). The phenylalanine cap structure around the distal side of the heme is also similar in TTCP-β and MCCP-β, indicating that both proteins similarly bind nitric oxide and carbon monoxide, as observed spectroscopically. Notably, TTCP-β exhibits a denaturation temperature of 117°C, which is higher than that of MCCP-β. Mutational analysis reveals that the increased homodimeric interface area of TTCP-β contributes to its high thermal stability. Furthermore, 14 proline residues, which are mostly located in the TTCP-β loop regions, possibly contribute to the rigid loop structure compared with MCCP-β, which has only six proline residues. These findings, together with those from phylogenetic analysis, suggest that the structures of Thermus cytochromes c'-β, including TTCP-β, are optimized for function under the high-temperature conditions in which the source organisms live.
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Affiliation(s)
- Taisuke Yoshimi
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Sotaro Fujii
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, United Kingdom
| | - Hiroya Oki
- Research Institute for Microbial Diseases, Osaka University, Yamadaoka, Suita, Osaka, Japan
- Graduate School of Pharmaceutical Sciences, Osaka University, Yamadaoka, Suita, Osaka, Japan
| | - Takeshi Igawa
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
- Division of Bioresource Science, Amphibian Research Center, Hiroshima University, Higashi-Hiroshima, Japan
| | - Hannah R. Adams
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, United Kingdom
| | - Kengo Ueda
- Graduate School of Pharmaceutical Sciences, Osaka University, Yamadaoka, Suita, Osaka, Japan
| | - Kazuki Kawahara
- Graduate School of Pharmaceutical Sciences, Osaka University, Yamadaoka, Suita, Osaka, Japan
| | - Tadayasu Ohkubo
- Division of Bioresource Science, Amphibian Research Center, Hiroshima University, Higashi-Hiroshima, Japan
| | - Michael A. Hough
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, United Kingdom
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, United Kingdom
| | - Yoshihiro Sambongi
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
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Lalinská-Voleková B, Majerová H, Kautmanová I, Brachtýr O, Szabóová D, Arendt D, Brčeková J, Šottník P. Hydrous ferric oxides (HFO's) precipitated from contaminated waters at several abandoned Sb deposits - Interdisciplinary assessment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 821:153248. [PMID: 35051450 DOI: 10.1016/j.scitotenv.2022.153248] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 01/14/2022] [Accepted: 01/14/2022] [Indexed: 06/14/2023]
Abstract
The presented paper represents a comprehensive analysis of ochre sediments precipitated from Fe rich drainage waters contaminated by arsenic and antimony. Ochre samples from three abandoned Sb deposits were collected in three different seasons and were characterized from the mineralogical, geochemical, and microbiological point of view. They were formed mainly by poorly crystallized 2-line ferrihydrite, with the content of arsenic in samples ranging from 7 g·kg-1 to 130 g·kg-1 and content of antimony ranging from 0.25 g·kg-1 up to 12 g·kg-1. Next-generation sequencing approach with 16S RNA, 18S RNA and ITS markers was used to characterize bacterial, fungal, algal, metazoal and protozoal communities occurring in the HFOs. In the 16S RNA, the analysis dominated bacteria (96.2%) were mainly Proteobacteria (68.8%) and Bacteroidetes (10.2%) and to less extent also Acidobacteria, Actinobacteria, Cyanobacteria, Firmicutes, Nitrosprae and Chloroflexi. Alpha and beta diversity analysis revealed that the bacterial communities of individual sites do not differ significantly, and only subtle seasonal changes were observed. In this As and Sb rich, circumneutral microenvironment, rich in iron, sulfates and carbonates, methylotrophic bacteria (Methylobacter, Methylotenera), metal/reducing bacteria (Geobacter, Rhodoferax), metal-oxidizing and denitrifying bacteria (Gallionella, Azospira, Sphingopyxis, Leptothrix and Dechloromonas), sulfur-oxidizing bacteria (Sulfuricurvum, Desulphobulbaceae) and nitrifying bacteria (Nitrospira, Nitrosospira) accounted for the most dominant ecological groups and their impact over Fe, As, Sb, sulfur and nitrogen geocycles is discussed. This study provides evidence of diverse microbial communities that exist in drainage waters and are highly important in the process of mobilization or immobilization of the potentially toxic elements.
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Affiliation(s)
| | - Hana Majerová
- Hana Majerová, Cancer Research Institute, Department of Tumor Immunology, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 84505 Bratislava, Slovakia
| | - Ivona Kautmanová
- SNM-Natural History Museum, Vajanského náb. 2, P.O. BOX 13, 810 06 Bratislava, Slovakia
| | - Ondrej Brachtýr
- Comenius University in Bratislava, Faculty of Natural Sciences, Department of Mineralogy, Petrology and Economic Geology, Ilkovičova 6, 842 15 Bratislava, Slovakia
| | - Dana Szabóová
- SNM-Natural History Museum, Vajanského náb. 2, P.O. BOX 13, 810 06 Bratislava, Slovakia
| | - Darina Arendt
- SNM-Natural History Museum, Vajanského náb. 2, P.O. BOX 13, 810 06 Bratislava, Slovakia
| | - Jana Brčeková
- Comenius University in Bratislava, Faculty of Natural Sciences, Department of Mineralogy, Petrology and Economic Geology, Ilkovičova 6, 842 15 Bratislava, Slovakia
| | - Peter Šottník
- Comenius University in Bratislava, Faculty of Natural Sciences, Department of Mineralogy, Petrology and Economic Geology, Ilkovičova 6, 842 15 Bratislava, Slovakia
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Barkay T, Gu B. Demethylation─The Other Side of the Mercury Methylation Coin: A Critical Review. ACS ENVIRONMENTAL AU 2022; 2:77-97. [PMID: 37101582 PMCID: PMC10114901 DOI: 10.1021/acsenvironau.1c00022] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The public and environmental health consequences of mercury (Hg) methylation have drawn much attention and considerable research to Hg methylation processes and their dynamics in diverse environments and under a multitude of conditions. However, the net methylmercury (MeHg) concentration that accumulates in the environment is equally determined by the rate of MeHg degradation, a complex process mediated by a variety of biotic and abiotic mechanisms, about which our knowledge is limited. Here we review the current knowledge on MeHg degradation and its potential pathways and mechanisms. We describe detoxification by resistant microorganisms that employ the Hg resistance (mer) system to reductively break the carbon-mercury (C-Hg) bond producing methane (CH4) and inorganic mercuric Hg(II), which is then reduced by the mercuric reductase to elemental Hg(0). Very recent research has begun to elucidate a mechanism for the long-recognized mer-independent oxidative demethylation, likely involving some strains of anaerobic bacteria as well as aerobic methane-oxidizing bacteria, i.e., methanotrophs. In addition, photochemical and chemical demethylation processes are described, including the roles of dissolved organic matter (DOM) and free radicals as well as dark abiotic demethylation in the natural environment about which little is currently known. We focus on mechanisms and processes of demethylation and highlight the uncertainties and known effects of environmental factors leading to MeHg degradation. Finally, we suggest future research directions to further elucidate the chemical and biochemical mechanisms of biotic and abiotic demethylation and their significance in controlling net MeHg production in natural ecosystems.
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Affiliation(s)
- Tamar Barkay
- Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, New Jersey 08901, United States
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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Xu Z, Masuda Y, Wang X, Ushijima N, Shiratori Y, Senoo K, Itoh H. Genome-Based Taxonomic Rearrangement of the Order Geobacterales Including the Description of Geomonas azotofigens sp. nov. and Geomonas diazotrophica sp. nov. Front Microbiol 2021; 12:737531. [PMID: 34659166 PMCID: PMC8516083 DOI: 10.3389/fmicb.2021.737531] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 08/26/2021] [Indexed: 11/13/2022] Open
Abstract
Geobacterales is a recently proposed order comprising members who originally belonged to the well-known family Geobacteraceae, which is a key group in terrestrial ecosystems involved in biogeochemical cycles and has been widely investigated in bioelectrochemistry and bioenergy fields. Previous studies have illustrated the taxonomic structure of most members in this group based on genomic phylogeny; however, several members are still in a pendent or chaotic taxonomic status owing to the lack of genome sequences. To address this issue, we performed this taxonomic reassignment using currently available genome sequences, along with the description of two novel paddy soil-isolated strains, designated Red51T and Red69T, which are phylogenetically located within this order. Phylogenomic analysis based on 120 ubiquitous single-copy proteins robustly separated the species Geobacter luticola from other known genera and placed the genus Oryzomonas (fam. Geobacteraceae) into the family ‘Pseudopelobacteraceae’; thus, a novel genus Geomobilimonas is proposed, and the family ‘Pseudopelobacteraceae’ was emended. Moreover, genomic comparisons with similarity indexes, including average amino acid identity (AAI), percentage of conserved protein (POCP), and average nucleotide identity (ANI), showed proper thresholds as genera boundaries in this order with values of 70%, 65%, and 74% for AAI, POCP, and ANI, respectively. Based on this, the three species Geobacter argillaceus, Geobacter pelophilus, and Geobacter chapellei should be three novel genera, for which the names Geomobilibacter, Geoanaerobacter, and Pelotalea are proposed, respectively. In addition, the two novel isolated strains phylogenetically belonged to the genus Geomonas, family Geobacteraceae, and shared genomic similarity values higher than those of genera boundaries, but lower than those of species boundaries with each other and their neighbors. Taken together with phenotypic and chemotaxonomic characteristics similar to other Geomonas species, these two strains, Red51T and Red69T, represent two novel species in the genus Geomonas, for which the names Geomonas azotofigens sp. nov. and Geomonas diazotrophica sp. nov. are proposed, respectively.
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Affiliation(s)
- Zhenxing Xu
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Yoko Masuda
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Xueding Wang
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Natsumi Ushijima
- Support Section for Education and Research, Graduate School of Dental Medicine, Hokkaido University, Hokkaido, Japan
| | | | - Keishi Senoo
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
| | - Hideomi Itoh
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) Hokkaido, Hokkaido, Japan
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Nagahashi W, Yoshida N. Comparative evaluation of fibrous artificial carbons and bamboo charcoal in terms of recovery of current from sewage wastewater. J GEN APPL MICROBIOL 2021; 67:248-255. [PMID: 34470976 DOI: 10.2323/jgam.2021.05.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In this study, two fibrous carbon anodes (namely, pleated non-woven graphite (PNWG) and carbon brush (CB) made from artificial carbon) and bamboo charcoal (BC) were evaluated for current recovery from sewage wastewater. When these anodes were polarized at 0.2 V vs. Ag/AgCl in sewage wastewater, CB produced a maximum current of 2.9 A/m2. This exceeded that produced by PNWG (1.5 A/m2) and BC (1.4 A/m2). The accumulative charge recovery achieved with CB was superior to those achieved with the other two (1.6- and 2.2-fold higher than that with PNWG and BC, respectively). During the cyclic voltammetry analysis, CB demonstrated the highest catalytic current with maximum potential in the range of -0.6 to 0.4 V vs. Ag/AgCl and the smallest anode resistance (0.20 Ωm2). Direct cell counting revealed that the fibrous anodes (CB and PNWG) attached most of the cells in the anodes (80%), whereas BC did not. In contrast, the proportion of Geobacter species, a representative electrogenic microorganism in the total bacteria, was observed to be similar among the three anodes (4.4-5.8%). The tubular microbial fuel cell (ø 5.0 cm) equipped with an air-chamber core wrapped with an anion exchange membrane (AEM) and the CB delivered a current of 1.8 A/m2. This is higher than those reported in the existing literature for the same microbial fuel cell (MFC) configuration. This indicates that the alteration of the anode from planar to brush can contribute toward improving the current recovery through the air-cathode-AEM-MFC. The BC needs improvement to have more specific surface area, whereas it showed superiority in cost efficiency considering material and processing.
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Affiliation(s)
- Wataru Nagahashi
- Department of Civil and Environmental Engineering, Nagoya Institute of Technology (Nitech)
| | - Naoko Yoshida
- Department of Civil and Environmental Engineering, Nagoya Institute of Technology (Nitech)
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Xiao Y, Lin S, Hao T. Investigating the response of electrogenic metabolism to salinity in saline wastewater treatment for optimal energy output via microbial fuel cells. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 783:147092. [PMID: 34088164 DOI: 10.1016/j.scitotenv.2021.147092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 04/07/2021] [Accepted: 04/08/2021] [Indexed: 06/12/2023]
Abstract
In the current study, MFCs treating saline wastewater with the different conductivities of 5.0 ± 0.2, 7.7 ± 0.6, 10.5 ± 0.9, 13.0 ± 1.0, 15.3 ± 1.0, and 16.0 ± 0.1 mS/cm were investigated. Increasing salinity drives a considerable shift of microbial communities, and it also affects metabolic pathways in MFCs. Overwhelming acetate oxidizing electron transfer with moderate conductivities between 7.7 and 13.0 mS/cm led to high energy outputs. Power generation at the low conductivities of less than 7.7 mS/cm was restricted by the competition between fermentative bacteria (e.g., Lactobacillus) and exoelectrogens (e.g., Pseudomonas and Shewanella) for substrate utilization. Increasing salinity beyond 13 mS/cm suppressed the fermentation of glucose to butyrate. It also induced sulfidogenesis; sulfide oxidizing bacteria Desulfovibrio (5.2%), Desulfuromonas (3.7%) and exoelectrogen Pseudomonas (1.1%) formed a sulfur-driven current production, thereby resulting in low energy outputs. The present study revealed the effects of ionic conductivity on electrical energy production and provided insights into the dynamics of the MFCs substrate utilization.
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Affiliation(s)
- Yihang Xiao
- Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau
| | - Sen Lin
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Tianwei Hao
- Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau.
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11
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Mukherjee P, Pichiah S, Packirisamy G, Jang M. Biocatalyst physiology and interplay: a protagonist of MFC operation. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:43217-43233. [PMID: 34165738 DOI: 10.1007/s11356-021-15015-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 06/16/2021] [Indexed: 06/13/2023]
Abstract
Microbial fuel cells (MFC) have been foreseen as a sustainable renewable energy resource to meet future energy demand. In the past, several studies have been executed in both benchtop and pilot scale to produce electrical energy from wastewater. The key role players in this technology that leads to the operation are microbes, mainly bacteria. The dominant among them is termed as "exoelectrogens" that have the capability to produce and transport electron by utilizing waste source. The current review focuses on such electrogenic bacteria's involvement for enhanced power generation of MFC. The pathway of electron transfer in their cell along and its conduction to the extracellular environment of the MFC system are critically discussed. The interaction of the microbes in various MFC operational conditions, including the role of substrate and solid electron acceptors, i.e., anode, external resistance, temperature, and pH, was also discussed in depth along with biotechnological advancement and future research perspective.
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Affiliation(s)
- Priya Mukherjee
- Environmental Nanotechnology Laboratory, Department of Environmental Science and Engineering, Indian Institute of Technology (ISM), Dhanbad, Jharkhand, 826004, India
| | - Saravanan Pichiah
- Environmental Nanotechnology Laboratory, Department of Environmental Science and Engineering, Indian Institute of Technology (ISM), Dhanbad, Jharkhand, 826004, India.
| | - Gopinath Packirisamy
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India
| | - Min Jang
- Department of Environmental Engineering, Kwangwoon University, 447-1, Wolgye-dong Nowon-Gu, Seoul, South Korea
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12
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Zhang Z, Xu Z, Masuda Y, Wang X, Ushijima N, Shiratori Y, Senoo K, Itoh H. Geomesophilobacter sediminis gen. nov., sp. nov., Geomonas propionica sp. nov. and Geomonas anaerohicana sp. nov., three novel members in the family Geobacterecace isolated from river sediment and paddy soil. Syst Appl Microbiol 2021; 44:126233. [PMID: 34311149 DOI: 10.1016/j.syapm.2021.126233] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 07/06/2021] [Accepted: 07/09/2021] [Indexed: 11/29/2022]
Abstract
Bacteria in the family Geobacteraceae have been proven to fill important niches in a diversity of anaerobic environments and global biogeochemical processes. Here, three bacterial strains in this family, designated Red875T, Red259T, and Red421T were isolated from river sediment and paddy soils in Japan. All of them are Gram-staining-negative, strictly anaerobic, motile, flagellum-harboring cells that form red colonies on agar plates and are capable of utilizing Fe(III)-NTA, Fe(III) citrate, ferrihydrite, MnO2, fumarate, and nitrate as electron acceptors with acetate, propionate, pyruvate, and glucose as electron donors. Phylogenetic analysis based on the 16S rRNA gene and 92 concatenated core proteins sequences revealed that strains Red259T and Red421T clustered with the type strains of Geomonas species, whereas strain Red875T formed an independent lineage within the family Geobacteraceae. Genome comparison based on average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values clearly distinguished these three strains from other Geobacteraceae members, with lower values than the thresholds for species delineation. Moreover, strain Red875T also shared low average amino acid identity (AAI) and percentage of conserved proteins (POCP) values with the type species of the family Geobacteraceae. Based on these physiological, chemotaxonomic, and phylogenetic distinctions, we propose that strain Red875T (=NBRC 114290T = MCCC 1K04407T) represents a novel genus in the family Geobacteraceae, namely, Geomesophilobacter sediminis gen. nov., sp. nov., and strains Red259T (=NBRC 114288T = MCCC 1K05016T) and Red421T (=NBRC 114289T = MCCC 1K06216T) represent two novel independent species in the genus Geomonas, namely, Geomonas propionica sp. nov. and Geomonas anaerohicana sp. nov., respectively.
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Affiliation(s)
- Zhengcheng Zhang
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Zhenxing Xu
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
| | - Yoko Masuda
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
| | - Xueding Wang
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Natsumi Ushijima
- Support Section for Education and Research, Graduate School of Dental Medicine, Hokkaido University, Japan
| | | | - Keishi Senoo
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan; Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
| | - Hideomi Itoh
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Hokkaido, Japan
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13
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Functional Interrelationships of Microorganisms in Iron-Based Anaerobic Wastewater Treatment. Microorganisms 2021; 9:microorganisms9051039. [PMID: 34065964 PMCID: PMC8151836 DOI: 10.3390/microorganisms9051039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 05/07/2021] [Accepted: 05/10/2021] [Indexed: 11/16/2022] Open
Abstract
This study explicated the functional activities of microorganisms and their interrelationships under four previously reported iron reducing conditions to identify critical factors that governed the performance of these novel iron-dosed anaerobic biological wastewater treatment processes. Various iron-reducing bacteria (FeRB) and sulfate reducing bacteria (SRB) were identified as the predominant species that concurrently facilitated organics oxidation and the main contributors to removal of organics. The high organic contents of wastewater provided sufficient electron donors for active growth of both FeRB and SRB. In addition to the organic content, Fe (III) and sulfate concentrations (expressed by Fe/S ratio) were found to play a significant role in regulating the microbial abundance and functional activities. Various fermentative bacteria contributed to this FeRB-SRB synergy by fermenting larger organic compounds to smaller compounds, which were subsequently used by FeRB and SRB. Feammox (ferric reduction coupled to ammonium oxidation) bacterium was identified in the bioreactor fed with wastewater containing ammonium. Organic substrate level was a critical factor that regulated the competitive relationship between heterotrophic FeRB and Feammox bacteria. There were evidences that suggested a synergistic relationship between FeRB and nitrogen-fixing bacteria (NFB), where ferric iron and organics concentrations both promoted microbial activities of FeRB and NFB. A concept model was developed to illustrate the identified functional interrelationships and their governing factors for further development of the iron-based wastewater treatment systems.
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14
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Torres K, Álvarez-Hornos FJ, Gabaldón C, Marzal P. Start-Up of Chitosan-Assisted Anaerobic Sludge Bed Reactors Treating Light Oxygenated Solvents under Intermittent Operation. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18094986. [PMID: 34067161 PMCID: PMC8125441 DOI: 10.3390/ijerph18094986] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/04/2021] [Accepted: 05/05/2021] [Indexed: 01/20/2023]
Abstract
Quality of the granular sludge developed during the start-up of anaerobic up-flow sludge bed reactors is of crucial importance to ensure the process feasibility of treating industrial wastewater such as those containing solvents. In this study, the microbial granule formation from suspended-growth biomass was investigated in two chitosan-assisted reactors. These reactors operated mimicking industrial sites working with night closures treating a mixture of ethanol, ethyl acetate, and 1-ethoxy-2-propanol. Each reactor operated under different hydrodynamic regimes typical from UASB (R1: <0.15 m h−1) and EGSB (R2: 3 m h−1). High soluble COD removal efficiencies (>90%) accompanied by rapid formation of robust anaerobic granules were achieved at both up-flow velocity levels. After three weeks from the start-up, mean size diameters of 475 µm and 354 µm were achieved for R1 and R2, respectively. The performance of the process was found to be stable for the whole operational period of 106 days treating intermittent OLR up to 13 kg COD m−3 d−1. A memory dose of chitosan at day 42 was beneficial to guarantee good quality of the granules by offsetting the negative impact of intermittent water supply on the granular size. Methanocorpusculum was identified as the dominant archaea at both up-flow velocities. Acetobacterium, Geobacter and Desulfovibrio bacteria were also abundant, demonstrating its role on the degradation of light-oxygenated solvents.
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15
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Pérez-Rodríguez I, Choi JK, Abuyen K, Tyler M, Ronkowski C, Romero E, Trujillo A, Tremblay J, Viney I, Savalia P, Amend JP. Geothermobacter hydrogeniphilus sp. nov., a mesophilic, iron(III)-reducing bacterium from seafloor/subseafloor environments in the Pacific Ocean, and emended description of the genus Geothermobacter. Int J Syst Evol Microbiol 2021; 71. [PMID: 33877046 DOI: 10.1099/ijsem.0.004739] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A novel mesophilic, anaerobic, mixotrophic bacterium, with designated strains EPR-MT and HR-1, was isolated from a semi-extinct hydrothermal vent at the East Pacific Rise and from an Fe-mat at Lō'ihi Seamount, respectively. The cells were Gram-negative, pleomorphic rods of about 2.0 µm in length and 0.5 µm in width. Strain EPR-MT grew between 25 and 45 °C (optimum, 37.5-40 °C), 10 and 50 g l-1 NaCl (optimum, 15-20 g l-1) and pH 5.5 and 8.6 (optimum, pH 6.4). Strain HR-1 grew between 20 and 45 °C (optimum, 37.5-40 °C), 10 and 50 g l-1 NaCl (optimum, 15-25 g l-1) and pH 5.5 and 8.6 (optimum, pH 6.4). Shortest generation times with H2 as the primary electron donor, CO2 as the carbon source and ferric citrate as terminal electron acceptor were 6.7 and 5.5 h for EPR-MT and HR-1, respectively. Fe(OH)3, MnO2, AsO4 3-, SO4 2-, SeO4 2-, S2O3 2-, S0 and NO3 - were also used as terminal electron acceptors. Acetate, yeast extract, formate, lactate, tryptone and Casamino acids also served as both electron donors and carbon sources. G+C content of the genomic DNA was 59.4 mol% for strain EPR-MT and 59.2 mol% for strain HR-1. Phylogenetic and phylogenomic analyses indicated that both strains were closely related to each other and to Geothermobacter ehrlichii, within the class δ-Proteobacteria (now within the class Desulfuromonadia). Based on phylogenetic and phylogenomic analyses in addition to physiological and biochemical characteristics, both strains were found to represent a novel species within the genus Geothermobacter, for which the name Geothermobacter hydrogeniphilus sp. nov. is proposed. Geothermobacter hydrogeniphilus is represented by type strain EPR-MT (=JCM 32109T=KCTC 15831T=ATCC TSD-173T) and strain HR-1 (=JCM 32110=KCTC 15832).
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Affiliation(s)
- Ileana Pérez-Rodríguez
- Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA.,Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089, USA.,Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jessica K Choi
- Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Karla Abuyen
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA.,Community College Cultivation Cohort, University of Southern California, Los Angeles, CA 90089, USA.,Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Madeline Tyler
- Present address: College of Pharmacy, Oregon State University, Corvallis, OR 97330, USA.,Community College Cultivation Cohort, University of Southern California, Los Angeles, CA 90089, USA
| | - Cynthia Ronkowski
- Community College Cultivation Cohort, University of Southern California, Los Angeles, CA 90089, USA
| | - Eric Romero
- Present address: Department of Nuclear Engineering, University of California, Berkeley, CA 94720, USA.,Community College Cultivation Cohort, University of Southern California, Los Angeles, CA 90089, USA
| | - Anthony Trujillo
- Community College Cultivation Cohort, University of Southern California, Los Angeles, CA 90089, USA
| | - Jason Tremblay
- Community College Cultivation Cohort, University of Southern California, Los Angeles, CA 90089, USA
| | - Isabella Viney
- Present address: Department of Microbiology, University of Arizona, Tucson, AZ 85721, USA.,Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Pratixaben Savalia
- Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Jan P Amend
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA.,Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089, USA
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16
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Itoh H, Xu Z, Masuda Y, Ushijima N, Hayakawa C, Shiratori Y, Senoo K. Geomonas silvestris sp. nov., Geomonas paludis sp. nov. and Geomonas limicola sp. nov., isolated from terrestrial environments, and emended description of the genus Geomonas. Int J Syst Evol Microbiol 2020; 71. [PMID: 33295856 DOI: 10.1099/ijsem.0.004607] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Three bacterial strains, designated Red330T, Red736T and Red745T, were isolated from forest and paddy soils in Japan. Strains Red330T, Red736T and Red745T are flagella-harbouring and strictly anaerobic bacteria forming red colonies. A 16S rRNA gene sequence-based phylogenetic tree showed that all three strains were located in a cluster, including the type strains of Geomonas species, which were recently separated from the genus Geobacter within the family Geobacteraceae. Similarities of the 16S rRNA gene sequences among the three strains and Geomonas oryzae S43T, the type species of the genus Geomonas, were 96.3-98.5 %. The genome-related indexes, average nucleotide identity, digital DNA-DNA hybridization, and average amino acid identity, among the three strains and G. oryzae S43T were 74.7-86.8 %, 21.2-33.3 % and 70.4-89.8 %, respectively, which were lower than the species delineation thresholds. Regarding the phylogenetic relationships based on genome sequences, the three strains clustered with the type strains of Geomonas species, which were independent from the type strains of Geobacter species. The distinguishableness of the three isolated strains was supported by physiological and chemotaxonomic properties, with the profile of availability of electron donors and cellular fatty acids composition being particularly different among them. Based on genetic, phylogenetic and phenotypic properties, the three isolates represent three novel independent species in the genus Geomonas, for which the names Geomonas silvestris sp. nov., Geomonas paludis sp. nov. and Geomonas limicola sp. nov. are proposed. The type strains are Red330T (=NBRC 114028T=MCCC 1K03949T), Red736T (=NBRC 114029T=MCCC 1K03950T) and Red745T (=NBRC 114030T=MCCC 1K03951T), respectively.
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Affiliation(s)
- Hideomi Itoh
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukisamu-Higashi, Toyohira-ku, Sapporo 062-8517, Japan
| | - Zhenxing Xu
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yoko Masuda
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Natsumi Ushijima
- Support Section for Education and Research, Graduate School of Dental Medicine, Hokkaido University, Hokkaido 060-8586, Japan
| | - Chie Hayakawa
- School of Agriculture, Utsunomiya University, Tochigi 321-8505, Japan
| | - Yutaka Shiratori
- Niigata Agricultural Research Institute, Niigata 940-0826, Japan
| | - Keishi Senoo
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo 113-8657, Japan.,Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
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17
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Waite DW, Chuvochina M, Pelikan C, Parks DH, Yilmaz P, Wagner M, Loy A, Naganuma T, Nakai R, Whitman WB, Hahn MW, Kuever J, Hugenholtz P. Proposal to reclassify the proteobacterial classes Deltaproteobacteria and Oligoflexia, and the phylum Thermodesulfobacteria into four phyla reflecting major functional capabilities. Int J Syst Evol Microbiol 2020; 70:5972-6016. [DOI: 10.1099/ijsem.0.004213] [Citation(s) in RCA: 696] [Impact Index Per Article: 139.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The class
Deltaproteobacteria
comprises an ecologically and metabolically diverse group of bacteria best known for dissimilatory sulphate reduction and predatory behaviour. Although this lineage is the fourth described class of the phylum
Proteobacteria
, it rarely affiliates with other proteobacterial classes and is frequently not recovered as a monophyletic unit in phylogenetic analyses. Indeed, one branch of the class
Deltaproteobacteria
encompassing Bdellovibrio-like predators was recently reclassified into a separate proteobacterial class, the
Oligoflexia
. Here we systematically explore the phylogeny of taxa currently assigned to these classes using 120 conserved single-copy marker genes as well as rRNA genes. The overwhelming majority of markers reject the inclusion of the classes
Deltaproteobacteria
and
Oligoflexia
in the phylum
Proteobacteria
. Instead, the great majority of currently recognized members of the class
Deltaproteobacteria
are better classified into four novel phylum-level lineages. We propose the names Desulfobacterota phyl. nov. and Myxococcota phyl. nov. for two of these phyla, based on the oldest validly published names in each lineage, and retain the placeholder name SAR324 for the third phylum pending formal description of type material. Members of the class
Oligoflexia
represent a separate phylum for which we propose the name Bdellovibrionota phyl. nov. based on priority in the literature and general recognition of the genus Bdellovibrio. Desulfobacterota phyl. nov. includes the taxa previously classified in the phylum
Thermodesulfobacteria
, and these reclassifications imply that the ability of sulphate reduction was vertically inherited in the
Thermodesulfobacteria
rather than laterally acquired as previously inferred. Our analysis also indicates the independent acquisition of predatory behaviour in the phyla Myxococcota and Bdellovibrionota, which is consistent with their distinct modes of action. This work represents a stable reclassification of one of the most taxonomically challenging areas of the bacterial tree and provides a robust framework for future ecological and systematic studies.
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Affiliation(s)
- David W Waite
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, Australia
| | - Maria Chuvochina
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, Australia
| | - Claus Pelikan
- University of Vienna, Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria
| | - Donovan H Parks
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, Australia
| | | | - Michael Wagner
- University of Vienna, Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria
| | - Alexander Loy
- University of Vienna, Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria
| | | | - Ryosuke Nakai
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Sapporo, Hokkaido, Japan
| | - William B Whitman
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Martin W Hahn
- Research Department for Limnology, University of Innsbruck, Mondsee, Austria
| | - Jan Kuever
- Department of Microbiology, Bremen Institute for Materials Testing, Bremen, Germany
| | - Philip Hugenholtz
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, Australia
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18
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Li T, Zhou Q. The key role of Geobacter in regulating emissions and biogeochemical cycling of soil-derived greenhouse gases. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 266:115135. [PMID: 32650301 DOI: 10.1016/j.envpol.2020.115135] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/11/2020] [Accepted: 06/26/2020] [Indexed: 06/11/2023]
Abstract
In the past two decades, more and more attentions have been paid to soil-derived greenhouse gases (GHGs) including carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) because there are signs that they have rising negative impacts on the sustainability of the earth surface system. Farmlands, particularly paddy soils, have been regarded as the most important emitter of GHGs (nearly 17%) due to a large influx of fertilization and the abundance in animals, plants and microorganisms. Geobacter, as an electroactive microorganism widely occurred in soil, has been well studied on electron transport mechanisms and the direct interspecies electron transfer. These studies on Geobacter illustrate that it has the ability to be involved in the pathways of soil GHG emissions through redox reactions under anaerobic conditions. In this review, production mechanisms of soil-derived GHGs and the amount of these GHGs produced had been first summarized. The cycling process of CH4 and N2O was described from the view of microorganisms and discussed the co-culture relationships between Geobacter and other microorganisms. Furthermore, the role of Geobacter in the production of soil-derived GHGs is defined by biogeochemical cycling. The complete view on the effect of Geobacter on the emission of soil-derived GHGs has been shed light on, and appeals further investigation.
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Affiliation(s)
- Tian Li
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China
| | - Qixing Zhou
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China.
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19
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Cavaleiro AJ, Guedes AP, Silva SA, Arantes AL, Sequeira JC, Salvador AF, Sousa DZ, Stams AJM, Alves MM. Effect of Sub-Stoichiometric Fe(III) Amounts on LCFA Degradation by Methanogenic Communities. Microorganisms 2020; 8:microorganisms8091375. [PMID: 32906848 PMCID: PMC7564256 DOI: 10.3390/microorganisms8091375] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/01/2020] [Accepted: 09/04/2020] [Indexed: 02/06/2023] Open
Abstract
Long-chain fatty acids (LCFA) are common contaminants in municipal and industrial wastewater that can be converted anaerobically to methane. A low hydrogen partial pressure is required for LCFA degradation by anaerobic bacteria, requiring the establishment of syntrophic relationships with hydrogenotrophic methanogens. However, high LCFA loads can inhibit methanogens, hindering biodegradation. Because it has been suggested that anaerobic degradation of these compounds may be enhanced by the presence of alternative electron acceptors, such as iron, we investigated the effect of sub-stoichiometric amounts of Fe(III) on oleate (C18:1 LCFA) degradation by suspended and granular methanogenic sludge. Fe(III) accelerated oleate biodegradation and hydrogenotrophic methanogenesis in the assays with suspended sludge, with H2-consuming methanogens coexisting with iron-reducing bacteria. On the other hand, acetoclastic methanogenesis was delayed by Fe(III). These effects were less evident with granular sludge, possibly due to its higher initial methanogenic activity relative to suspended sludge. Enrichments with close-to-stoichiometric amounts of Fe(III) resulted in a microbial community mainly composed of Geobacter, Syntrophomonas, and Methanobacterium genera, with relative abundances of 83-89%, 3-6%, and 0.2-10%, respectively. In these enrichments, oleate was biodegraded to acetate and coupled to iron-reduction and methane production, revealing novel microbial interactions between syntrophic LCFA-degrading bacteria, iron-reducing bacteria, and methanogens.
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Affiliation(s)
- Ana J. Cavaleiro
- Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; (A.P.G.); (S.A.S.); (A.L.A.); (J.C.S.); (A.F.S.); (D.Z.S.); (A.J.M.S.); (M.M.A.)
- Correspondence: ; Tel.: +35-1253604423
| | - Ana P. Guedes
- Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; (A.P.G.); (S.A.S.); (A.L.A.); (J.C.S.); (A.F.S.); (D.Z.S.); (A.J.M.S.); (M.M.A.)
| | - Sérgio A. Silva
- Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; (A.P.G.); (S.A.S.); (A.L.A.); (J.C.S.); (A.F.S.); (D.Z.S.); (A.J.M.S.); (M.M.A.)
| | - Ana L. Arantes
- Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; (A.P.G.); (S.A.S.); (A.L.A.); (J.C.S.); (A.F.S.); (D.Z.S.); (A.J.M.S.); (M.M.A.)
| | - João C. Sequeira
- Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; (A.P.G.); (S.A.S.); (A.L.A.); (J.C.S.); (A.F.S.); (D.Z.S.); (A.J.M.S.); (M.M.A.)
| | - Andreia F. Salvador
- Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; (A.P.G.); (S.A.S.); (A.L.A.); (J.C.S.); (A.F.S.); (D.Z.S.); (A.J.M.S.); (M.M.A.)
| | - Diana Z. Sousa
- Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; (A.P.G.); (S.A.S.); (A.L.A.); (J.C.S.); (A.F.S.); (D.Z.S.); (A.J.M.S.); (M.M.A.)
- Laboratory of Microbiology, Wageningen University & Research, 6708 WE Wageningen, The Netherlands
| | - Alfons J. M. Stams
- Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; (A.P.G.); (S.A.S.); (A.L.A.); (J.C.S.); (A.F.S.); (D.Z.S.); (A.J.M.S.); (M.M.A.)
- Laboratory of Microbiology, Wageningen University & Research, 6708 WE Wageningen, The Netherlands
| | - M. Madalena Alves
- Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; (A.P.G.); (S.A.S.); (A.L.A.); (J.C.S.); (A.F.S.); (D.Z.S.); (A.J.M.S.); (M.M.A.)
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Diazotrophic Anaeromyxobacter Isolates from Soils. Appl Environ Microbiol 2020; 86:AEM.00956-20. [PMID: 32532868 DOI: 10.1128/aem.00956-20] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 06/04/2020] [Indexed: 11/20/2022] Open
Abstract
Biological nitrogen fixation is an essential reaction in a major pathway for supplying nitrogen to terrestrial environments. Previous culture-independent analyses based on soil DNA/RNA/protein sequencing could globally detect the nitrogenase genes/proteins of Anaeromyxobacter (in the class Deltaproteobacteria), commonly distributed in soil environments and predominant in paddy soils; this suggests the importance of Anaeromyxobacter in nitrogen fixation in soil environments. However, direct experimental evidence is lacking; there has been no research on the genetic background and ability of Anaeromyxobacter to fix nitrogen. Therefore, we verified the diazotrophy of Anaeromyxobacter based on both genomic and culture-dependent analyses using Anaeromyxobacter sp. strains PSR-1 and Red267 isolated from soils. Based on the comparison of nif gene clusters, strains PSR-1 and Red267 as well as strains Fw109-5, K, and diazotrophic Geobacter and Pelobacter in the class Deltaproteobacteria contain the minimum set of genes for nitrogenase (nifBHDKEN). These results imply that Anaeromyxobacter species have the ability to fix nitrogen. In fact, Anaeromyxobacter PSR-1 and Red267 exhibited N2-dependent growth and acetylene reduction activity (ARA) in vitro Transcriptional activity of the nif gene was also detected when both strains were cultured with N2 gas as a sole nitrogen source, indicating that Anaeromyxobacter can fix and assimilate N2 gas by nitrogenase. In addition, PSR-1- or Red267-inoculated soil showed ARA activity and the growth of the inoculated strains on the basis of RNA-based analysis, demonstrating that Anaeromyxobacter can fix nitrogen in the paddy soil environment. Our study provides novel insights into the pivotal environmental function, i.e., nitrogen fixation, of Anaeromyxobacter, which is a common soil bacterium.IMPORTANCE Anaeromyxobacter is globally distributed in soil environments, especially predominant in paddy soils. Current studies based on environmental DNA/RNA analyses frequently detect gene fragments encoding nitrogenase of Anaeromyxobacter from various soil environments. Although the importance of Anaeromyxobacter as a diazotroph in nature has been suggested by culture-independent studies, there has been no solid evidence and validation from genomic and culture-based analyses that Anaeromyxobacter fixes nitrogen. This study demonstrates that Anaeromyxobacter harboring nitrogenase genes exhibits diazotrophic ability; moreover, N2-dependent growth was demonstrated in vitro and in the soil environment. Our findings indicate that nitrogen fixation is important for Anaeromyxobacter to survive under nitrogen-deficient environments and provide a novel insight into the environmental function of Anaeromyxobacter, which is a common bacterium in soils.
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Description of Three Novel Members in the Family Geobacteraceae, Oryzomonas japonicum gen. nov., sp. nov., Oryzomonas sagensis sp. nov., and Oryzomonas ruber sp. nov. Microorganisms 2020; 8:microorganisms8050634. [PMID: 32349406 PMCID: PMC7285026 DOI: 10.3390/microorganisms8050634] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 04/24/2020] [Accepted: 04/25/2020] [Indexed: 02/07/2023] Open
Abstract
Bacteria of the family Geobacteraceae are particularly common and deeply involved in many biogeochemical processes in terrestrial and freshwater environments. As part of a study to understand biogeochemical cycling in freshwater sediments, three iron-reducing isolates, designated as Red96T, Red100T, and Red88T, were isolated from the soils of two paddy fields and pond sediment located in Japan. The cells were Gram-negative, strictly anaerobic, rod-shaped, motile, and red-pigmented on agar plates. Growth of these three strains was coupled to the reduction of Fe(III)-NTA, Fe(III) citrate, and ferrihydrite with malate, methanol, pyruvate, and various organic acids and sugars serving as alternate electron donors. Phylogenetic analysis based on the housekeeping genes (16S rRNA gene, gyrB, rpoB, nifD, fusA, and recA) and 92 concatenated core genes indicated that all the isolates constituted a coherent cluster within the family Geobacteraceae. Genomic analyses, including average nucleotide identity and DNA–DNA hybridization, clearly differentiated the strains Red96T, Red100T, and Red88T from other species in the family Geobacteraceae, with values below the thresholds for species delineation. Along with the genomic comparison, the chemotaxonomic features further helped distinguish the three isolates from each other. In addition, the lower values of average amino acid identity and percentage of conserved protein, as well as biochemical differences with their relatives, indicated that the three strains represented a novel genus in the family Geobacteraceae. Hence, we concluded that strains Red96T, Red100T, and Red88T represented three novel species of a novel genus in the family Geobacteraceae, for which the names Oryzomonas japonicum gen. nov., sp. nov., Oryzomonas sagensis sp. nov., and Oryzomonas ruber sp. nov. are proposed, with type strains Red96T (= NBRC 114286T = MCCC 1K04376T), Red100T (= NBRC 114287T = MCCC 1K04377T), and Red88T (= MCCC 1K03694T = JCM 33033T), respectively.
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Fukuyama Y, Inoue M, Omae K, Yoshida T, Sako Y. Anaerobic and hydrogenogenic carbon monoxide-oxidizing prokaryotes: Versatile microbial conversion of a toxic gas into an available energy. ADVANCES IN APPLIED MICROBIOLOGY 2020; 110:99-148. [PMID: 32386607 DOI: 10.1016/bs.aambs.2019.12.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Carbon monoxide (CO) is a gas that is toxic to various organisms including humans and even microbes; however, it has low redox potential, which can fuel certain microbes, namely, CO oxidizers. Hydrogenogenic CO oxidizers utilize an energy conservation system via a CO dehydrogenase/energy-converting hydrogenase complex to produce hydrogen gas, a zero emission fuel, by CO oxidation coupled with proton reduction. Biochemical and molecular biological studies using a few model organisms have revealed their enzymatic reactions and transcriptional response mechanisms using CO. Biotechnological studies for CO-dependent hydrogen production have also been carried out with these model organisms. In this chapter, we review recent advances in the studies of these microbes, which reveal their unique and versatile metabolic profiles and provides future perspectives on ecological roles and biotechnological applications. Over the past decade, the number of isolates has doubled (37 isolates in 5 phyla, 20 genera, and 32 species). Some of the recently isolated ones show broad specificity to electron acceptors. Moreover, accumulating genomic information predicts their unique physiologies and reveals their phylogenomic relationships with novel potential hydrogenogenic CO oxidizers. Combined with genomic database surveys, a molecular ecological study has unveiled the wide distribution and low abundance of these microbes. Finally, recent biotechnological applications of hydrogenogenic CO oxidizers have been achieved via diverse approaches (e.g., metabolic engineering and co-cultivation), and the identification of thermophilic facultative anaerobic CO oxidizers will promote industrial applications as oxygen-tolerant biocatalysts for efficient hydrogen production by genomic engineering.
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Affiliation(s)
- Yuto Fukuyama
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Masao Inoue
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Kimiho Omae
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Takashi Yoshida
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Yoshihiko Sako
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan.
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Yuan K, Chen X, Chen P, Huang Y, Jiang J, Luan T, Chen B, Wang X. Mercury methylation-related microbes and genes in the sediments of the Pearl River Estuary and the South China Sea. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 185:109722. [PMID: 31577991 DOI: 10.1016/j.ecoenv.2019.109722] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 09/14/2019] [Accepted: 09/23/2019] [Indexed: 05/16/2023]
Abstract
Methylmercury (MeHg) is a toxicant that mainly originates from in situ microbial methylation of inorganic mercury (Hg) in the environment and poses a severe health risk to the public. However, the characteristics of the Hg-methylating microbial community and its relationship with MeHg production in various environments remain to be understood. In the present study, Hg-methylating microbial communities and genes (hgcAB cluster) in the sediments of the Pearl River (PR), Pearl River Estuary (PRE) and South China Sea (SCS) were investigated at a large spatial scale using high-throughput sequencing-based approaches. The results showed that sulfur-reducing bacteria (SRB) and iron-reducing bacteria (IRB) were consistently the dominant microbial strains responsible for the methylation of inorganic Hg in all three regions investigated. The abundance and diversity of Hg-methylating communities and genes were both found to be higher in the PR sediments compared to that in the PRE and SCS sediments, and in good agreement with the spatial distribution of MeHg. Furthermore, a significant correlation was observed between the MeHg concentration and the abundance of both hgcA and hgcB genes in the sediments of the PR, PRE and SCS regions. Overall, the present study suggested that there was the presence of a close link between MeHg and Hg-methylating communities or genes in the ambient aquatic environment, which could be used to reflect the potential of in situ MeHg production.
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Affiliation(s)
- Ke Yuan
- Southern Marine Science and Engineering Guangdong Laboratory, School of Marine Sciences, Sun Yat-Sen University, Zhuhai, 519082, China
| | - Xin Chen
- Southern Marine Science and Engineering Guangdong Laboratory, School of Marine Sciences, Sun Yat-Sen University, Zhuhai, 519082, China
| | - Ping Chen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China
| | - Yongshun Huang
- Guangdong Provincial Hospital for Occupational Diseases Prevention and Treatment, Guangzhou, 510300, China
| | - Jie Jiang
- Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
| | - Tiangang Luan
- Southern Marine Science and Engineering Guangdong Laboratory, School of Marine Sciences, Sun Yat-Sen University, Zhuhai, 519082, China; State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China
| | - Baowei Chen
- Southern Marine Science and Engineering Guangdong Laboratory, School of Marine Sciences, Sun Yat-Sen University, Zhuhai, 519082, China.
| | - Xiaowei Wang
- Southern Marine Science and Engineering Guangdong Laboratory, School of Marine Sciences, Sun Yat-Sen University, Zhuhai, 519082, China.
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Xu Z, Masuda Y, Itoh H, Ushijima N, Shiratori Y, Senoo K. Geomonas oryzae gen. nov., sp. nov., Geomonas edaphica sp. nov., Geomonas ferrireducens sp. nov., Geomonas terrae sp. nov., Four Ferric-Reducing Bacteria Isolated From Paddy Soil, and Reclassification of Three Species of the Genus Geobacter as Members of the Genus Geomonas gen. nov. Front Microbiol 2019; 10:2201. [PMID: 31608033 PMCID: PMC6773877 DOI: 10.3389/fmicb.2019.02201] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Accepted: 09/09/2019] [Indexed: 11/13/2022] Open
Abstract
In paddy soil, bacteria from the family Geobacteraceae have been shown to strongly contribute to the biogeochemical cycle. However, no Geobacteraceae species with validly published names have been isolated from paddy soil. In this study, we isolated and characterized four novel ferric reducing bacteria in the family Geobacteraceae from the paddy soils of three different fields in Japan. The four strains, S43T, Red53T, S62T, and Red111T, were Gram-stain negative, strictly anaerobic, chemoheterotrophic, and motile with peritrichous flagella. Phylogenetic studies based on 16S rRNA gene sequences, five concatenated housekeeping genes (fusA, rpoB, recA, nifD, and gyrB) and 92 concatenated core genes revealed that the four strains belong to the family Geobacteraceae and are most closely related to Geobacter bemidjiensis BemT (97.4-98.2%, 16S rRNA gene sequence similarities) and Geobacter bremensis Dfr1T (97.1-98.0%). Genomic analysis with average nucleotide identity (ANI) and digital DNA-DNA hybridization (GGDC) calculations clearly distinguished the four isolated strains from other species of the family Geobacteraceae and indicated that strains S43T, Red53T, S62T, and Red111T represent independent species, with values below the thresholds for species delineation. Chemotaxonomic characteristics, including major fatty acid and whole cell protein profiles, showed differences among the isolates and their closest relatives, which were consistent with the results of DNA fingerprints and physiological characterization. Additionally, each of the four isolates shared a low 16S rRNA gene sequence similarity (92.4%) and average amino acid identity (AAI) with the type strain of the type species Geobacter metallireducens. Overall, strains S43T, Red53T, S62T, and Red111T represent four novel species, which we propose to classify in a novel genus of the family Geobacteraceae, and the names Geomonas oryzae gen. nov., sp. nov. (type strain S43T), Geomonas edaphica sp. nov. (type strain Red53T), Geomonas ferrireducens sp. nov. (type strain S62T), and Geomonas terrae sp. nov. (type strain Red111T) are proposed. Based on phylogenetic and genomic analyses, we also propose the reclassification of Geobacter bremensis as Geomonas bremensis comb. nov., Geobacter pelophilus as Geomonas pelophila comb. nov., and Geobacter bemidjiensis as Geomonas bemidjiensis comb. nov.
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Affiliation(s)
- Zhenxing Xu
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Yoko Masuda
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Hideomi Itoh
- Bioproduction Research Institute, National Institute of Advanced Industrial Sciences and Technology, Hokkaido, Japan
| | - Natsumi Ushijima
- Support Section for Education and Research, Graduate School of Dental Medicine, Hokkaido University, Hokkaido, Japan
| | | | - Keishi Senoo
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
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Sun D, Wan X, Liu W, Xia X, Huang F, Wang A, Smith JA, Dang Y, Holmes DE. Characterization of the genome from Geobacter anodireducens, a strain with enhanced current production in bioelectrochemical systems. RSC Adv 2019; 9:25890-25899. [PMID: 35530078 PMCID: PMC9070056 DOI: 10.1039/c9ra02343g] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 07/20/2019] [Indexed: 11/21/2022] Open
Abstract
Geobacter anodireducens is unique in that it can generate high current densities in bioelectrochemical systems (BES) operating under high salt conditions. This ability is important for the development of BES treating high salt wastewater and microbial desalination cells. Therefore, the genome of G. anodireducens was characterized to identify proteins that might allow this strain to survive in high salt BES. Comparison to other Geobacter species revealed that 81 of its 87 c-type cytochromes had homologs in G. soli and G. sulfurreducens. Genes coding for many extracellular electron transfer proteins were also detected, including the outer membrane c-type cytochromes OmcS and OmcZ and the soluble c-type cytochrome PgcA. G. anodireducens also appears to have numerous membrane complexes involved in the translocation of protons and sodium ions and channels that provide protection against osmotic shock. In addition, it has more DNA repair genes than most Geobacter species, suggesting that it might be able to more rapidly repair DNA damage caused in high salt and low pH anode environments. Although this genomic analysis provides invaluable insight into mechanisms used by G. anodireducens to survive in high salt BES, genetic, transcriptomic, and proteomic studies will need to be done to validate their roles.
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Affiliation(s)
- Dan Sun
- Ocean College, Zhejiang University Zhoushan 316021 P. R. China
| | - Xinyuan Wan
- Ocean College, Zhejiang University Zhoushan 316021 P. R. China
| | - Wenzong Liu
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, China Academy of Sciences Beijing 100084 P. R. China
| | - Xue Xia
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, China Academy of Sciences Beijing 100084 P. R. China
| | - Fangliang Huang
- College of Life Sciences, Zhejiang University Hangzhou 310058 P. R. China
| | - Aijie Wang
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, China Academy of Sciences Beijing 100084 P. R. China
| | - Jessica A Smith
- Department of Biomolecular Sciences, Central Connecticut State University 1615 Stanley Street New Britain CT 06050 USA
| | - Yan Dang
- Beijing Key Laboratory for Source Control Technology of Water Pollution, Engineering Research Center for Water Pollution Source Control and Eco-remediation, College of Environmental Science & Engineering, Beijing Forestry University 35 Tsinghua East Road Beijing 100083 China
| | - Dawn E Holmes
- Department of Physical and Biological Sciences, Western New England University 1215 Wilbraham Rd Springfield MA 01190 USA
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Zakharyuk AG, Ryzhmanova YV, Avtukh AN, Shcherbakova VA. Iron-Reducing Microbial Communities of the Lake Baikal Low-Temperature Bottom Sediments. Microbiology (Reading) 2019. [DOI: 10.1134/s0026261719020139] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Abstract
The family Geobacteraceae, with its only valid genus Geobacter, comprises deltaproteobacteria ubiquitous in soil, sediments, and subsurface environments where metal reduction is an active process. Research for almost three decades has provided novel insights into environmental processes and biogeochemical reactions not previously known to be carried out by microorganisms. At the heart of the environmental roles played by Geobacter bacteria is their ability to integrate redox pathways and regulatory checkpoints that maximize growth efficiency with electron donors derived from the decomposition of organic matter while respiring metal oxides, particularly the often abundant oxides of ferric iron. This metabolic specialization is complemented by versatile metabolic reactions, respiratory chains, and sensory networks that allow specific members to adaptively respond to environmental cues to integrate organic and inorganic contaminants in their oxidative and reductive metabolism, respectively. Thus, Geobacteraceae are important members of the microbial communities that degrade hydrocarbon contaminants under iron-reducing conditions and that contribute, directly or indirectly, to the reduction of radionuclides, toxic metals, and oxidized species of nitrogen. Their ability to produce conductive pili as nanowires for discharging respiratory electrons to solid-phase electron acceptors and radionuclides, or for wiring cells in current-harvesting biofilms highlights the unique physiological traits that make these organisms attractive biological platforms for bioremediation, bioenergy, and bioelectronics application. Here we review some of the most notable physiological features described in Geobacter species since the first model representatives were recovered in pure culture. We provide a historical account of the environmental research that has set the foundation for numerous physiological studies and the laboratory tools that had provided novel insights into the role of Geobacter in the functioning of microbial communities from pristine and contaminated environments. We pay particular attention to latest research, both basic and applied, that has served to expand the field into new directions and to advance interdisciplinary knowledge. The electrifying physiology of Geobacter, it seems, is alive and well 30 years on.
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Omae K, Fukuyama Y, Yasuda H, Mise K, Yoshida T, Sako Y. Diversity and distribution of thermophilic hydrogenogenic carboxydotrophs revealed by microbial community analysis in sediments from multiple hydrothermal environments in Japan. Arch Microbiol 2019; 201:969-982. [PMID: 31030239 PMCID: PMC6687684 DOI: 10.1007/s00203-019-01661-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 03/15/2019] [Accepted: 04/15/2019] [Indexed: 12/18/2022]
Abstract
In hydrothermal environments, carbon monoxide (CO) utilisation by thermophilic hydrogenogenic carboxydotrophs may play an important role in microbial ecology by reducing toxic levels of CO and providing H2 for fuelling microbial communities. We evaluated thermophilic hydrogenogenic carboxydotrophs by microbial community analysis. First, we analysed the correlation between carbon monoxide dehydrogenase (CODH)–energy-converting hydrogenase (ECH) gene cluster and taxonomic affiliation by surveying an increasing genomic database. We identified 71 genome-encoded CODH–ECH gene clusters, including 46 whose owners were not reported as hydrogenogenic carboxydotrophs. We identified 13 phylotypes showing > 98.7% identity with these taxa as potential hydrogenogenic carboxydotrophs in hot springs. Of these, Firmicutes phylotypes such as Parageobacillus, Carboxydocella, Caldanaerobacter, and Carboxydothermus were found in different environmental conditions and distinct microbial communities. The relative abundance of the potential thermophilic hydrogenogenic carboxydotrophs was low. Most of them did not show any symbiotic networks with other microbes, implying that their metabolic activities might be low.
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Affiliation(s)
- Kimiho Omae
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8503, Japan
| | - Yuto Fukuyama
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8503, Japan
| | - Hisato Yasuda
- Center for Advanced Marine Core Research, Kochi University, B200 Monobe, Nankoku, Kochi, 783-8502, Japan
| | - Kenta Mise
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8503, Japan
| | - Takashi Yoshida
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8503, Japan
| | - Yoshihiko Sako
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8503, Japan.
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Fan YY, Li BB, Yang ZC, Cheng YY, Liu DF, Yu HQ. Abundance and diversity of iron reducing bacteria communities in the sediments of a heavily polluted freshwater lake. Appl Microbiol Biotechnol 2018; 102:10791-10801. [PMID: 30334090 DOI: 10.1007/s00253-018-9443-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 08/19/2018] [Accepted: 10/07/2018] [Indexed: 12/27/2022]
Abstract
Iron reduction mediated by Fe(III)-reducing bacteria (FeRB) occurs in aqueous environments and plays an essential role in removing contaminates in polluted freshwater lakes. Two model FeRB species, Shewanella and Geobacter, have been intensively studied because of their functions in bioremediation, iron reduction, and bioelectricity production. However, the abundance and community diversity of Shewanella and Geobacter in eutrophic freshwater lakes remain largely unknown. In this work, the distribution, abundance and biodiversity of Shewanella, Geobacter and other FeRB in the sediments of a heavily polluted lake, Chaohu Lake, China, across four successive seasons were investigated. Shewanella, Geobacter, and other FeRB were found to be widely distributed in the sediment of this heavily eutrophic lake. Geobacter was abundant with at least one order of magnitude more than Shewanella in cold seasons. Three Shewanella-related operational taxonomic units were detected and sixty one Geobacter-related operational taxonomic units were grouped into three phylogenetic clades. Thiobacillus, Desulfuromonas and Geobacter were identified as the main members of FeRB in the lake sediments. Interestingly, nutrients like carbon, nitrogen, and phosphorus were found to be the key factors governing the abundance and diversity of FeRB. Total FeRB, as well as Geobacter and Shewanella, were more abundant in the heavily eutrophic zone than those in the lightly eutrophic zone. The abundance and diversity of FeRB in the sediments of freshwater lakes were highly related with the degree of eutrophication, which imply that FeRB might have a great potential in alleviating the eutrophication and contamination in aqueous environments.
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Affiliation(s)
- Yang-Yang Fan
- School of Life Sciences, University of Science & Technology of China, Hefei, 230026, China
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, Hefei, 230026, China
| | - Bing-Bing Li
- School of Life Sciences, University of Science & Technology of China, Hefei, 230026, China
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, Hefei, 230026, China
| | - Zong-Chuang Yang
- School of Life Sciences, University of Science & Technology of China, Hefei, 230026, China
| | - Yuan-Yuan Cheng
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, Hefei, 230026, China
| | - Dong-Feng Liu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, Hefei, 230026, China.
| | - Han-Qing Yu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, Hefei, 230026, China
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Wang Y, Yu Q, Mishra B, Schaefer JK, Fein JB, Yee N. Adsorption of Methylmercury onto Geobacter bemidijensis Bem. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:11564-11572. [PMID: 30207459 DOI: 10.1021/acs.est.8b01987] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The anaerobic bacterium Geobacter bemidijensis Bem has the unique ability to both produce and degrade methylmercury (MeHg). While the adsorption of MeHg onto bacterial surfaces can affect the release of MeHg into aquatic environments as well as the uptake of MeHg for demethylation, the binding of MeHg to the bacterial envelope remains poorly understood. In this study, we quantified the adsorption of MeHg onto G. bemidijensis and applied X-ray absorption spectroscopy (XAS) to elucidate the mechanism of MeHg binding. The results showed MeHg adsorption onto G. bemidijensis cell surfaces was rapid and occurred via complexation to sulfhydryl functional groups. Titration experiments yielded cell surface sulfhydryl concentrations of 3.8 ± 0.2 μmol/g (wet cells). A one-site adsorption model with MeHg binding onto sulfhydryl sites provided excellent fits to adsorption isotherms conducted at different cell densities. The log K binding constant of MeHg onto the sulfhydryl sites was determined to be 10.5 ± 0.4. These findings provide a quantitative framework to describe MeHg binding onto bacterial cell surfaces and elucidate the importance of bacterial cells as possible carriers of adsorbed MeHg in natural aquatic systems.
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Affiliation(s)
- Yuwei Wang
- Department of Environmental Sciences , Rutgers University , New Brunswick , New Jersey 08901 , United States
| | - Qiang Yu
- Department of Civil & Environmental Engineering & Earth Sciences , University of Notre Dame , Notre Dame , Indiana 46556 , United States
| | - Bhoopesh Mishra
- School of Chemical and Process Engineering , University of Leeds , Leeds LS2 9JT , United Kingdom
| | - Jeffra K Schaefer
- Department of Environmental Sciences , Rutgers University , New Brunswick , New Jersey 08901 , United States
| | - Jeremy B Fein
- Department of Civil & Environmental Engineering & Earth Sciences , University of Notre Dame , Notre Dame , Indiana 46556 , United States
| | - Nathan Yee
- Department of Environmental Sciences , Rutgers University , New Brunswick , New Jersey 08901 , United States
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Torres K, Álvarez-Hornos FJ, San-Valero P, Gabaldón C, Marzal P. Granulation and microbial community dynamics in the chitosan-supplemented anaerobic treatment of wastewater polluted with organic solvents. WATER RESEARCH 2018; 130:376-387. [PMID: 29258049 DOI: 10.1016/j.watres.2017.12.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 12/05/2017] [Accepted: 12/07/2017] [Indexed: 06/07/2023]
Abstract
The effect of chitosan on the development of granular sludge in upflow anaerobic sludge blanket reactors (UASB) when treating wastewater polluted with the organic solvents ethanol, ethyl acetate, and 1-ethoxy-2-propanol was evaluated. Three UASB reactors were operated for 219 days at ambient temperature with an organic loading rate (OLR) of between 0.3 kg COD m-3 d-1 and 20 kg COD m-3 d-1. One reactor was operated without the addition of chitosan, while the other two were operated with the addition of chitosan doses of 2.4 mg gVSS-1 two times. The three reactors were all able to treat the OLR tested with COD removal efficiencies greater than 90%. However, the time required to reach stable operation was considerably reduced in the chitosan-assisted reactors. The development of granules in the reactors with chitosan was accelerated and granules larger than 2000 μm were only observed in these reactors. In addition, these granules exhibited better physicochemical characteristics: the mean particle diameter (540 and 613 μm) was approximately two times greater than in the control reactor (300 μm), and the settling velocities exceeded 35 m h-1. The extracellular polymeric substances (EPS) in the reactors with the chitosan was found to be higher than in the control reactor. The protein-EPS content has been correlated with the granule size. The analyses of the microbial communities, performed through denaturing gradient gel electrophoresis and high-throughput sequencing, revealed that the syntrophic microorganisms belonging to genus Geobacter and the hydrogenotrophic methanogen Methanocorpusculum labreanum were predominant in the granules. Other methanogens like Methanosaeta species were found earlier in the chitosan-assisted reactors than in the control reactor.
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Affiliation(s)
- K Torres
- Research Group on Environmental Engineering (GI(2)AM), Department of Chemical Engineering, Universitat de València, Av. de la Universitat s/n, 46100, Burjassot, Spain
| | - F J Álvarez-Hornos
- Research Group on Environmental Engineering (GI(2)AM), Department of Chemical Engineering, Universitat de València, Av. de la Universitat s/n, 46100, Burjassot, Spain
| | - P San-Valero
- Research Group on Environmental Engineering (GI(2)AM), Department of Chemical Engineering, Universitat de València, Av. de la Universitat s/n, 46100, Burjassot, Spain
| | - C Gabaldón
- Research Group on Environmental Engineering (GI(2)AM), Department of Chemical Engineering, Universitat de València, Av. de la Universitat s/n, 46100, Burjassot, Spain
| | - P Marzal
- Research Group on Environmental Engineering (GI(2)AM), Department of Chemical Engineering, Universitat de València, Av. de la Universitat s/n, 46100, Burjassot, Spain.
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Lund AL, Slater LD, Atekwana EA, Ntarlagiannis D, Cozzarelli I, Bekins BA. Evidence of Coupled Carbon and Iron Cycling at a Hydrocarbon-Contaminated Site from Time Lapse Magnetic Susceptibility. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:11244-11249. [PMID: 28872856 DOI: 10.1021/acs.est.7b02155] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Conventional characterization and monitoring of hydrocarbon (HC) pollution is often expensive and time-consuming. Magnetic susceptibility (MS) has been proposed as an inexpensive, long-term monitoring proxy of the degradation of HC. We acquired repeated down hole MS logging data in boreholes at a HC-contaminated field research site in Bemidji, MN, USA. The MS data were analyzed in conjunction with redox conditions and iron availability within the source zone to better assess whether MS can serve as a proxy for monitoring HC contamination in unconsolidated sediments. The MS response at the site diminished during the sampling period, which was found to coincide with depletion of solid phase iron in the source zone. Previous geochemical observations and modeling at the site suggest that the most likely cause of the decrease in MS is the transformation of magnetite to siderite, coupled with the exhaustion of ferrihydrite. Although the temporal MS response at this site gives valuable field-scale evidence for changing conditions of iron cycling and stability of iron minerals it does not provide a simple proxy for long-term monitoring of biodegradation of hydrocarbons in the smear zone.
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Affiliation(s)
- Anders L Lund
- Rutgers University Newark , Newark, New Jersey 07102, United States
- University of Aarhus , 8000 Aarhus, Denmark
| | - Lee D Slater
- Rutgers University Newark , Newark, New Jersey 07102, United States
| | - Estella A Atekwana
- Oklahoma State University , Main Campus, Stillwater, Oklahoma 74074, United States
| | | | - Isabelle Cozzarelli
- National Research Program, U.S. Geological Survey , Reston, Virginia 20192, United States
| | - Barbara A Bekins
- National Research Program, U.S. Geological Survey , Menlo Park, California 94025, United States
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Yilmazel YD, Zhu X, Kim KY, Holmes DE, Logan BE. Electrical current generation in microbial electrolysis cells by hyperthermophilic archaea Ferroglobus placidus and Geoglobus ahangari. Bioelectrochemistry 2017; 119:142-149. [PMID: 28992595 DOI: 10.1016/j.bioelechem.2017.09.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 09/27/2017] [Accepted: 09/28/2017] [Indexed: 02/07/2023]
Abstract
Few microorganisms have been examined for current generation under thermophilic (40-65°C) or hyperthermophilic temperatures (≥80°C) in microbial electrochemical systems. Two iron-reducing archaea from the family Archaeoglobaceae, Ferroglobus placidus and Geoglobus ahangari, showed electro-active behavior leading to current generation at hyperthermophilic temperatures in single-chamber microbial electrolysis cells (MECs). A current density (j) of 0.68±0.11A/m2 was attained in F. placidus MECs at 85°C, and 0.57±0.10A/m2 in G. ahangari MECs at 80°C, with an applied voltage of 0.7V. Cyclic voltammetry (CV) showed that both strains produced a sigmoidal catalytic wave, with a mid-point potential of -0.39V (vs. Ag/AgCl) for F. placidus and -0.37V for G. ahangari. The comparison of CVs using spent medium and turnover CVs, coupled with the detection of peaks at the same potentials in both turnover and non-turnover conditions, suggested that mediators were not used for electron transfer and that both archaea produced current through direct contact with the electrode. These two archaeal species, and other hyperthermophilic exoelectrogens, have the potential to broaden the applications of microbial electrochemical technologies for producing biofuels and other bioelectrochemical products under extreme environmental conditions.
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Affiliation(s)
- Yasemin D Yilmazel
- Department of Chemical Engineering, Rochester Institute of Technology, Rochester, NY, USA; Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA, USA.
| | - Xiuping Zhu
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA, USA; Department of Civil and Environmental Engineering, Louisiana State University, Baton Rouge, LA, USA
| | - Kyoung-Yeol Kim
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Dawn E Holmes
- Department of Biology, Western New England University, Springfield, MA, USA
| | - Bruce E Logan
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA, USA
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Zhao YG, Zhang Y, She Z, Shi Y, Wang M, Gao M, Guo L. Effect of Substrate Conversion on Performance of Microbial Fuel Cells and Anodic Microbial Communities. ENVIRONMENTAL ENGINEERING SCIENCE 2017; 34:666-674. [PMID: 28947873 PMCID: PMC5610400 DOI: 10.1089/ees.2016.0604] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 02/01/2017] [Indexed: 06/07/2023]
Abstract
Performance of microbial fuel cells (MFCs) was monitored during the influent nutrient change from lactate to glucose/acetate/propionate and then to lactate. Meanwhile, anodic microbial communities were characterized by culture-independent molecular biotechnologies. Results showed MFC performance recovered rapidly when the lactate was replaced by one of its metabolic intermediates acetate, while it needed a longer time to recover if lactate substrate was converted to glucose/propionate or acetate to lactate. Secondary lactate feed enhanced the enrichment of bacterial populations dominating in first lactate feed. Electricity-producing bacteria, Geobacter spp., and beneficial helpers, Anaeromusa spp. and Pseudomonas spp., revived from a low abundance as lactate secondary supply, but microbial communities were hard to achieve former profiles in structure and composition. Hence, microbial community profiles tended to recover when outside environmental condition were restored. Different substrates selected unique functional microbial populations.
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Affiliation(s)
- Yang-Guo Zhao
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, Ocean University of China, Qingdao, China
| | - Yi Zhang
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, Ocean University of China, Qingdao, China
| | - Zonglian She
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, Ocean University of China, Qingdao, China
| | - Yue Shi
- College of Power and Energy Engineering, Harbin Engineering University, Harbin, China
| | - Min Wang
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, Ocean University of China, Qingdao, China
| | - Mengchun Gao
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, Ocean University of China, Qingdao, China
| | - Liang Guo
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, Ocean University of China, Qingdao, China
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Eyiuche NJ, Asakawa S, Yamashita T, Ikeguchi A, Kitamura Y, Yokoyama H. Community analysis of biofilms on flame-oxidized stainless steel anodes in microbial fuel cells fed with different substrates. BMC Microbiol 2017; 17:145. [PMID: 28662640 PMCID: PMC5492815 DOI: 10.1186/s12866-017-1053-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 06/18/2017] [Indexed: 02/01/2023] Open
Abstract
Background The flame-oxidized stainless steel anode (FO-SSA) is a newly developed electrode that enhances microbial fuel cell (MFC) power generation; however, substrate preference and community structure of the biofilm developed on FO-SSA have not been well characterized. Herein, we investigated the community on FO-SSA using high-throughput sequencing of the 16S rRNA gene fragment in acetate-, starch-, glucose-, and livestock wastewater-fed MFCs. Furthermore, to analyze the effect of the anode material, the acetate-fed community formed on a common carbon-based electrode—carbon-cloth anode (CCA)—was examined for comparison. Results Substrate type influenced the power output of MFCs using FO-SSA; the highest electricity was generated using acetate as a substrate, followed by peptone, starch and glucose, and wastewater. Intensity of power generation using FO-SSA was related to the abundance of exoelectrogenic genera, namely Geobacter and Desulfuromonas, of the phylum Proteobacteria, which were detected at a higher frequency in acetate-fed communities than in communities fed with other substrates. Lactic acid bacteria (LAB)—Enterococcus and Carnobacterium—were predominant in starch- and glucose-fed communities, respectively. In the wastewater-fed community, members of phylum Planctomycetes were frequently detected (36.2%). Exoelectrogenic genera Geobacter and Desulfuromonas were also detected in glucose-, starch-, and wastewater-fed communities on FO-SSA, but with low frequency (0–3.2%); the lactate produced by Carnobacterium and Enterococcus in glucose- and starch-fed communities might affect exoelectrogenic bacterial growth, resulting in low power output by MFCs fed with these substrates. Furthermore, in the acetate-fed community on FO-SSA, Desulfuromonas was abundant (15.4%) and Geobacter had a minor proportion (0.7%), while in that on CCA, both Geobacter and Desulfuromonas were observed at similar frequencies (6.0–9.8%), indicating that anode material affects exoelectrogenic genus enrichment in anodic biofilm. Conclusions Anodic community structure was dependent on both substrate and anode material. Although Desulfuromonas spp. are marine microorganisms, they were abundant in the acetate-fed community on FO-SSA, implying the presence of novel non-halophilic and exoelectrogenic species in this genus. Power generation using FO-SSA was positively related to the frequency of exoelectrogenic genera in the anodic community. Predominant LAB in saccharide-fed anodic biofilm caused low abundance of exoelectrogenic genera and consequent low power generation.
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Affiliation(s)
- Nweze Julius Eyiuche
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan.,Department of Microbiology, University of Nigeria, Nsukka, Enugu State, 400241, Nigeria
| | - Shiho Asakawa
- Faculty of Agriculture, Utsunomiya University, 350 Minemachi, Utsunomiya, 321-8505, Japan
| | - Takahiro Yamashita
- Division of Animal Environment and Waste Management Research, Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization (NARO), 2 Ikenodai, Tsukuba, 305-0901, Japan
| | - Atsuo Ikeguchi
- Faculty of Agriculture, Utsunomiya University, 350 Minemachi, Utsunomiya, 321-8505, Japan
| | - Yutaka Kitamura
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan
| | - Hiroshi Yokoyama
- Division of Animal Environment and Waste Management Research, Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization (NARO), 2 Ikenodai, Tsukuba, 305-0901, Japan.
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The Influence of Micro-Oxygen Addition on Desulfurization Performance and Microbial Communities during Waste-Activated Sludge Digestion in a Rusty Scrap Iron-Loaded Anaerobic Digester. ENERGIES 2017. [DOI: 10.3390/en10020258] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Tkach O, Sangeetha T, Maria S, Wang A. Performance of low temperature Microbial Fuel Cells (MFCs) catalyzed by mixed bacterial consortia. J Environ Sci (China) 2017; 52:284-292. [PMID: 28254049 DOI: 10.1016/j.jes.2016.11.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Revised: 08/03/2016] [Accepted: 11/08/2016] [Indexed: 06/06/2023]
Abstract
Microbial Fuel Cells (MFCs) are a promising technology for treating wastewater in a sustainable manner. In potential applications, low temperatures substantially reduce MFC performance. To better understand the effect of temperature and particularly how bioanodes respond to changes in temperature, we investigated the current generation of mixed-culture and pure-culture MFCs at two low temperatures, 10°C and 5°C. The results implied that the mixed-culture MFC sustainably performed better than the pure-culture (Shewanella) MFC at 10°C, but the electrogenic activity of anodic bacteria was substantially reduced at the lower temperature of 5°C. At 10°C, the maximum output voltage generated with the mixed-culture was 540-560mV, which was 10%-15% higher than that of Shewanella MFCs. The maximum power density reached 465.3±5.8mW/m2 for the mixed-culture at 10°C, while only 68.7±3.7mW/m2 was achieved with the pure-culture. It was shown that the anodic biofilm of the mixed-culture MFC had a lower overpotential and resistance than the pure-culture MFC. Phylogenetic analysis disclosed the prevalence of Geobacter and Pseudomonas rather than Shewanella in the mixed-culture anodic biofilm, which mitigated the increase of resistance or overpotential at low temperatures.
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Affiliation(s)
- Olga Tkach
- State Key Laboratory of Urban Water Resources and Environment (SKLUWRE), Harbin Institute of Technology, Harbin 150090, China.
| | - Thangavel Sangeetha
- State Key Laboratory of Urban Water Resources and Environment (SKLUWRE), Harbin Institute of Technology, Harbin 150090, China.
| | - Spiridonova Maria
- Krasnoyarsk State Institution of Railway Vehicles, Krasnoyarsk 660028, Russia
| | - Aijie Wang
- State Key Laboratory of Urban Water Resources and Environment (SKLUWRE), Harbin Institute of Technology, Harbin 150090, China; Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
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Kato S. Influence of Anode Potentials on Current Generation and Extracellular Electron Transfer Paths of Geobacter Species. Int J Mol Sci 2017; 18:ijms18010108. [PMID: 28067820 PMCID: PMC5297742 DOI: 10.3390/ijms18010108] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 12/28/2016] [Accepted: 01/04/2017] [Indexed: 11/21/2022] Open
Abstract
Geobacter species are capable of utilizing solid-state compounds, including anodic electrodes, as electron acceptors of respiration via extracellular electron transfer (EET) and have attracted considerable attention for their crucial role as biocatalysts of bioelectrochemical systems (BES’s). Recent studies disclosed that anode potentials affect power output and anodic microbial communities, including selection of dominant Geobacter species, in various BES’s. However, the details in current-generating properties and responses to anode potentials have been investigated only for a model species, namely Geobacter sulfurreducens. In this study, the effects of anode potentials on the current generation and the EET paths were investigated by cultivating six Geobacter species with different anode potentials, followed by electrochemical analyses. The electrochemical cultivation demonstrated that the G. metallireducens clade species (G. sulfurreducens and G. metallireducens) constantly generate high current densities at a wide range of anode potentials (≥−0.3 or −0.2 V vs. Ag/AgCl), while the subsurface clades species (G. daltonii, G. bemidjensis, G. chapellei, and G. pelophilus) generate a relatively large current only at limited potential regions (−0.1 to −0.3 V vs. Ag/AgCl). The linear sweep voltammetry analyses indicated that the G. metallireducens clade species utilize only one EET path irrespective of the anode potentials, while the subsurface clades species utilize multiple EET paths, which can be optimized depending on the anode potentials. These results clearly demonstrate that the response features to anode potentials are divergent among species (or clades) of Geobacter.
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Affiliation(s)
- Souichiro Kato
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo, Hokkaido 062-8517, Japan.
- Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Kita-9 Nishi-9, Kita-ku, Sapporo, Hokkaido 060-8589, Japan.
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Ueno A, Shimizu S, Hashimoto M, Adachi T, Matsushita T, Okuyama H, Yoshida K. Effects of Aerobic Growth on the Fatty Acid and Hydrocarbon Compositions of Geobacter bemidjiensis Bem T. J Oleo Sci 2017; 66:93-101. [PMID: 27928141 DOI: 10.5650/jos.ess16122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Geobacter spp., regarded as strict anaerobes, have been reported to grow under aerobic conditions. To elucidate the role of fatty acids in aerobiosis of Geobacter spp., we studied the effect of aerobiosis on fatty acid composition and turnover in G. bemidjiensis BemT. G. bemidjiensis BemT was grown under the following different culture conditions: anaerobic culture for 4 days (type 1) and type 1 culture followed by 2-day anaerobic (type 2) or aerobic culture (anaerobic-to-aerobic shift; type 3). The mean cell weight of the type 3 culture was approximately 2.5-fold greater than that of type 1 and 2 cultures. The fatty acid methyl ester and hydrocarbon fraction contained hexadecanoic (16:0), 9-cis-hexadecenoic [16:1(9c)], tetradecanoic (14:0), tetradecenoic [14:1(7c)] acids, hentriacontanonaene, and hopanoids, but not long-chain polyunsaturated fatty acids. The type 3 culture contained higher levels of 14:0 and 14:1(7c) and lower levels of 16:0 and 16:1(9c) compared with type 1 and 2 cultures. The weight ratio of extracted lipid per dry cell was lower in the type 3 culture than in the type 1 and 2 cultures. We concluded that anaerobically-grown G. bemidjiensis BemT followed by aerobiosis were enhanced in growth, fatty acid turnover, and de novo fatty acid synthesis.
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Affiliation(s)
- Akio Ueno
- Horonobe Research Institute for the Subsurface Environment (H-RISE), NOASTEC
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Min UG, Kim SJ, Hong H, Kim SG, Gwak JH, Jung MY, Kim JG, Na JG, Rhee SK. Calculibacillus koreensis gen. nov., sp. nov., an anaerobic Fe(III)-reducing bacterium isolated from sediment of mine tailings. J Microbiol 2016; 54:413-9. [PMID: 27225457 DOI: 10.1007/s12275-016-6086-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/15/2016] [Accepted: 04/15/2016] [Indexed: 11/24/2022]
Abstract
A strictly anaerobic bacterium, strain B5(T), was isolated from sediment of an abandoned coal mine in Taebaek, Republic of Korea. Cells of strain B5(T) were non-spore-forming, straight, Gram-positive rods. The optimum pH and temperature for growth were pH 7.0 and 30°C, respectively, while the strain was able to grow within pH and temperature ranges of 5.5-7.5 and 25-45°C, respectively. Growth of strain B5(T) was observed at NaCl concentrations of 0 to 6.0% (w/v) with an optimum at 3.0-4.0% (w/v). The polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, an unknown phospholipid and three unknown polar lipids. Strain B5(T) grew anaerobically by reducing nitrate, nitrite, ferric-citrate, ferric-nitrilotriacetate, elemental sulfur, thiosulfate, and anthraquinone-2-sulfonate in the presence of proteinaceous compounds, organic acids, and carbohydrates as electron donors. The isolate was not able to grow by fermentation. Strain B5(T) did not grow under aerobic or microaerobic conditions. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain B5(T) is most closely related to the genus Tepidibacillus (T. fermentans STGH(T); 96.3%) and Vulcanibacillus (V. modesticaldus BR(T); 94.6%). The genomic DNA G+C content (36.9 mol%) of strain B5(T) was higher than those of T. fermentans STGH(T) (34.8 mol%) and V. modesticaldus BR(T) (34.5 mol%). Based on its phenotypic, chemotaxonomic, and phylogenetic properties, we describe a new species of a novel genus Calculibacillus, represented by strain B5(T) (=KCTC 15397(T) =JCM 19989(T)), for which we propose the name Calculibacillus koreensis gen. nov., sp. nov.
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Affiliation(s)
- Ui-Gi Min
- Department of Microbiology, Chungbuk National University, Cheongju, 54896, Republic of Korea
| | - So-Jeong Kim
- Department of Microbiology, Chungbuk National University, Cheongju, 54896, Republic of Korea
| | - Heeji Hong
- Department of Microbiology, Chungbuk National University, Cheongju, 54896, Republic of Korea
| | - Song-Gun Kim
- Microbial Resources Center/KCTC, Korea Research Institute of Bioscience and Biotechnology, Jeongeup, 56212, Republic of Korea
| | - Joo-Han Gwak
- Department of Microbiology, Chungbuk National University, Cheongju, 54896, Republic of Korea
| | - Man-Young Jung
- Department of Microbiology, Chungbuk National University, Cheongju, 54896, Republic of Korea
| | - Jong-Geol Kim
- Department of Microbiology, Chungbuk National University, Cheongju, 54896, Republic of Korea
| | - Jeong-Geol Na
- Biomass and Waste Energy Laboratory, Korea Institute of Energy Research, Daejeon, 34129, Republic of Korea
| | - Sung-Keun Rhee
- Department of Microbiology, Chungbuk National University, Cheongju, 54896, Republic of Korea.
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Lu X, Liu Y, Johs A, Zhao L, Wang T, Yang Z, Lin H, Elias DA, Pierce EM, Liang L, Barkay T, Gu B. Anaerobic Mercury Methylation and Demethylation by Geobacter bemidjiensis Bem. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:4366-73. [PMID: 27019098 DOI: 10.1021/acs.est.6b00401] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Microbial methylation and demethylation are two competing processes controlling the net production and bioaccumulation of neurotoxic methylmercury (MeHg) in natural ecosystems. Although mercury (Hg) methylation by anaerobic microorganisms and demethylation by aerobic Hg-resistant bacteria have both been extensively studied, little attention has been given to MeHg degradation by anaerobic bacteria, particularly the iron-reducing bacterium Geobacter bemidjiensis Bem. Here we report, for the first time, that the strain G. bemidjiensis Bem can mediate a suite of Hg transformations, including Hg(II) reduction, Hg(0) oxidation, MeHg production and degradation under anoxic conditions. Results suggest that G. bemidjiensis utilizes a reductive demethylation pathway to degrade MeHg, with elemental Hg(0) as the major reaction product, possibly due to the presence of genes encoding homologues of an organomercurial lyase (MerB) and a mercuric reductase (MerA). In addition, the cells can strongly sorb Hg(II) and MeHg, reduce or oxidize Hg, resulting in both time and concentration-dependent Hg species transformations. Moderate concentrations (10-500 μM) of Hg-binding ligands such as cysteine enhance Hg(II) methylation but inhibit MeHg degradation. These findings indicate a cycle of Hg methylation and demethylation among anaerobic bacteria, thereby influencing net MeHg production in anoxic water and sediments.
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Affiliation(s)
- Xia Lu
- School of Nuclear Science and Technology, Lanzhou University , Lanzhou, China
- Environmental Sciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Yurong Liu
- Environmental Sciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing, China
| | - Alexander Johs
- Environmental Sciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Linduo Zhao
- Environmental Sciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Tieshan Wang
- School of Nuclear Science and Technology, Lanzhou University , Lanzhou, China
| | - Ziming Yang
- Environmental Sciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Hui Lin
- Environmental Sciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Dwayne A Elias
- Biosciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Eric M Pierce
- Environmental Sciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Liyuan Liang
- Environmental Sciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
- Biology and Soft Matter Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Tamar Barkay
- Department of Biochemistry and Microbiology, Rutgers University , New Brunswick, New Jersey 08901, United States
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
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Md Khudzari J, Tartakovsky B, Raghavan GSV. Effect of C/N ratio and salinity on power generation in compost microbial fuel cells. WASTE MANAGEMENT (NEW YORK, N.Y.) 2016; 48:135-142. [PMID: 26611399 DOI: 10.1016/j.wasman.2015.11.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 11/10/2015] [Accepted: 11/10/2015] [Indexed: 05/15/2023]
Abstract
In this work, compost Microbial Fuel Cells (cMFCs) were used to generate electricity from a mix of fruit and vegetable wastes, and soil with different C/N ratios and salinities. Experiments were carried out in 500mL cMFCs equipped with carbon felt anodes and manganese dioxide cathodes. The cMFCs were loaded with fresh compost and operated at 20-23°C for up to 97days. The low C/N ratio (C/N 24) had a greater power production with a maximum power density of 5.29mW/m(2) (71.43mW/m(3)), indicating a more favorable condition for microbial growth. High-saline cMFCs produced lower power, suggesting that their level of salinity (10g/L of NaCl) inhibited electricigenic microorganisms. The closed-circuit cMFC showed an improved degradation of organic matter by 6% to 8% compared to the control MFC operated in an open circuit mode (no external resistor attached).
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Affiliation(s)
- Jauharah Md Khudzari
- Department of Bioresource Engineering, Macdonald Campus, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada
| | - Boris Tartakovsky
- National Research Council of Canada, 6100 Royalmount Avenue, Quebec H4P 2R2, Canada
| | - G S Vijaya Raghavan
- Department of Bioresource Engineering, Macdonald Campus, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada.
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45
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Ueoka N, Sese N, Sue M, Kouzuma A, Watanabe K. Sizes of Anode and Cathode Affect Electricity Generation in Rice Paddy-Field Microbial Fuel Cells. ACTA ACUST UNITED AC 2016. [DOI: 10.4236/jsbs.2016.61002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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46
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Fabisch M, Freyer G, Johnson CA, Büchel G, Akob DM, Neu TR, Küsel K. Dominance of 'Gallionella capsiferriformans' and heavy metal association with Gallionella-like stalks in metal-rich pH 6 mine water discharge. GEOBIOLOGY 2016; 14:68-90. [PMID: 26407813 DOI: 10.1111/gbi.12162] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 08/28/2015] [Indexed: 06/05/2023]
Abstract
Heavy metal-contaminated, pH 6 mine water discharge created new streams and iron-rich terraces at a creek bank in a former uranium-mining area near Ronneburg, Germany. The transition from microoxic groundwater with ~5 mm Fe(II) to oxic surface water may provide a suitable habitat for microaerobic iron-oxidizing bacteria (FeOB). In this study, we investigated the potential contribution of these FeOB to iron oxidation and metal retention in this high-metal environment. We (i) identified and quantified FeOB in water and sediment at the outflow, terraces, and creek, (ii) studied the composition of biogenic iron oxides (Gallionella-like twisted stalks) with scanning and transmission electron microscopy (SEM, TEM) as well as confocal laser scanning microscopy (CLSM), and (iii) examined the metal distribution in sediments. Using quantitative PCR, a very high abundance of FeOB was demonstrated at all sites over a 6-month study period. Gallionella spp. clearly dominated the communities, accounting for up to 88% of Bacteria, with a minor contribution of other FeOB such as Sideroxydans spp. and 'Ferrovum myxofaciens'. Classical 16S rRNA gene cloning showed that 96% of the Gallionella-related sequences had ≥ 97% identity to the putatively metal-tolerant 'Gallionella capsiferriformans ES-2', in addition to known stalk formers such as Gallionella ferruginea and Gallionellaceae strain R-1. Twisted stalks from glass slides incubated in water and sediment were composed of the Fe(III) oxyhydroxide ferrihydrite, as well as polysaccharides. SEM and scanning TEM-energy-dispersive X-ray spectroscopy revealed that stalk material contained Cu and Sn, demonstrating the association of heavy metals with biogenic iron oxides and the potential for metal retention by these stalks. Sequential extraction of sediments suggested that Cu (52-61% of total sediment Cu) and other heavy metals were primarily bound to the iron oxide fractions. These results show the importance of 'G. capsiferriformans' and biogenic iron oxides in slightly acidic but highly metal-contaminated freshwater environments.
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MESH Headings
- Aerobiosis
- Biota
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Ribosomal/chemistry
- DNA, Ribosomal/genetics
- Ferric Compounds/analysis
- Gallionellaceae/chemistry
- Gallionellaceae/classification
- Gallionellaceae/genetics
- Gallionellaceae/isolation & purification
- Germany
- Hydrogen-Ion Concentration
- Iron/metabolism
- Metals, Heavy/analysis
- Microscopy, Confocal
- Microscopy, Electrochemical, Scanning
- Microscopy, Electron, Transmission
- Molecular Sequence Data
- Oxidation-Reduction
- RNA, Ribosomal, 16S/genetics
- Sequence Analysis, DNA
- Water/chemistry
- Water Microbiology
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Affiliation(s)
- M Fabisch
- Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany
| | - G Freyer
- Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany
| | - C A Johnson
- Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany
- Department of Geosciences, Virginia Tech, Blacksburg, VA, USA
| | - G Büchel
- Institute of Geosciences, Friedrich Schiller University Jena, Jena, Germany
| | - D M Akob
- Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany
- U.S. Geological Survey, Reston, VA, USA
| | - T R Neu
- Department of River Ecology, Helmholtz Centre for Environmental Research Leipzig-Halle - UFZ, Magdeburg, Germany
| | - K Küsel
- Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
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47
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Commault AS, Lear G, Weld RJ. Maintenance of Geobacter -dominated biofilms in microbial fuel cells treating synthetic wastewater. Bioelectrochemistry 2015; 106:150-8. [DOI: 10.1016/j.bioelechem.2015.04.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Revised: 04/19/2015] [Accepted: 04/22/2015] [Indexed: 11/24/2022]
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48
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Miyahara M, Kouzuma A, Watanabe K. Effects of NaCl concentration on anode microbes in microbial fuel cells. AMB Express 2015; 5:123. [PMID: 26061773 PMCID: PMC4467806 DOI: 10.1186/s13568-015-0123-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 05/26/2015] [Indexed: 11/30/2022] Open
Abstract
Understanding of how operational parameters affect the composition of exoelectrogenic microbes is an important step in the development of efficient microbial fuel cells (MFCs). In the present study, single-chamber MFCs were inoculated with rice paddy-field soil and continuously supplied with an acetate medium containing different concentrations of NaCl (0–1.8 M). Polarization analyses showed that power output increased as the NaCl concentration increased to 0.1 M, while it was markedly diminished over 0.3 M. The increase in power output was associated with an increased abundance of anode microbes as assessed by protein assays. Notably, the power increase was also accompanied by an increase in the abundance ratio of Geobacter bacteria to total anode bacteria as assessed by pyrosequencing of 16S rRNA gene amplicons and specific quantitative PCR. Although most Geobacter species are known to exhibit high growth rates in freshwater media without NaCl, the present study shows that 0.1 M NaCl facilitates the growth of Geobacter in MFC anode biofilms. This result suggests that the optimum salt concentration in MFC is determined by the balance of two factors, namely, the solution conductivity and salt tolerance of exoelectrogens.
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49
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Morrissey EM, Franklin RB. Evolutionary history influences the salinity preference of bacterial taxa in wetland soils. Front Microbiol 2015; 6:1013. [PMID: 26483764 PMCID: PMC4591843 DOI: 10.3389/fmicb.2015.01013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 09/07/2015] [Indexed: 11/13/2022] Open
Abstract
Salinity is a major driver of bacterial community composition across the globe. Despite growing recognition that different bacterial species are present or active at different salinities, the mechanisms by which salinity structures community composition remain unclear. We tested the hypothesis that these patterns reflect ecological coherence in the salinity preferences of phylogenetic groups using a reciprocal transplant experiment of fresh- and saltwater wetland soils. The salinity of both the origin and host environments affected community composition (16S rRNA gene sequences) and activity (CO2 and CH4 production, and extracellular enzyme activity). These changes in community composition and activity rates were strongly correlated, which suggests the effect of environment on function could be mediated, at least in part, by microbial community composition. Based on their distribution across treatments, each phylotype was categorized as having a salinity preference (freshwater, saltwater, or none) and phylogenetic analyses revealed a significant influence of evolutionary history on these groupings. This finding was corroborated by examining the salinity preferences of high-level taxonomic groups. For instance, we found that the majority of α- and γ-proteobacteria in these wetland soils preferred saltwater, while many β-proteobacteria prefer freshwater. Overall, our results indicate the effect of salinity on bacterial community composition results from phylogenetically-clustered salinity preferences.
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Affiliation(s)
- Ember M Morrissey
- Laboratory of Microbial Ecology, Department of Biology, Virginia Commonwealth University Richmond, VA, USA
| | - Rima B Franklin
- Laboratory of Microbial Ecology, Department of Biology, Virginia Commonwealth University Richmond, VA, USA
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50
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Rotaru AE, Woodard TL, Nevin KP, Lovley DR. Link between capacity for current production and syntrophic growth in Geobacter species. Front Microbiol 2015; 6:744. [PMID: 26284037 PMCID: PMC4523033 DOI: 10.3389/fmicb.2015.00744] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 07/06/2015] [Indexed: 11/13/2022] Open
Abstract
Electrodes are unnatural electron acceptors, and it is yet unknown how some Geobacter species evolved to use electrodes as terminal electron acceptors. Analysis of different Geobacter species revealed that they varied in their capacity for current production. Geobacter metallireducens and G. hydrogenophilus generated high current densities (ca. 0.2 mA/cm(2)), comparable to G. sulfurreducens. G. bremensis, G. chapellei, G. humireducens, and G. uraniireducens, produced much lower currents (ca. 0.05 mA/cm(2)) and G. bemidjiensis was previously found to not produce current. There was no correspondence between the effectiveness of current generation and Fe(III) oxide reduction rates. Some high-current-density strains (G. metallireducens and G. hydrogenophilus) reduced Fe(III)-oxides as fast as some low-current-density strains (G. bremensis, G. humireducens, and G. uraniireducens) whereas other low-current-density strains (G. bemidjiensis and G. chapellei) reduced Fe(III) oxide as slowly as G. sulfurreducens, a high-current-density strain. However, there was a correspondence between the ability to produce higher currents and the ability to grow syntrophically. G. hydrogenophilus was found to grow in co-culture with Methanosarcina barkeri, which is capable of direct interspecies electron transfer (DIET), but not with Methanospirillum hungatei capable only of H2 or formate transfer. Conductive granular activated carbon (GAC) stimulated metabolism of the G. hydrogenophilus - M. barkeri co-culture, consistent with electron exchange via DIET. These findings, coupled with the previous finding that G. metallireducens and G. sulfurreducens are also capable of DIET, suggest that evolution to optimize DIET has fortuitously conferred the capability for high-density current production to some Geobacter species.
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Affiliation(s)
- Amelia-Elena Rotaru
- Department of Microbiology, University of Massachusetts Amherst, MA, USA ; Nordic Center for Earth Evolution, Department of Biology, University of Southern Denmark Odense, Denmark
| | - Trevor L Woodard
- Department of Microbiology, University of Massachusetts Amherst, MA, USA
| | - Kelly P Nevin
- Department of Microbiology, University of Massachusetts Amherst, MA, USA
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts Amherst, MA, USA
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