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Awala SI, Kim Y, Gwak JH, Seo C, Lee S, Kang M, Rhee SK. Methylococcus mesophilus sp. nov., the first non-thermotolerant methanotroph of the genus Methylococcus, from a rice field. Int J Syst Evol Microbiol 2023; 73. [PMID: 37824181 DOI: 10.1099/ijsem.0.006077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023] Open
Abstract
Strain 16-5T, a mesophilic methanotroph of the genus Methylococcus, was isolated from rice field soil sampled in Chungcheong Province, Republic of Korea. Strain 16-5T had both particulate and soluble methane monooxygenases and could only grow on methane and methanol as electron donors. Strain 16-5 T cells are Gram-negative, white to light tan in color, non-motile, non-flagellated, diplococcoid to cocci, and have the typical type I intracytoplasmic membrane system. Strain 16-5T grew at 18-38 °C (optimum, 27 °C) and at pH 5.0-8.0 (optimum, pH 6.5-7.0). C16 : 1 ω7c (38.8%), C16 : 1 ω5c (18.8%), C16 : 1 ω6c (16.8%) and C16 : 0 (16.9%) were the major fatty acids, and phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and an unidentified phospholipid were the major polar lipids. The main respiratory quinone was methylene-ubiquinone-8. Strain 16-5T displayed the highest 16S rRNA gene sequence similarities to other taxonomically recognized members of the genus Methylococcus, i.e. Methylococcus capsulatus TexasT (98.62%) and Methylococcus geothermalis IM1T (98.49 %), which were its closest relatives. It did, however, differ from all other taxonomically described Methylococcus species due to some phenotypic differences, most notably its inability to grow at temperatures above 38 °C, where other Methylococcus species thrive. Its 4.34 Mbp-sized genome has a DNA G+C content of 62.47 mol%, and multiple genome-based properties such as average nucleotide identity and digital DNA-DNA hybridization value distanced it from its closest relatives. Based on the data presented above, this strain represents the first non-thermotolerant species of the genus Methylococcus. The name Methylococcus mesophilus sp. nov. is proposed, and 16-5T (=JCM 35359T=KCTC 82050T) is the type strain.
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Affiliation(s)
- Samuel Imisi Awala
- Department of Microbiology, Chungbuk National University, Cheongju 28644, Republic of Korea
| | - Yongman Kim
- Department of Microbiology, Chungbuk National University, Cheongju 28644, Republic of Korea
| | - Joo-Han Gwak
- Department of Microbiology, Chungbuk National University, Cheongju 28644, Republic of Korea
| | - Chanmee Seo
- Department of Microbiology, Chungbuk National University, Cheongju 28644, Republic of Korea
| | - Seungki Lee
- National Institute of Biological Resources, Incheon 22689, Republic of Korea
| | - Minseo Kang
- Department of Microbiology, Chungbuk National University, Cheongju 28644, Republic of Korea
| | - Sung-Keun Rhee
- Department of Microbiology, Chungbuk National University, Cheongju 28644, Republic of Korea
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Tikhonova EN, Suleimanov RZ, Oshkin IY, Konopkin AA, Fedoruk DV, Pimenov NV, Dedysh SN. Growing in Saltwater: Biotechnological Potential of Novel Methylotuvimicrobium- and Methylomarinum-like Methanotrophic Bacteria. Microorganisms 2023; 11:2257. [PMID: 37764101 PMCID: PMC10538026 DOI: 10.3390/microorganisms11092257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 09/02/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023] Open
Abstract
Methanotrophic bacteria that possess a unique ability of using methane as a sole source of carbon and energy have attracted considerable attention as potential producers of a single-cell protein. So far, this biotechnology implied using freshwater methanotrophs, although many regions of the world have limited freshwater resources. This study aimed at searching for novel methanotrophs capable of fast growth in saltwater comparable in composition with seawater. A methane-oxidizing microbial consortium containing Methylomarinum- and Methylotuvimicrobium-like methanotrophs was enriched from sediment from the river Chernavka (water pH 7.5, total salt content 30 g L-1), a tributary river of the hypersaline Lake Elton, southern Russia. This microbial consortium, designated Ch1, demonstrated stable growth on natural gas in a bioreactor in media with a total salt content of 23 to 35.9 g L-1 at a dilution rate of 0.19-0.21 h-1. The highest biomass yield of 5.8 g cell dry weight (CDW)/L with a protein content of 63% was obtained during continuous cultivation of the consortium Ch1 in a medium with a total salt content of 29 g L-1. Isolation attempts resulted in obtaining a pure culture of methanotrophic bacteria, strain Ch1-1. The 16S rRNA gene sequence of strain Ch1-1 displayed 97.09-97.24% similarity to the corresponding gene fragments of characterized representatives of Methylomarinum vadi, methanotrophs isolated from marine habitats. The genome of strain Ch1-1 was 4.8 Mb in size and encoded 3 rRNA operons, and about 4400 proteins. The genome contained the gene cluster coding for ectoine biosynthesis, which explains the ability of strain Ch1-1 to tolerate high salt concentration.
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Affiliation(s)
| | | | | | | | | | | | - Svetlana N. Dedysh
- Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow 119071, Russia; (E.N.T.); (R.Z.S.); (I.Y.O.); (A.A.K.); (D.V.F.); (N.V.P.)
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Houghton KM, Carere CR, Stott MB, McDonald IR. Thermophilic methane oxidation is widespread in Aotearoa-New Zealand geothermal fields. Front Microbiol 2023; 14:1253773. [PMID: 37720161 PMCID: PMC10502179 DOI: 10.3389/fmicb.2023.1253773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 08/16/2023] [Indexed: 09/19/2023] Open
Abstract
Geothermal areas represent substantial point sources for greenhouse gas emissions such as methane. While it is known that methanotrophic microorganisms act as a biofilter, decreasing the efflux of methane in most soils to the atmosphere, the diversity and the extent to which methane is consumed by thermophilic microorganisms in geothermal ecosystems has not been widely explored. To determine the extent of biologically mediated methane oxidation at elevated temperatures, we set up 57 microcosms using soils from 14 Aotearoa-New Zealand geothermal fields and show that moderately thermophilic (>40°C) and thermophilic (>60°C) methane oxidation is common across the region. Methane oxidation was detected in 54% (n = 31) of the geothermal soil microcosms tested at temperatures up to 75°C (pH 1.5-8.1), with oxidation rates ranging from 0.5 to 17.4 μmol g-1 d-1 wet weight. The abundance of known aerobic methanotrophs (up to 60.7% Methylacidiphilum and 11.2% Methylothermus) and putative anaerobic methanotrophs (up to 76.7% Bathyarchaeota) provides some explanation for the rapid rates of methane oxidation observed in microcosms. However, not all methane oxidation was attributable to known taxa; in some methane-consuming microcosms we detected methanotroph taxa in conditions outside of their known temperature range for growth, and in other examples, we observed methane oxidation in the absence of known methanotrophs through 16S rRNA gene sequencing. Both of these observations suggest unidentified methane oxidizing microorganisms or undescribed methanotrophic syntrophic associations may also be present. Subsequent enrichment cultures from microcosms yielded communities not predicted by the original diversity studies and showed rates inconsistent with microcosms (≤24.5 μmol d-1), highlighting difficulties in culturing representative thermophilic methanotrophs. Finally, to determine the active methane oxidation processes, we attempted to elucidate metabolic pathways from two enrichment cultures actively oxidizing methane using metatranscriptomics. The most highly expressed genes in both enrichments (methane monooxygenases, methanol dehydrogenases and PqqA precursor peptides) were related to methanotrophs from Methylococcaceae, Methylocystaceae and Methylothermaceae. This is the first example of using metatranscriptomics to investigate methanotrophs from geothermal environments and gives insight into the metabolic pathways involved in thermophilic methanotrophy.
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Affiliation(s)
- Karen M. Houghton
- Te Pū Ao | GNS Science, Wairakei Research Centre, Taupō, New Zealand
- Te Aka Mātuatua | School of Science, Te Whare Wānanga o Waikato | University of Waikato, Hamilton, New Zealand
| | - Carlo R. Carere
- Te Pū Ao | GNS Science, Wairakei Research Centre, Taupō, New Zealand
- Te Tari Pūhanga Tukanga Matū | Department of Chemical and Process Engineering, Te Whare Wānanga o Waitaha | University of Canterbury, Christchurch, New Zealand
| | - Matthew B. Stott
- Te Pū Ao | GNS Science, Wairakei Research Centre, Taupō, New Zealand
- Te Kura Pūtaiao Koiora | School of Biological Sciences, Te Whare Wānanga o Waitaha | University of Canterbury, Christchurch, New Zealand
| | - Ian R. McDonald
- Te Aka Mātuatua | School of Science, Te Whare Wānanga o Waikato | University of Waikato, Hamilton, New Zealand
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Tan Y, Stein LY, Sauvageau D. Methanol bioconversion in Methylotuvimicrobium buryatense 5GB1C through self-cycling fermentation. Bioprocess Biosyst Eng 2023:10.1007/s00449-023-02876-3. [PMID: 37160768 DOI: 10.1007/s00449-023-02876-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 04/18/2023] [Indexed: 05/11/2023]
Abstract
Methanol is an abundant and low-cost next-generation carbon source. While many species of methanotrophic bacteria can convert methanol into valuable bioproducts in bioreactors, Methylotuvimicrobium buryatense 5GB1C stands out as one of the most promising strains for industrialization. It has a short doubling time compared to most methanotrophs, remarkable resilience against contamination, and a suite of tools enabling genetic engineering. When approaching industrial applications, growing M. buryatense 5GB1C on methanol using common batch reactor operation has important limitations; for example methanol toxicity leads to mediocre biomass productivity. Advanced bioreactor operation strategies, such as fed-batch and self-cycling fermentation, have the potential to greatly improve the industrial prospects of methanotrophs growing on methanol. Herein, implementation of fed-batch operation led to a 26-fold increase in biomass density, while two different self-cycling fermentation (SCF) strategies led to 3-fold and 10-fold increases in volumetric biomass productivity. Interestingly, while synchronization is a typical trait of microbial populations undergoing SCF, M. buryatense 5GB1C cultures growing under this mode of operation led to stable, reproducible cycles but no significant synchronization.
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Affiliation(s)
- Yusheng Tan
- Department of Chemical and Materials Engineering, University of Alberta, 9211-116 St. NW, Edmonton, AB, T6G 1H9, Canada
| | - Lisa Y Stein
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Dominic Sauvageau
- Department of Chemical and Materials Engineering, University of Alberta, 9211-116 St. NW, Edmonton, AB, T6G 1H9, Canada.
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Cre/ lox-Mediated CRISPRi Library Reveals Core Genome of a Type I Methanotroph Methylotuvimicrobium buryatense 5GB1C. Appl Environ Microbiol 2023; 89:e0188322. [PMID: 36622175 PMCID: PMC9888281 DOI: 10.1128/aem.01883-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Methanotrophs play key roles in global methane cycling and are promising platforms for methane bioconversion. However, major gaps existing in fundamental knowledge undermines understanding of these methane-consuming microorganisms. To associate genes with a phenotype at the genome-wide level, we developed a Cre/lox-mediated method for constructing a large-scale CRISPRi library in a model methanotroph Methylotuvimicrobium buryatense 5GB1C. The efficiency of this Cre mediated integration method was up to a level of 105 CFU/μg DNA. Targeting 4,100 predicted protein-coding genes, our CRISPRi pooled screening uncovered 788 core genes for the growth of strain 5GB1C using methane. The core genes are highly consistent with the gene knockout results, indicating the reliability of the CRISPRi screen. Insights from the core genes include that annotated isozymes generally exist in metabolic pathways and many core genes are hypothetical genes. This work not only provides functional genomic data for both fundamental research and metabolic engineering of methanotrophs, but also offers a method for CRISPRi library construction. IMPORTANCE Due to their key role in methane cycling and their industrial potential, methanotrophs have drawn increasing attention. Genome-wide experimental approaches for gene-phenotype mapping accelerate our understanding and engineering of a bacterium. However, these approaches are still unavailable in methanotrophs. This work has two significant implications. First, the core genes identified here provide functional genetic basics for complete reconstruction of the metabolic network and afford more clues for knowledge gaps. Second, the Cre-mediated knock-in method developed in this work enables large-scale DNA library construction in methanotrophs; the CRISPRi library can be used to screen the genes associated with special culture conditions.
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Yao X, Wang J, Hu B. How methanotrophs respond to pH: A review of ecophysiology. Front Microbiol 2023; 13:1034164. [PMID: 36687570 PMCID: PMC9853399 DOI: 10.3389/fmicb.2022.1034164] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 12/09/2022] [Indexed: 01/08/2023] Open
Abstract
Varying pH globally affects terrestrial microbial communities and biochemical cycles. Methanotrophs effectively mitigate methane fluxes in terrestrial habitats. Many methanotrophs grow optimally at neutral pH. However, recent discoveries show that methanotrophs grow in strongly acidic and alkaline environments. Here, we summarize the existing knowledge on the ecophysiology of methanotrophs under different pH conditions. The distribution pattern of diverse subgroups is described with respect to their relationship with pH. In addition, their responses to pH stress, consisting of structure-function traits and substrate affinity traits, are reviewed. Furthermore, we propose a putative energy trade-off model aiming at shedding light on the adaptation mechanisms of methanotrophs from a novel perspective. Finally, we take an outlook on methanotrophs' ecophysiology affected by pH, which would offer new insights into the methane cycle and global climate change.
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Affiliation(s)
- Xiangwu Yao
- Department of Environmental Engineering, Zhejiang University, Hangzhou, China
| | - Jiaqi Wang
- Department of Environmental Engineering, Zhejiang University, Hangzhou, China
| | - Baolan Hu
- Department of Environmental Engineering, Zhejiang University, Hangzhou, China,Zhejiang Province Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou, China,*Correspondence: Baolan Hu ✉
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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. [DOI: 10.1107/s2053230x22005088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [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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Bryanskaya AV, Shipova AA, Rozanov AS, Kolpakova OA, Lazareva EV, Uvarova YE, Efimov VM, Zhmodik SM, Taran OP, Goryachkovskaya TN, Peltek SE. Diversity and Metabolism of Microbial Communities in a Hypersaline Lake along a Geochemical Gradient. BIOLOGY 2022; 11:biology11040605. [PMID: 35453804 PMCID: PMC9031644 DOI: 10.3390/biology11040605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/13/2022] [Accepted: 04/14/2022] [Indexed: 11/16/2022]
Abstract
In the south of western Siberia (Russia), there are many unique and unexplored soda, saline, and freshwater lakes. In this study, the results are presented on microbial diversity, its metabolic potential, and their relation with a set of geochemical parameters for a hypersaline lake ecosystem in the Novosibirsk region (Oblast). The metagenomic approach used in this work allowed us to determine the composition and structure of a floating microbial community, the upper layer of silt, and the strata of bottom sediments in a natural saline lake via two bioinformatic approaches, whose results are in good agreement with each other. In the floating microbial community and in the upper layers of the bottom sediment, bacteria of the Proteobacteria (Gammaproteobacteria), Cyanobacteria, and Bacteroidetes phyla were found to predominate. The lower layers were dominated by Proteobacteria (mainly Deltaproteobacteria), Gemmatimonadetes, Firmicutes, and Archaea. Metabolic pathways were reconstructed to investigate the metabolic potential of the microbial communities and other hypothetical roles of the microbial communities in the biogeochemical cycle. Relations between different taxa of microorganisms were identified, as was their potential role in biogeochemical transformations of C, N, and S in a comparative structural analysis that included various ecological niches.
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Affiliation(s)
- Alla V. Bryanskaya
- Laboratory of Molecular Biotechnologies, Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia; (A.A.S.); (A.S.R.); (O.A.K.); (Y.E.U.); efim (V.M.E.); (T.N.G.); (S.E.P.)
- Kurchatov Genomics Center, Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia
- Correspondence: or ; Tel.: +7-383-363-4963 (ext. 4120)
| | - Aleksandra A. Shipova
- Laboratory of Molecular Biotechnologies, Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia; (A.A.S.); (A.S.R.); (O.A.K.); (Y.E.U.); efim (V.M.E.); (T.N.G.); (S.E.P.)
- Kurchatov Genomics Center, Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia
| | - Alexei S. Rozanov
- Laboratory of Molecular Biotechnologies, Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia; (A.A.S.); (A.S.R.); (O.A.K.); (Y.E.U.); efim (V.M.E.); (T.N.G.); (S.E.P.)
- Kurchatov Genomics Center, Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia
| | - Oxana A. Kolpakova
- Laboratory of Molecular Biotechnologies, Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia; (A.A.S.); (A.S.R.); (O.A.K.); (Y.E.U.); efim (V.M.E.); (T.N.G.); (S.E.P.)
- Kurchatov Genomics Center, Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia
| | - Elena V. Lazareva
- V.S. Sobolev Institute of Geology and Mineralogy SB RAS, 630090 Novosibirsk, Russia; (E.V.L.); (S.M.Z.)
| | - Yulia E. Uvarova
- Laboratory of Molecular Biotechnologies, Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia; (A.A.S.); (A.S.R.); (O.A.K.); (Y.E.U.); efim (V.M.E.); (T.N.G.); (S.E.P.)
- Kurchatov Genomics Center, Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia
| | - Vadim M. Efimov
- Laboratory of Molecular Biotechnologies, Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia; (A.A.S.); (A.S.R.); (O.A.K.); (Y.E.U.); efim (V.M.E.); (T.N.G.); (S.E.P.)
- Kurchatov Genomics Center, Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia
| | - Sergey M. Zhmodik
- V.S. Sobolev Institute of Geology and Mineralogy SB RAS, 630090 Novosibirsk, Russia; (E.V.L.); (S.M.Z.)
| | - Oxana P. Taran
- FRC Krasnoyarsk Science Center SB RAS, Institute of Chemistry and Chemical Technology SB RAS, 660036 Krasnoyarsk, Russia;
| | - Tatyana N. Goryachkovskaya
- Laboratory of Molecular Biotechnologies, Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia; (A.A.S.); (A.S.R.); (O.A.K.); (Y.E.U.); efim (V.M.E.); (T.N.G.); (S.E.P.)
- Kurchatov Genomics Center, Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia
| | - Sergey E. Peltek
- Laboratory of Molecular Biotechnologies, Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia; (A.A.S.); (A.S.R.); (O.A.K.); (Y.E.U.); efim (V.M.E.); (T.N.G.); (S.E.P.)
- Kurchatov Genomics Center, Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia
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Carmona-Martínez AA, Marcos-Rodrigo E, Bordel S, Marín D, Herrero-Lobo R, García-Encina PA, Muñoz R. Elucidating the key environmental parameters during the production of ectoines from biogas by mixed methanotrophic consortia. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 298:113462. [PMID: 34365180 DOI: 10.1016/j.jenvman.2021.113462] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 07/06/2021] [Accepted: 07/31/2021] [Indexed: 05/12/2023]
Abstract
Anaerobic digestion (AD) is a robust biotechnology for the valorisation of organic waste into biogas. However, the rapid decrease in renewable electricity prices requires alternative uses of biogas. In this context, the engineering of innovative platforms for the bio-production of chemicals from CH4 has recently emerged. The extremolyte and osmoprotectant ectoine, with a market price of ~1000€/Kg, is the industrial flagship of CH4-based bio-chemicals. This work aimed at optimizing the accumulation of ectoines using mixed microbial consortia enriched from saline environments (a salt lagoon and a salt river) and activated sludge, and biogas as feedstock. The influence of NaCl (0, 3, 6, 9 and 12 %) and Na2WO4 (0, 35 and 70 μg L-1) concentrations and incubation temperature (15, 25 and 35 °C) on the stoichiometry and kinetics of the methanotrophic consortia was investigated. Consortia enriched from activated sludge at 15 °C accumulated the highest yields of ectoine and hydroxyectoine at 6 % NaCl (105.0 ± 27.2 and 24.2 ± 5.4 mgextremolyte gbiomass-1, respectively). The consortia enriched from the salt lagoon accumulated the highest yield of ectoine and hydroxyectoine at 9 % NaCl (56.6 ± 2.5 and 51.0 ± 2.0 mgextremolyte gbiomass-1, respectively) at 25 °C. The supplementation of tungsten to the cultivation medium did not impact on the accumulation of ectoines in any of the consortia. A molecular characterization of the enrichments revealed a relative abundance of ectoine-accumulating methanotrophs of 7-16 %, with Methylomicrobium buryatense and Methylomicrobium japanense as the main players in the bioconversion of methane into ectoine.
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Affiliation(s)
- Alessandro A Carmona-Martínez
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain
| | - Eva Marcos-Rodrigo
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain
| | - Sergio Bordel
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain
| | - David Marín
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain
| | - Raquel Herrero-Lobo
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain
| | - Pedro A García-Encina
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain
| | - Raúl Muñoz
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain.
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Rahalkar MC, Khatri K, Pandit P, Bahulikar RA, Mohite JA. Cultivation of Important Methanotrophs From Indian Rice Fields. Front Microbiol 2021; 12:669244. [PMID: 34539593 PMCID: PMC8447245 DOI: 10.3389/fmicb.2021.669244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 08/09/2021] [Indexed: 11/15/2022] Open
Abstract
Methanotrophs are aerobic to micro-aerophilic bacteria, which oxidize and utilize methane, the second most important greenhouse gas. The community structure of the methanotrophs in rice fields worldwide has been studied mainly using culture-independent methods. Very few studies have focused on culturing methanotrophs from rice fields. We developed a unique method for the cultivation of methanotrophs from rice field samples. Here, we used a modified dilute nitrate mineral salts (dNMS) medium, with two cycles of dilution till extinction series cultivation with prolonged incubation time, and used agarose in the solid medium. The cultivation approach resulted in the isolation of methanotrophs from seven genera from the three major groups: Type Ia (Methylomonas, Methylomicrobium, and Methylocucumis), Type Ib (Methylocaldum and Methylomagnum), and Type II (Methylocystis and Methylosinus). Growth was obtained till 10–6–10–8 dilutions in the first dilution series, indicating the culturing of dominant methanotrophs. Our study was supported by 16S rRNA gene-based next-generation sequencing (NGS) of three of the rice samples. Our analyses and comparison with the global scenario suggested that the cultured members represented the major detected taxa. Strain RS1, representing a putative novel species of Methylomicrobium, was cultured; and the draft genome sequence was obtained. Genome analysis indicated that RS1 represented a new putative Methylomicrobium species. Methylomicrobium has been detected globally in rice fields as a dominant genus, although no Methylomicrobium strains have been isolated from rice fields worldwide. Ours is one of the first extensive studies on cultured methanotrophs from Indian rice fields focusing on the tropical region, and a unique method was developed. A total of 29 strains were obtained, which could be used as models for studying methane mitigation from rice fields and for environmental and biotechnological applications.
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Affiliation(s)
- Monali C Rahalkar
- C2, Bioenergy Group, MACS Agharkar Research Institute, Pune, India.,Department of Microbiology, Savitribai Phule Pune University, Pune, India
| | - Kumal Khatri
- C2, Bioenergy Group, MACS Agharkar Research Institute, Pune, India.,Department of Microbiology, Savitribai Phule Pune University, Pune, India
| | - Pranitha Pandit
- C2, Bioenergy Group, MACS Agharkar Research Institute, Pune, India.,Department of Microbiology, Savitribai Phule Pune University, Pune, India
| | - Rahul A Bahulikar
- Central Research Station, BAIF Development Research Foundation, Pune, India
| | - Jyoti A Mohite
- C2, Bioenergy Group, MACS Agharkar Research Institute, Pune, India.,Department of Microbiology, Savitribai Phule Pune University, Pune, India
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11
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Selection of methanotrophic platform for methanol production using methane and biogas. J Biosci Bioeng 2021; 132:460-468. [PMID: 34462232 DOI: 10.1016/j.jbiosc.2021.07.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 07/11/2021] [Accepted: 07/14/2021] [Indexed: 11/23/2022]
Abstract
To develop biotechnological process for methane to methanol conversion, selection of a suitable methanotrophic platform is an important aspect. Systematic approach based on literature and public databases was developed to select representative methanotrophs Methylotuvimicrobium alcaliphilum, Methylomonas methanica, Methylosinus trichosporium and Methylocella silvestris. Selected methanotrophs were further investigated for methanol tolerance and methanol production on pure methane as well as biogas along with key enzyme activities involved in methane utilization. Among selected methanotrophs M. alcaliphilum showed maximum methanol tolerance of 6% v/v along with maximum methanol production of 307.90 mg/L and 247.37 mg/L on pure methane and biogas respectively. Activity of methane monooxygenase and formate dehydrogenase enzymes in M.alcaliphilum was significantly higher up to 98.40 nmol/min/mg cells and 0.87 U/mg protein, respectively. Biotransformation trials in 14 L fermentor resulted in increased methanol production up to 418 and 331.20 mg/L, with yield coefficient 0.83 and 0.71 mg methanol/mg of pure methane and biogas respectively. The systematic selection resulted in haloalkaliphilic strain M. alcaliphilum as one of the potential methanotroph for bio-methanol production.
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12
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Microbial lipid biosynthesis from lignocellulosic biomass pyrolysis products. Biotechnol Adv 2021; 54:107791. [PMID: 34192583 DOI: 10.1016/j.biotechadv.2021.107791] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 05/18/2021] [Accepted: 06/24/2021] [Indexed: 01/08/2023]
Abstract
Lipids are a biorefinery platform to prepare fuel, food and health products. They are traditionally obtained from plants, but those of microbial origin allow for a better use of land and C resources, among other benefits. Several (thermo)chemical and biochemical strategies are used for the conversion of C contained in lignocellulosic biomass into lipids. In particular, pyrolysis can process virtually any biomass and is easy to scale up. Products offer cost-effective, renewable C in the form of readily fermentable molecules and other upgradable intermediates. Although the production of microbial lipids has been studied for 30 years, their incorporation into biorefineries was only described a few years ago. As pyrolysis becomes a profitable technology to depolymerize lignocellulosic biomass into assimilable C, the number of investigations on it raises significantly. This article describes the challenges and opportunities resulting from the combination of lignocellulosic biomass pyrolysis and lipid biosynthesis with oleaginous microorganisms. First, this work presents the basics of the individual processes, and then it shows state-of-the-art processes for the preparation of microbial lipids from biomass pyrolysis products. Advanced knowledge on separation techniques, structure analysis, and fermentability is detailed for each biomass pyrolysis fraction. Finally, the microbial fatty acid platform comprising biofuel, human food and animal feed products, and others, is presented. Literature shows that the microbial lipid production from anhydrosugars, like levoglucosan, and short-chain organic acids, like acetic acid, is straightforward. Indeed, processes achieving nearly theoretical yields form the latter have been described. Some authors have shown that lipid biosynthesis from different lignin sources is biochemically feasible. However, it still imposes major challenges regarding strain performance. No report on the fermentation of pyrolytic lignin is yet available. Research on the microbial uptake of pyrolytic humins remains vacant. Microorganisms that make use of methane show promising results at the proof-of-concept level. Overall, despite some issues need to be tackled, it is now possible to conceive new versatile biorefinery models by combining lignocellulosic biomass pyrolysis products and robust oleaginous microbial cell factories.
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13
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Jiang B, Zhang B, Li L, Zhao Y, Shi Y, Jiang Q, Jia L. Analysis of microbial community structure and diversity in surrounding rock soil of different waste dump sites in fushun western opencast mine. CHEMOSPHERE 2021; 269:128777. [PMID: 33189393 DOI: 10.1016/j.chemosphere.2020.128777] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 09/08/2020] [Accepted: 10/23/2020] [Indexed: 06/11/2023]
Abstract
It is importance to understand the correlation between the physicochemical properties of different surrounding rock soil and microbial communities in Fushun western opencast mining for the ecological restoration of land after mine closure. In this study, two layers of soil samples were collected from four different areas in Fushun western opencast mining: coal gangue area (CGA), green mudstone area (GMA), oil shale area (OSA) and mixed area (MA). Then, the effects of different surrounding rock soil physicochemical properties on the microbial communities were explored using the High-throughput sequencing technique. A wide diversity of taxonomical groups were present in four soil cores, and many were correlated with soil physicochemical properties. The obvious differences in microbial communities between different areas showed the influence of different surrounding rock soil on the microbial communities were significant. Redundancy analysis and the network diagram confirmed that soil physicochemical properties pH (Pondus Hydrogenii)-AN (Available Nitrogen)-EC (Electronic Conductivity)-WC (Water Content)-TK (Total Nitrogen), Cd (Cadmium)-Ni (Nickel) had great influence on the microbial communities. Therefore, this study can provide scientific judgments for the different surrounding rock soil physicochemical properties in coal mining, microbial-mediated rock mineralization and biogeochemical cycles.
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Affiliation(s)
- Binhui Jiang
- Northeastern University, School of Resources and Civil Engineering, Ministry of Education Safety Mining in Deep Metal Mines, Key Laboratory, Shenyang, 110819, China
| | - Bo Zhang
- Northeastern University, School of Resources and Civil Engineering, Ministry of Education Safety Mining in Deep Metal Mines, Key Laboratory, Shenyang, 110819, China
| | - Liang Li
- Northeastern University, School of Resources and Civil Engineering, Ministry of Education Safety Mining in Deep Metal Mines, Key Laboratory, Shenyang, 110819, China
| | - Yan Zhao
- Northeastern University, School of Resources and Civil Engineering, Ministry of Education Safety Mining in Deep Metal Mines, Key Laboratory, Shenyang, 110819, China
| | - Yang Shi
- Northeastern University, School of Resources and Civil Engineering, Ministry of Education Safety Mining in Deep Metal Mines, Key Laboratory, Shenyang, 110819, China
| | - Qi Jiang
- Northeastern University, School of Resources and Civil Engineering, Ministry of Education Safety Mining in Deep Metal Mines, Key Laboratory, Shenyang, 110819, China
| | - Liping Jia
- Northeastern University, School of Resources and Civil Engineering, Ministry of Education Safety Mining in Deep Metal Mines, Key Laboratory, Shenyang, 110819, China; College of Chemistry and Environmental Science, Minnan Normal University, Zhangzhou, 363000, China.
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14
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Groom JD, Lidstrom ME. Cultivation techniques to study lanthanide metal interactions in the haloalkaliphilic Type I methanotroph "Methylotuvimicrobium buryatense" 5GB1C. Methods Enzymol 2021; 650:237-259. [PMID: 33867024 DOI: 10.1016/bs.mie.2021.01.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Lanthanide metals are commonly used in technological devices including batteries, computers, catalysts and magnets. Despite their important properties, mining difficulties and pollution concerns limit the number of mines worldwide. Because of these concerns, biometallurgy is an attractive possibility for lanthanide extraction from recycled materials or from contaminated sites. Methylotrophs, bacteria that grow on reduced carbon substrates like methane and methanol, utilize lanthanides for a central reaction in their metabolisms. They must have some mechanism for uptake or trafficking, and are therefore excellent candidates for applying small molecules or proteins for selective lanthanide metal recycling. The haloalkaliphilic methanotroph "Methylotuvimicrobium buryatense" 5GB1C is the fastest growing methanotroph isolated to date, and thus has great industrial potential. The MxaFI enzyme complex uses calcium as a Lewis acid in conjunction with the pyroquinoline quinone cofactor to oxidize methanol, while the alternative enzyme XoxF uses lanthanide metals (e.g. lanthanum and cerium) for the same function. Lanthanide metals, abundant in the earth's crust, strongly repress the transcription of mxaF yet activate the transcription of xoxF, implying that XoxF may be the predominant methanol dehydrogenase in the bacterium's native environment. It may be that lanthanum interaction mechanisms are different from those in other microorganisms. In addition, the facile genetics in this strain and existing background information make it a good study organism for biological lanthanum uptake. The interesting physiology of this organism required empirical work to develop cultivation methods that allow robust assays of gene expression and measurement of lanthanum associated with cell biomass. In this chapter, we show that altering the metal chelator increased the availability of lanthanum to the cell as measured by the specific gene expression response. We also made further alterations to prevent lanthanum precipitation in medium for the growth of haloalkaliphiles.
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Affiliation(s)
- Joseph D Groom
- Department of Chemical Engineering, University of Washington, Seattle, WA, United States.
| | - Mary E Lidstrom
- Department of Chemical Engineering, University of Washington, Seattle, WA, United States; Department of Microbiology, University of Washington, Seattle, WA, United States
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15
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Jawaharraj K, Shrestha N, Chilkoor G, Dhiman SS, Islam J, Gadhamshetty V. Valorization of methane from environmental engineering applications: A critical review. WATER RESEARCH 2020; 187:116400. [PMID: 32979578 DOI: 10.1016/j.watres.2020.116400] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 07/29/2020] [Accepted: 09/05/2020] [Indexed: 05/09/2023]
Abstract
Wastewater and waste management sectors alone account for 18% of the anthropogenic methane (CH4) emissions. This study presents a critical overview of methanotrophs ("methane oxidizing microorganisms") for valorizing typically discarded CH4 from environmental engineering applications, focusing on wastewater treatment plants. Methanotrophs can convert CH4 into valuable bioproducts including chemicals, biodiesel, DC electricity, polymers, and S-layers, all under ambient conditions. As discarded CH4 and its oxidation products can also be used as a carbon source in nitrification and annamox processes. Here we discuss modes of CH4 assimilation by methanotrophs in both natural and engineered systems. We also highlight the technical challenges and technological breakthroughs needed to enable targeted CH4 oxidation in wastewater treatment plants.
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Affiliation(s)
- Kalimuthu Jawaharraj
- Civil and Environmental Engineering, South Dakota Mines, Rapid City 57701, SD, United States; BuG ReMeDEE consortium, South Dakota Mines, Rapid City 57701, SD, United States
| | - Namita Shrestha
- Civil and Environmental Engineering, Rose-Hulman Institute of Technology, Terre Haute 47803, IN, United States
| | - Govinda Chilkoor
- Civil and Environmental Engineering, South Dakota Mines, Rapid City 57701, SD, United States; 2-Dimensional Materials for Biofilm Engineering Science and Technology (2DBEST) Center, South Dakota School of Mines and Technology, Rapid City 57701, SD, United States
| | - Saurabh Sudha Dhiman
- BuG ReMeDEE consortium, South Dakota Mines, Rapid City 57701, SD, United States; Biological and Chemical Engineering, South Dakota School of Mines & Technology, Rapid City 57701, SD, United States
| | - Jamil Islam
- Civil and Environmental Engineering, South Dakota Mines, Rapid City 57701, SD, United States; BuG ReMeDEE consortium, South Dakota Mines, Rapid City 57701, SD, United States
| | - Venkataramana Gadhamshetty
- Civil and Environmental Engineering, South Dakota Mines, Rapid City 57701, SD, United States; BuG ReMeDEE consortium, South Dakota Mines, Rapid City 57701, SD, United States; 2-Dimensional Materials for Biofilm Engineering Science and Technology (2DBEST) Center, South Dakota School of Mines and Technology, Rapid City 57701, SD, United States.
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16
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Poghosyan L, Koch H, Frank J, van Kessel MAHJ, Cremers G, van Alen T, Jetten MSM, Op den Camp HJM, Lücker S. Metagenomic profiling of ammonia- and methane-oxidizing microorganisms in two sequential rapid sand filters. WATER RESEARCH 2020; 185:116288. [PMID: 32810745 DOI: 10.1016/j.watres.2020.116288] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/17/2020] [Accepted: 08/09/2020] [Indexed: 05/22/2023]
Abstract
Elevated concentrations of ammonium and methane in groundwater are often associated with microbiological, chemical and sanitary problems during drinking water production and distribution. To avoid their accumulation, raw water in the Netherlands and many other countries is purified by sand filtration. These drinking water filtration systems select for microbial communities that mediate the biodegradation of organic and inorganic compounds. In this study, the top layers and wall biofilm of a Dutch drinking water treatment plant (DWTP) were sampled from the filtration units of the plant over three years. We used high-throughput sequencing in combination with differential coverage and sequence composition-based binning to recover 56 near-complete metagenome-assembled genomes (MAGs) with an estimated completion of ≥70% and with ≤10% redundancy. These MAGs were used to characterize the microbial communities involved in the conversion of ammonia and methane. The methanotrophic microbial communities colonizing the wall biofilm (WB) and the granular material of the primary rapid sand filter (P-RSF) were dominated by members of the Methylococcaceae and Methylophilaceae. The abundance of these bacteria drastically decreased in the secondary rapid sand filter (S-RSF) samples. In all samples, complete ammonia-oxidizing (comammox) Nitrospira were the most abundant nitrifying guild. Clade A comammox Nitrospira dominated the P-RSF, while clade B was most abundant in WB and S-RSF, where ammonium concentrations were much lower. In conclusion, the knowledge obtained in this study contributes to understanding the role of microorganisms in the removal of carbon and nitrogen compounds during drinking water production. We furthermore found that drinking water treatment plants represent valuable model systems to study microbial community function and interaction.
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Affiliation(s)
- Lianna Poghosyan
- Department of Microbiology, Radboud University, Heyendaalseweg 135, Nijmegen 6525AJ, the Netherlands
| | - Hanna Koch
- Department of Microbiology, Radboud University, Heyendaalseweg 135, Nijmegen 6525AJ, the Netherlands
| | - Jeroen Frank
- Department of Microbiology, Radboud University, Heyendaalseweg 135, Nijmegen 6525AJ, the Netherlands
| | - Maartje A H J van Kessel
- Department of Microbiology, Radboud University, Heyendaalseweg 135, Nijmegen 6525AJ, the Netherlands
| | - Geert Cremers
- Department of Microbiology, Radboud University, Heyendaalseweg 135, Nijmegen 6525AJ, the Netherlands
| | - Theo van Alen
- Department of Microbiology, Radboud University, Heyendaalseweg 135, Nijmegen 6525AJ, the Netherlands
| | - Mike S M Jetten
- Department of Microbiology, Radboud University, Heyendaalseweg 135, Nijmegen 6525AJ, the Netherlands
| | - Huub J M Op den Camp
- Department of Microbiology, Radboud University, Heyendaalseweg 135, Nijmegen 6525AJ, the Netherlands
| | - Sebastian Lücker
- Department of Microbiology, Radboud University, Heyendaalseweg 135, Nijmegen 6525AJ, the Netherlands.
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17
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Nature and bioprospecting of haloalkaliphilics: a review. World J Microbiol Biotechnol 2020; 36:66. [DOI: 10.1007/s11274-020-02841-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 04/14/2020] [Indexed: 01/07/2023]
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18
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Saidi-Mehrabad A, Kits DK, Kim JJ, Tamas I, Schumann P, Khadka R, Strilets T, Smirnova AV, Rijpstra WIC, Sinninghe Damsté JS, Dunfield PF. Methylicorpusculum oleiharenae gen. nov., sp. nov., an aerobic methanotroph isolated from an oil sands tailings pond. Int J Syst Evol Microbiol 2020; 70:2499-2508. [DOI: 10.1099/ijsem.0.004064] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
An aerobic methane oxidizing bacterium, designated XLMV4T, was isolated from the oxic surface layer of an oil sands tailings pond in Alberta, Canada. Strain XLMV4T is capable of growth on methane and methanol as energy sources. NH4Cl and sodium nitrate are nitrogen sources. Cells are Gram-negative, beige to yellow-pigmented, motile (via a single polar flagellum), short rods 2.0–3.3 µm in length and 1.0–1.6 µm in width. A thick capsule is produced. Surface glycoprotein or cup shape proteins typical of the genera Methylococcus, Methylothermus and
Methylomicrobium
were not observed. Major isoprenoid quinones are Q-8 and Q-7 at an approximate molar ratio of 71 : 22. Major polar lipids are phosphoglycerol and ornithine lipids. Major fatty acids are C16 : 1 ω8+C16 : 1 ω7 (34 %), C16 : 1 ω5 (16 %), and C18 : 1 ω7 (11 %). Optimum growth is observed at pH 8.0 and 25 °C. The DNA G+C content based on a draft genome sequence is 46.7 mol%. Phylogenetic analysis of 16S rRNA genes and a larger set of conserved genes place strain XLMV4T within the class
Gammaproteobacteria
and family
Methylococcaceae
, most closely related to members of the genera
Methylomicrobium
and
Methylobacter
(95.0–97.1 % 16S rRNA gene sequence identity). In silico genomic predictions of DNA–DNA hybridization values of strain XLMV4T to the nearest phylogenetic neighbours were all below 26 %. On the basis of the data presented, strain XLMV4T is considered to represent a new genus and species for which the name Methylicorpusculum oleiharenae is proposed. Strain XLMV4T (=DSMZ DSM 27269=ATCC TSD-186) is the type strain.
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Affiliation(s)
- Alireza Saidi-Mehrabad
- Department of Biological Sciences, University of Alberta, 11455 Saskatchewan Drive, Edmonton, Alberta, T6G 2E9, Canada
- Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, Alberta, T2N 1N4, Canada
| | - Dimitri K. Kits
- Department of Biological Sciences, University of Alberta, 11455 Saskatchewan Drive, Edmonton, Alberta, T6G 2E9, Canada
| | - Joong-Jae Kim
- Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, Alberta, T2N 1N4, Canada
| | - Ivica Tamas
- Departman Za Biologiju I Ekologiju, Prirodno-Matematicki Fakultet, Univerzitet u Novom Sadu, Trg Dositeja Obradovića 2, 21000 Novi Sad, Serbia
- Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, Alberta, T2N 1N4, Canada
| | - Peter Schumann
- Leibniz Institute DSMZ German Collection of Microorganisms and Cell Cultures. Inhoffenstr. 7 B 38124 Braunschweig, Germany
| | - Roshan Khadka
- Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, Alberta, T2N 1N4, Canada
| | - Tania Strilets
- Department of Biological Sciences, University of Alberta, 11455 Saskatchewan Drive, Edmonton, Alberta, T6G 2E9, Canada
| | - Angela V. Smirnova
- Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, Alberta, T2N 1N4, Canada
| | - W. Irene C. Rijpstra
- Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, and Utrecht University, P.O. Box 59, 1790 AB, Den Burg, Texel, The Netherlands
| | - Jaap S. Sinninghe Damsté
- Faculty of Geosciences, Department of Earth Sciences, Utrecht University, P.O. Box 80.021, 3508 TA Utrecht, The Netherlands
- Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, and Utrecht University, P.O. Box 59, 1790 AB, Den Burg, Texel, The Netherlands
| | - Peter F. Dunfield
- Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, Alberta, T2N 1N4, Canada
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19
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Cho S, Ha S, Kim HS, Han JH, Kim H, Yeon YJ, Na JG, Lee J. Stimulation of cell growth by addition of tungsten in batch culture of a methanotrophic bacterium, Methylomicrobium alcaliphilum 20Z on methane and methanol. J Biotechnol 2020; 309:81-84. [PMID: 31899249 DOI: 10.1016/j.jbiotec.2019.12.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 12/12/2019] [Accepted: 12/31/2019] [Indexed: 11/15/2022]
Abstract
It is carried out for researches to convert methane, the second most potent greenhouse gas, to high-value chemicals and fuels by using methanotrophs. In this study, we observed that cell growth of Methylomicrobium alcaliphilum 20Z in the batch cultures on methane or methanol was stimulated by the addition of tungsten (W) without formate accumulation. Not only biomass yield but also the total products yield (biomass and formate) on carbon basis increased up to 11.50-fold and 1.28-fold respectively in W-added medium. Furthermore, a significant decrease in CO2 yield from formate was observed in the W-added cells, which indicates that W might have affected the activity of certain enzymes involved in carbon assimilation as well as formate dehydrogenase (FDH). The results of this study suggest that M. alcaliphilum 20Z is a promising model system for studying the physiology of the aerobic methanotroph and for enabling its industrial use for methane conversion through high cell density cultivation.
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Affiliation(s)
- Sukhyeong Cho
- C1 Gas Refinery R&D Center, Sogang University, Seoul, Republic of Korea
| | - Seonyoung Ha
- Department of Chemical and Biomolecular Engineering, Sogang University, Seoul, Republic of Korea
| | - Hye Su Kim
- C1 Gas Refinery R&D Center, Sogang University, Seoul, Republic of Korea
| | - Jin Hee Han
- C1 Gas Refinery R&D Center, Sogang University, Seoul, Republic of Korea
| | - Hyeonsoo Kim
- Department of Chemical and Biomolecular Engineering, Sogang University, Seoul, Republic of Korea
| | - Young Joo Yeon
- Department of Biochemical Engineering, Gangneung-Wonju National University, Gangneung, Republic of Korea
| | - Jeong Geol Na
- Department of Chemical and Biomolecular Engineering, Sogang University, Seoul, Republic of Korea
| | - Jinwon Lee
- C1 Gas Refinery R&D Center, Sogang University, Seoul, Republic of Korea; Department of Chemical and Biomolecular Engineering, Sogang University, Seoul, Republic of Korea.
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20
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Wang S, An Z, Wang ZW. Bioconversion of methane to chemicals and fuels by methane-oxidizing bacteria. ADVANCES IN BIOENERGY 2020. [DOI: 10.1016/bs.aibe.2020.04.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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21
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Hu L, Yang Y, Yan X, Zhang T, Xiang J, Gao Z, Chen Y, Yang S, Fei Q. Molecular Mechanism Associated With the Impact of Methane/Oxygen Gas Supply Ratios on Cell Growth of Methylomicrobium buryatense 5GB1 Through RNA-Seq. Front Bioeng Biotechnol 2020; 8:263. [PMID: 32318556 PMCID: PMC7154130 DOI: 10.3389/fbioe.2020.00263] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/13/2020] [Indexed: 11/13/2022] Open
Abstract
The methane (CH4)/oxygen (O2) gas supply ratios significantly affect the cell growth and metabolic pathways of aerobic obligate methanotrophs. However, few studies have explored the CH4/O2 ratios of the inlet gas, especially for the CH4 concentrations within the explosion range (5∼15% of CH4 in air). This study thoroughly investigated the molecular mechanisms associated with the impact of different CH4/O2 ratios on cell growth of a model type I methanotroph Methylomicrobium buryatense 5GB1 cultured at five different CH4/O2 supply molar ratios from 0.28 to 5.24, corresponding to CH4 content in gas mixture from 5% to 50%, using RNA-Seq transcriptomics approach. In the batch cultivation, the highest growth rate of 0.287 h-1 was achieved when the CH4/O2 supply molar ratio was 0.93 (15% CH4 in air), and it is crucial to keep the availability of carbon and oxygen levels balanced for optimal growth. At this ratio, genes related to methane metabolism, phosphate uptake system, and nitrogen fixation were significantly upregulated. The results indicated that the optimal CH4/O2 ratio prompted cell growth by increasing genes involved in metabolic pathways of carbon, nitrogen and phosphate utilization in M. buryatense 5GB1. Our findings provided an effective gas supply strategy for methanotrophs, which could enhance the production of key intermediates and enzymes to improve the performance of bioconversion processes using CH4 as the only carbon and energy source. This research also helps identify genes associated with the optimal CH4/O2 ratio for balancing energy metabolism and carbon flux, which could be candidate targets for future metabolic engineering practice.
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Affiliation(s)
- Lizhen Hu
- School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an, China
| | - Yongfu Yang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Environmental Microbial Technology Center of Hubei Province, and School of Life Sciences, Hubei University, Wuhan, China
| | - Xin Yan
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Tianqing Zhang
- School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an, China
| | - Jing Xiang
- School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an, China
| | - Zixi Gao
- School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an, China
| | - Yunhao Chen
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Environmental Microbial Technology Center of Hubei Province, and School of Life Sciences, Hubei University, Wuhan, China
| | - Shihui Yang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Environmental Microbial Technology Center of Hubei Province, and School of Life Sciences, Hubei University, Wuhan, China
- *Correspondence: Shihui Yang,
| | - Qiang Fei
- School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an, China
- Shaanxi Key Laboratory of Energy Chemical Process Intensification, Xi’an Jiaotong University, Xi’an, China
- Qiang Fei,
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Salt Tolerance Mechanism and Species Identification of the Plant Rhizosphere Bacterium JYZ-SD2. Curr Microbiol 2019; 77:388-395. [DOI: 10.1007/s00284-019-01835-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 11/29/2019] [Indexed: 12/13/2022]
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Quantifying Methane and Methanol Metabolism of " Methylotuvimicrobium buryatense" 5GB1C under Substrate Limitation. mSystems 2019; 4:4/6/e00748-19. [PMID: 31822604 PMCID: PMC6906744 DOI: 10.1128/msystems.00748-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Methanotrophic metabolism has been under investigation for decades using biochemical and genetic approaches. Recently, a further step has been taken toward understanding methanotrophic metabolism in a quantitative manner by means of flux balance analysis (FBA), a mathematical approach that predicts fluxes constrained by mass balance and a few experimental measurements. However, no study has previously been undertaken to experimentally quantitate the complete methanotrophic central metabolism. The significance of this study is to fill such a gap by performing 13C INST-MFA on a fast-growing methanotroph. Our quantitative insights into the methanotrophic carbon and energy metabolism will pave the way for future FBA studies and set the stage for rational design of methanotrophic strains for industrial applications. Further, the experimental strategies can be applied to other methane or methanol utilizers, and the results will offer a unique and quantitative perspective of diverse methylotrophic metabolism. Methanotrophic bacteria are a group of prokaryotes capable of using methane as their sole carbon and energy source. Although efforts have been made to simulate and elucidate their metabolism via computational approaches or 13C tracer analysis, major gaps still exist in our understanding of methanotrophic metabolism at the systems level. Particularly, direct measurements of system-wide fluxes are required to understand metabolic network function. Here, we quantified the central metabolic fluxes of a type I methanotroph, “Methylotuvimicrobium buryatense” 5GB1C, formerly Methylomicrobium buryatense 5GB1C, via 13C isotopically nonstationary metabolic flux analysis (INST-MFA). We performed labeling experiments on chemostat cultures by switching substrates from 12C to 13C input. Following the switch, we measured dynamic changes of labeling patterns and intracellular pool sizes of several intermediates, which were later used for data fitting and flux calculations. Through computational optimizations, we quantified methane and methanol metabolism at two growth rates (0.1 h−1 and 0.05 h−1). The resulting flux maps reveal a core consensus central metabolic flux phenotype across different growth conditions: a strong ribulose monophosphate cycle, a preference for the Embden-Meyerhof-Parnas pathway as the primary glycolytic pathway, and a tricarboxylic acid cycle showing small yet significant fluxes. This central metabolic consistency is further supported by a good linear correlation between fluxes at the two growth rates. Specific differences between methane and methanol growth observed previously are maintained under substrate limitation, albeit with smaller changes. The substrate oxidation and glycolysis pathways together contribute over 80% of total energy production, while other pathways play less important roles. IMPORTANCE Methanotrophic metabolism has been under investigation for decades using biochemical and genetic approaches. Recently, a further step has been taken toward understanding methanotrophic metabolism in a quantitative manner by means of flux balance analysis (FBA), a mathematical approach that predicts fluxes constrained by mass balance and a few experimental measurements. However, no study has previously been undertaken to experimentally quantitate the complete methanotrophic central metabolism. The significance of this study is to fill such a gap by performing 13C INST-MFA on a fast-growing methanotroph. Our quantitative insights into the methanotrophic carbon and energy metabolism will pave the way for future FBA studies and set the stage for rational design of methanotrophic strains for industrial applications. Further, the experimental strategies can be applied to other methane or methanol utilizers, and the results will offer a unique and quantitative perspective of diverse methylotrophic metabolism.
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Wehrmann M, Berthelot C, Billard P, Klebensberger J. Rare Earth Element (REE)-Dependent Growth of Pseudomonas putida KT2440 Relies on the ABC-Transporter PedA1A2BC and Is Influenced by Iron Availability. Front Microbiol 2019; 10:2494. [PMID: 31736923 PMCID: PMC6839425 DOI: 10.3389/fmicb.2019.02494] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 10/16/2019] [Indexed: 01/09/2023] Open
Abstract
In the soil-dwelling organism Pseudomonas putida KT2440, the rare earth element (REE)-utilizing, and pyrroloquinoline quinone (PQQ)-dependent ethanol dehydrogenase PedH is part of a periplasmic oxidation system that is vital for growth on various alcoholic volatiles. Production of PedH and its Ca2+-dependent counterpart PedE is inversely regulated in response to lanthanide (Ln3+) bioavailability, a mechanism termed the REE-switch. In the present study, we demonstrate that copper, zinc, and in particular, iron availability influences this regulation in a pyoverdine-independent manner by increasing the minimal Ln3+ concentration required for the REE-switch to occur by several orders of magnitude. A combined genetic and physiological approach reveals that an ABC-type transporter system encoded by the gene cluster pedA1A2BC is essential for efficient growth on 2-phenylethanol with low (nanomolar) Ln3+ concentrations. In the absence of pedA1A2BC, a ∼100-fold higher La3+-concentration is needed for PedH-dependent growth but not for the ability to repress growth based on PedE activity. From these results, we conclude that cytoplasmic uptake of lanthanides through PedA1A2BC is essential to facilitate REE-dependent growth on 2-phenylethanol under environmental conditions with poor REE bioavailability. Our data further suggest that the La3+/Fe2+/3+ ratio impacts the REE-switch through the mismetallation of putative La3+-binding proteins, such as the sensor histidine kinase PedS2, in the presence of high iron concentrations. As such, this study provides an example for the complexity of bacteria-metal interactions and highlights the importance of medium compositions when studying physiological traits in vitro in particular in regard to REE-dependent phenomena.
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Affiliation(s)
- Matthias Wehrmann
- Department of Technical Biochemistry, Institute of Biochemistry and Technical Biochemistry, University of Stuttgart, Stuttgart, Germany
| | - Charlotte Berthelot
- LIEC UMR7360, Faculté des Sciences et Technologies, Université de Lorraine, Vandoeuvre-lès-Nancy, France
- CNRS, LIEC UMR7360, Faculté des Sciences et Technologies, Vandoeuvre-lès-Nancy, France
| | - Patrick Billard
- LIEC UMR7360, Faculté des Sciences et Technologies, Université de Lorraine, Vandoeuvre-lès-Nancy, France
- CNRS, LIEC UMR7360, Faculté des Sciences et Technologies, Vandoeuvre-lès-Nancy, France
| | - Janosch Klebensberger
- Department of Technical Biochemistry, Institute of Biochemistry and Technical Biochemistry, University of Stuttgart, Stuttgart, Germany
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Reddy KR, Rai RK, Green SJ, Chetri JK. Effect of temperature on methane oxidation and community composition in landfill cover soil. J Ind Microbiol Biotechnol 2019; 46:1283-1295. [PMID: 31317292 DOI: 10.1061/(asce)ee.1943-7870.0001712] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 07/11/2019] [Indexed: 05/26/2023]
Abstract
Municipal solid waste (MSW) landfills are the third largest anthropogenic source of methane (CH4) emissions in the United States. The majority of CH4 generated in landfills is converted to carbon dioxide (CO2) by CH4-oxidizing bacteria (MOB) present in the landfill cover soil, whose activity is controlled by various environmental factors including temperature. As landfill temperature can fluctuate substantially seasonally, rates of CH4 oxidation can also vary, and this could lead to incomplete oxidation. This study aims at analyzing the effect of temperature on CH4 oxidation potential and microbial community structure of methanotrophs in laboratory-based studies of landfill cover soil and cultivated consortia. Soil and enrichment cultures were incubated at temperatures ranging from 6 to 70 °C, and rates of CH4 oxidation were measured, and the microbial community structure was analyzed using 16S rRNA gene amplicon sequencing and shotgun metagenome sequencing. CH4 oxidation occurred at temperatures from 6 to 50 °C in soil microcosm tests, and 6-40 °C in enrichment culture batch tests; maximum rates of oxidation were obtained at 30 °C. A corresponding shift in the soil microbiota was observed, with a transition from putative psychrophilic to thermophilic methanotrophs with increasing incubation temperature. A strong shift in methanotrophic community structure was observed above 30 °C. At temperatures up to 30 °C, methanotrophs from the genus Methylobacter were dominant in soils and enrichment cultures; at a temperature of 40 °C, putative thermophilic methanotrophs from the genus Methylocaldum become dominant. Maximum rate measurements of nearly 195 μg CH4 g-1 day-1 were observed in soil incubations, while observed maximum rates in enrichments were significantly lower, likely as a result of diffusion limitations. This study demonstrates that temperature is a critical factor affecting rates of landfill soil CH4 oxidation in vitro and that changing rates of CH4 oxidation are in part driven by changes in methylotroph community structure.
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Affiliation(s)
- Krishna R Reddy
- Department of Civil and Materials Engineering, University of Illinois at Chicago, 842 West Taylor Street, Chicago, IL, 60607, USA.
| | - Raksha K Rai
- Department of Civil and Materials Engineering, University of Illinois at Chicago, 842 West Taylor Street, Chicago, IL, 60607, USA
| | - Stefan J Green
- Department of Biological Sciences, Sequencing Core, Resources Center, University of Illinois at Chicago, 835 S. Wolcott, Chicago, IL, 60612, USA
| | - Jyoti K Chetri
- Department of Civil and Materials Engineering, University of Illinois at Chicago, 842 West Taylor Street, Chicago, IL, 60607, USA
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Houghton KM, Carere CR, Stott MB, McDonald IR. Thermophilic methanotrophs: in hot pursuit. FEMS Microbiol Ecol 2019; 95:5543213. [DOI: 10.1093/femsec/fiz125] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 07/31/2019] [Indexed: 11/13/2022] Open
Abstract
ABSTRACTMethane is a potent greenhouse gas responsible for 20–30% of global climate change effects. The global methane budget is ∼500–600 Tg y−1, with the majority of methane produced via microbial processes, including anthropogenic-mediated sources such as ruminant animals, rice fields, sewage treatment facilities and landfills. It is estimated that microbially mediated methane oxidation (methanotrophy) consumes >50% of global methane flux each year. Methanotrophy research has primarily focused on mesophilic methanotrophic representatives and cooler environments such as freshwater, wetlands or marine habitats from which they are sourced. Nevertheless, geothermal emissions of geological methane, produced from magma and lithosphere degassing micro-seepages, mud volcanoes and other geological sources, contribute an estimated 33–75 Tg y−1 to the global methane budget. The aim of this review is to summarise current literature pertaining to the activity of thermophilic and thermotolerant methanotrophs, both proteobacterial (Methylocaldum, Methylococcus, Methylothermus) and verrucomicrobial (Methylacidiphilum). We assert, on the basis of recently reported molecular and geochemical data, that geothermal ecosystems host hitherto unidentified species capable of methane oxidation at higher temperatures.
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Affiliation(s)
- Karen M Houghton
- GNS Science, Wairakei Research Centre, 114 Karetoto Rd, Taupō 3384, New Zealand
- School of Science, University of Waikato, Knighton Rd, Hamilton 3240, New Zealand
| | - Carlo R Carere
- GNS Science, Wairakei Research Centre, 114 Karetoto Rd, Taupō 3384, New Zealand
- Department of Chemical and Process Engineering, University of Canterbury, 20 Kirkwood Ave, Upper Riccarton, Christchurch 8041, New Zealand
| | - Matthew B Stott
- GNS Science, Wairakei Research Centre, 114 Karetoto Rd, Taupō 3384, New Zealand
- School of Biological Sciences, University of Canterbury, 20 Kirkwood Ave, Upper Riccarton, Christchurch 8041, New Zealand
| | - Ian R McDonald
- School of Science, University of Waikato, Knighton Rd, Hamilton 3240, New Zealand
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Nguyen AD, Kim D, Lee EY. A comparative transcriptome analysis of the novel obligate methanotroph Methylomonas sp. DH-1 reveals key differences in transcriptional responses in C1 and secondary metabolite pathways during growth on methane and methanol. BMC Genomics 2019; 20:130. [PMID: 30755173 PMCID: PMC6373157 DOI: 10.1186/s12864-019-5487-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 01/28/2019] [Indexed: 12/21/2022] Open
Abstract
Background Methanotrophs play an important role in biotechnological applications, with their ability to utilize single carbon (C1) feedstock such as methane and methanol to produce a range of high-value compounds. A newly isolated obligate methanotroph strain, Methylomonas sp. DH-1, became a platform strain for biotechnological applications because it has proven capable of producing chemicals, fuels, and secondary metabolites from methane and methanol. In this study, transcriptome analysis with RNA-seq was used to investigate the transcriptional change of Methylomonas sp. DH-1 on methane and methanol. This was done to improve knowledge about C1 assimilation and secondary metabolite pathways in this promising, but under-characterized, methane-bioconversion strain. Results We integrated genomic and transcriptomic analysis of the newly isolated Methylomonas sp. DH-1 grown on methane and methanol. Detailed transcriptomic analysis indicated that (i) Methylomonas sp. DH-1 possesses the ribulose monophosphate (RuMP) cycle and the Embden–Meyerhof–Parnas (EMP) pathway, which can serve as main pathways for C1 assimilation, (ii) the existence and the expression of a complete serine cycle and a complete tricarboxylic acid (TCA) cycle might contribute to methane conversion and energy production, and (iii) the highly active endogenous plasmid pDH1 may code for essential metabolic processes. Comparative transcriptomic analysis on methane and methanol as a sole carbon source revealed different transcriptional responses of Methylomonas sp. DH-1, especially in C1 assimilation, secondary metabolite pathways, and oxidative stress. Especially, these results suggest a shift of central metabolism when substrate changed from methane to methanol in which formaldehyde oxidation pathway and serine cycle carried more flux to produce acetyl-coA and NADH. Meanwhile, downregulation of TCA cycle when grown on methanol may suggest a shift of its main function is to provide de novo biosynthesis, but not produce NADH. Conclusions This study provides insights into the transcriptomic profile of Methylomonas sp. DH-1 grown on major carbon sources for C1 assimilation, providing in-depth knowledge on the metabolic pathways of this strain. These observations and analyses can contribute to future metabolic engineering with the newly isolated, yet under-characterized, Methylomonas sp. DH-1 to enhance its biochemical application in relevant industries. Electronic supplementary material The online version of this article (10.1186/s12864-019-5487-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Anh Duc Nguyen
- Department of Chemical Engineering, Kyung Hee University, Yongin, 17104, Republic of Korea
| | - Donghyuk Kim
- School of Energy and Chemical Engineering & School of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea.
| | - Eun Yeol Lee
- Department of Chemical Engineering, Kyung Hee University, Yongin, 17104, Republic of Korea.
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Orata FD, Meier-Kolthoff JP, Sauvageau D, Stein LY. Phylogenomic Analysis of the Gammaproteobacterial Methanotrophs (Order Methylococcales) Calls for the Reclassification of Members at the Genus and Species Levels. Front Microbiol 2018; 9:3162. [PMID: 30631317 PMCID: PMC6315193 DOI: 10.3389/fmicb.2018.03162] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 12/06/2018] [Indexed: 11/13/2022] Open
Abstract
The order Methylococcales constitutes the methanotrophs – bacteria that can metabolize methane, a potent greenhouse gas, as their sole source of energy. These bacteria are significant players in the global carbon cycle and can produce value-added products from methane, such as biopolymers, biofuels, and single-cell proteins for animal feed, among others. Previous studies using single-gene phylogenies have shown inconsistencies in the currently established taxonomic structure of this group. This study aimed to determine and resolve these issues by using whole-genome sequence analyses. Phylogenomic analysis and the use of similarity indexes for genomic comparisons – average amino acid identity, digital DNA–DNA hybridization (dDDH), and average nucleotide identity (ANI) – were performed on 91 Methylococcales genomes. Results suggest the reclassification of members at the genus and species levels. Firstly, to resolve polyphyly of the genus Methylomicrobium, Methylomicrobium alcaliphilum, “Methylomicrobium buryatense,” Methylomicrobium japanense, Methylomicrobium kenyense, and Methylomicrobium pelagicum are reclassified to a newly proposed genus, Methylotuvimicrobium gen. nov.; they are therefore renamed to Methylotuvimicrobium alcaliphilum comb. nov., “Methylotuvimicrobium buryatense” comb. nov., Methylotuvimicrobium japanense comb. nov., Methylotuvimicrobium kenyense comb. nov., and Methylotuvimicrobium pelagicum comb. nov., respectively. Secondly, due to the phylogenetic affinity and phenotypic similarities of Methylosarcina lacus with Methylomicrobium agile and Methylomicrobium album, the reclassification of the former species to Methylomicrobium lacus comb. nov. is proposed. Thirdly, using established same-species delineation thresholds (70% dDDH and 95% ANI), Methylobacter whittenburyi is proposed to be a later heterotypic synonym of Methylobacter marinus (89% dDDH and 99% ANI). Also, the effectively but not validly published “Methylomonas denitrificans” was identified as Methylomonas methanica (92% dDDH and 100% ANI), indicating that the former is a later heterotypic synonym of the latter. Lastly, strains MC09, R-45363, and R-45371, currently identified as M. methanica, each represent a putative novel species of the genus Methylomonas (21–35% dDDH and 74–88% ANI against M. methanica) and were reclassified as Methylomonas sp. strains. It is imperative to resolve taxonomic inconsistencies within this group, first and foremost, to avoid confusion with ecological and evolutionary interpretations in subsequent studies.
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Affiliation(s)
- Fabini D Orata
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada.,Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Jan P Meier-Kolthoff
- Department of Microorganisms, Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Dominic Sauvageau
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada
| | - Lisa Y Stein
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
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Ren J, Na D, Yoo SM. Optimization of chemico-physical transformation methods for various bacterial species using diverse chemical compounds and nanomaterials. J Biotechnol 2018; 288:55-60. [DOI: 10.1016/j.jbiotec.2018.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 10/31/2018] [Accepted: 11/04/2018] [Indexed: 01/13/2023]
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Bioconversion of methane to C-4 carboxylic acids using carbon flux through acetyl-CoA in engineered Methylomicrobium buryatense 5GB1C. Metab Eng 2018; 48:175-183. [PMID: 29883803 DOI: 10.1016/j.ymben.2018.06.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 05/31/2018] [Accepted: 06/01/2018] [Indexed: 11/24/2022]
Abstract
Methane, the primary component of natural gas, is the second most abundant greenhouse gas (GHG) and contributes significantly to climate change. The conversion of methane to industrial platform chemicals provides an attractive opportunity to decrease GHG emissions and utilize this inexpensive and abundantly available gas as a carbon feedstock. While technologies exist for chemical conversion of methane to liquid fuels, the technical complexity of these processes mandate high capital expenditure, large-scale commercial facilities to leverage economies of scale that cannot be efficiently scaled down. Alternatively, bioconversion technologies capable of efficient small-scale operation with high carbon and energy efficiency can enable deployment at remote methane resources inaccessible to current chemical technologies. Aerobic obligate methanotrophs, specifically Methylomicrobium buryatense 5GB1, have recently garnered increased research interest for development of such bio-technologies. In this study, we demonstrate production of C-4 carboxylic acids non-native to the host, specifically crotonic and butyric acids, from methane in an engineered M. buryatense 5GB1C by diversion of carbon flux through the acetyl-CoA node of central 'sugar' linked metabolic pathways using reverse β-oxidation pathway genes. The synthesis of short chain carboxylic acids through the acetyl-CoA node demonstrates the potential for engineering M. buryatense 5GB1 as a platform for bioconversion of methane to a number of value added industrial chemicals, and presents new opportunities for further diversifying the products obtainable from methane as the feedstock.
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31
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Ro SY, Ross MO, Deng YW, Batelu S, Lawton TJ, Hurley JD, Stemmler TL, Hoffman BM, Rosenzweig AC. From micelles to bicelles: Effect of the membrane on particulate methane monooxygenase activity. J Biol Chem 2018; 293:10457-10465. [PMID: 29739854 DOI: 10.1074/jbc.ra118.003348] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 05/06/2018] [Indexed: 11/06/2022] Open
Abstract
Particulate methane monooxygenase (pMMO) is a copper-dependent integral membrane metalloenzyme that converts methane to methanol in methanotrophic bacteria. Studies of isolated pMMO have been hindered by loss of enzymatic activity upon its removal from the native membrane. To characterize pMMO in a membrane-like environment, we reconstituted pMMOs from Methylococcus (Mcc.) capsulatus (Bath) and Methylomicrobium (Mm.) alcaliphilum 20Z into bicelles. Reconstitution into bicelles recovers methane oxidation activity lost upon detergent solubilization and purification without substantial alterations to copper content or copper electronic structure, as observed by electron paramagnetic resonance (EPR) spectroscopy. These findings suggest that loss of pMMO activity upon isolation is due to removal from the membranes rather than caused by loss of the catalytic copper ions. A 2.7 Å resolution crystal structure of pMMO from Mm. alcaliphilum 20Z reveals a mononuclear copper center in the PmoB subunit and indicates that the transmembrane PmoC subunit may be conformationally flexible. Finally, results from extended X-ray absorption fine structure (EXAFS) analysis of pMMO from Mm. alcaliphilum 20Z were consistent with the observed monocopper center in the PmoB subunit. These results underscore the importance of studying membrane proteins in a membrane-like environment and provide valuable insight into pMMO function.
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Affiliation(s)
- Soo Y Ro
- From the Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, Illinois 60208 and
| | - Matthew O Ross
- From the Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, Illinois 60208 and
| | - Yue Wen Deng
- From the Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, Illinois 60208 and
| | - Sharon Batelu
- the Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan 48201
| | - Thomas J Lawton
- From the Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, Illinois 60208 and
| | - Joseph D Hurley
- From the Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, Illinois 60208 and
| | - Timothy L Stemmler
- the Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan 48201
| | - Brian M Hoffman
- From the Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, Illinois 60208 and
| | - Amy C Rosenzweig
- From the Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, Illinois 60208 and
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Fei Q, Puri AW, Smith H, Dowe N, Pienkos PT. Enhanced biological fixation of methane for microbial lipid production by recombinant Methylomicrobium buryatense. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:129. [PMID: 29755588 PMCID: PMC5934843 DOI: 10.1186/s13068-018-1128-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 04/23/2018] [Indexed: 05/24/2023]
Abstract
BACKGROUND Due to the success of shale gas development in the US, the production cost of natural gas has been reduced significantly, which in turn has made methane (CH4), the major component of natural gas, a potential alternative substrate for bioconversion processes compared with other high-price raw material sources or edible feedstocks. Therefore, exploring effective ways to use CH4 for the production of biofuels is attractive. Biological fixation of CH4 by methanotrophic bacteria capable of using CH4 as their sole carbon and energy source has obtained great attention for biofuel production from this resource. RESULTS In this study, a fast-growing and lipid-rich methanotroph, Methylomicrobium buryatense 5GB1 and its glycogen-knock-out mutant (AP18) were investigated for the production of lipids derived from intracellular membranes, which are key precursors for the production of green diesel. The effects of culture conditions on cell growth and lipid production were investigated in high cell density cultivation with continuous feeding of CH4 and O2. The highest dry cell weight observed was 21.4 g/L and the maximum lipid productivity observed was 45.4 mg/L/h obtained in batch cultures, which corresponds to a 2-fold enhancement in cell density and 3-fold improvement in lipid production, compared with previous reported data from cultures of 5GB1. A 90% enhancement of lipid content was achieved by limiting the biosynthesis of glycogen in strain AP18. Increased CH4/O2 uptake and CO2 evaluation rates were observed in AP18 cultures suggesting that more carbon substrate and energy are needed for AP18 growth while producing lipids. The lipid produced by M. buryatense was estimated to have a cetane number of 75, which is 50% higher than biofuel standards requested by US and EU. CONCLUSIONS Cell growth and lipid production were significantly influenced by culture conditions for both 5GB1 and AP18. Enhanced lipid production in terms of titer, productivity, and content was achieved under high cell density culture conditions by blocking glycogen accumulation as a carbon sink in the strain AP18. Differences observed in CH4/O2 gas uptake and CO2 evolution rates as well as cell growth and glycogen accumulation between 5GB1 and AP18 suggest changes in the metabolic network between these strains. This bioconversion process provides a promising opportunity to transform CH4 into biofuel molecules and encourages further investigation to elucidate the remarkable CH4 biofixation mechanism used by these bacteria.
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Affiliation(s)
- Qiang Fei
- School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an, China
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO USA
| | - Aaron W. Puri
- Department of Chemical Engineering, University of Washington, Seattle, WA USA
| | - Holly Smith
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO USA
| | - Nancy Dowe
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO USA
| | - Philip. T. Pienkos
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO USA
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Garg S, Clomburg JM, Gonzalez R. A modular approach for high-flux lactic acid production from methane in an industrial medium using engineered Methylomicrobium buryatense 5GB1. J Ind Microbiol Biotechnol 2018; 45:379-391. [PMID: 29675615 DOI: 10.1007/s10295-018-2035-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 04/03/2018] [Indexed: 12/01/2022]
Abstract
Convergence of market drivers such as abundant availability of inexpensive natural gas and increasing awareness of its global warming effects have created new opportunities for the development of small-scale gas-to-liquid (GTL) conversion technologies that can efficiently utilize methane, the primary component of natural gas. Leveraging the unique ability of methanotrophs that use methane as carbon and energy source, biological GTL platforms can be envisioned that are readily deployable at remote petroleum drilling sites where large chemical GTL infrastructure is uneconomical to set-up. Methylomicrobium buryatense, an obligate methanotroph, has gained traction as a potential industrial methanotrophic host because of availability of genetic tools and recent advances in its metabolic engineering. However, progress is impeded by low strain performance and lack of an industrial medium. In this study, we first established a small-scale cultivation platform using Hungate tubes for growth of M. buryatense at medium-to-high-throughput that also enabled 2X faster growth compared to that obtained in traditional glass serum bottles. Then, employing a synthetic biology approach we engineered M. buryatense with varying promoter (inducible and constitutive) and ribosome-binding site combinations, and obtained a strain capable of producing L-lactate from methane at a flux 14-fold higher than previously reported. Finally, we demonstrated L-lactate production in an industrial medium by replacing nitrate with less-expensive ammonium as the nitrogen source. Under these conditions, L-lactate was synthesized at a flux approximately 50-fold higher than that reported previously in a bioreactor system while achieving a titer of 0.6 g/L. These findings position M. buryatense closer to becoming an industrial host strain of choice, and pave new avenues for accelerating methane-to-chemical conversion using synthetic biology.
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Affiliation(s)
- Shivani Garg
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street MS-667, Houston, TX, 77005, USA
| | - James M Clomburg
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street MS-667, Houston, TX, 77005, USA
| | - Ramon Gonzalez
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street MS-667, Houston, TX, 77005, USA. .,Department of Bioengineering, Rice University, Houston, 77005, USA.
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Abstract
Aerobic methanotrophs have long been known to play a critical role in the global carbon cycle, being capable of converting methane to biomass and carbon dioxide. Interestingly, these microbes exhibit great sensitivity to copper and rare-earth elements, with the expression of key genes involved in the central pathway of methane oxidation controlled by the availability of these metals. That is, these microbes have a "copper switch" that controls the expression of alternative methane monooxygenases and a "rare-earth element switch" that controls the expression of alternative methanol dehydrogenases. Further, it has been recently shown that some methanotrophs can detoxify inorganic mercury and demethylate methylmercury; this finding is remarkable, as the canonical organomercurial lyase does not exist in these methanotrophs, indicating that a novel mechanism is involved in methylmercury demethylation. Here, we review recent findings on methanotrophic interactions with metals, with a particular focus on these metal switches and the mechanisms used by methanotrophs to bind and sequester metals.
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Collins DA, Kalyuzhnaya MG. Navigating methane metabolism: Enzymes, compartments, and networks. Methods Enzymol 2018; 613:349-383. [DOI: 10.1016/bs.mie.2018.10.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Gilman A, Fu Y, Hendershott M, Chu F, Puri AW, Smith AL, Pesesky M, Lieberman R, Beck DAC, Lidstrom ME. Oxygen-limited metabolism in the methanotroph Methylomicrobium buryatense 5GB1C. PeerJ 2017; 5:e3945. [PMID: 29062611 PMCID: PMC5652258 DOI: 10.7717/peerj.3945] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 09/30/2017] [Indexed: 11/20/2022] Open
Abstract
The bacteria that grow on methane aerobically (methanotrophs) support populations of non-methanotrophs in the natural environment by excreting methane-derived carbon. One group of excreted compounds are short-chain organic acids, generated in highest abundance when cultures are grown under O2-starvation. We examined this O2-starvation condition in the methanotroph Methylomicrobium buryatense 5GB1. The M. buryatense 5GB1 genome contains homologs for all enzymes necessary for a fermentative metabolism, and we hypothesize that a metabolic switch to fermentation can be induced by low-O2 conditions. Under prolonged O2-starvation in a closed vial, this methanotroph increases the amount of acetate excreted about 10-fold, but the formate, lactate, and succinate excreted do not respond to this culture condition. In bioreactor cultures, the amount of each excreted product is similar across a range of growth rates and limiting substrates, including O2-limitation. A set of mutants were generated in genes predicted to be involved in generating or regulating excretion of these compounds and tested for growth defects, and changes in excretion products. The phenotypes and associated metabolic flux modeling suggested that in M. buryatense 5GB1, formate and acetate are excreted in response to redox imbalance. Our results indicate that even under O2-starvation conditions, M. buryatense 5GB1 maintains a metabolic state representing a combination of fermentation and respiration metabolism.
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Affiliation(s)
- Alexey Gilman
- Department of Chemical Engineering, University of Washington, Seattle, WA, United States of America
| | - Yanfen Fu
- Department of Chemical Engineering, University of Washington, Seattle, WA, United States of America
| | | | | | - Aaron W Puri
- Department of Chemical Engineering, University of Washington, Seattle, WA, United States of America
| | | | - Mitchell Pesesky
- Department of Chemical Engineering, University of Washington, Seattle, WA, United States of America
| | - Rose Lieberman
- Department of Biology, George Washington University, Washington, D.C., USA
| | - David A C Beck
- Department of Chemical Engineering, University of Washington, Seattle, WA, United States of America.,eScience Institute, University of Washington, Seattle, WA, USA
| | - Mary E Lidstrom
- Department of Chemical Engineering, University of Washington, Seattle, WA, United States of America.,Department of Microbiology, University of Washington, Seattle, WA, USA
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The oxidative TCA cycle operates during methanotrophic growth of the Type I methanotroph Methylomicrobium buryatense 5GB1. Metab Eng 2017; 42:43-51. [DOI: 10.1016/j.ymben.2017.05.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 05/19/2017] [Accepted: 05/20/2017] [Indexed: 11/18/2022]
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Demidenko A, Akberdin IR, Allemann M, Allen EE, Kalyuzhnaya MG. Fatty Acid Biosynthesis Pathways in Methylomicrobium buryatense 5G(B1). Front Microbiol 2017; 7:2167. [PMID: 28119683 PMCID: PMC5222806 DOI: 10.3389/fmicb.2016.02167] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 12/23/2016] [Indexed: 01/02/2023] Open
Abstract
Methane utilization by methanotrophic bacteria is an attractive application for biotechnological conversion of natural or biogas into high-added-value products. Haloalcaliphilic methanotrophic bacteria belonging to the genus Methylomicrobium are among the most promising strains for methane-based biotechnology, providing easy and inexpensive cultivation, rapid growth, and the availability of established genetic tools. A number of methane bioconversions using these microbial cultures have been discussed, including the derivation of biodiesel, alkanes, and OMEGA-3 supplements. These compounds are derived from bacterial fatty acid pools. Here, we investigate fatty acid biosynthesis in Methylomicrobium buryatense 5G(B1). Most of the genes homologous to typical Type II fatty acid biosynthesis pathways could be annotated by bioinformatics analyses, with the exception of fatty acid transport and regulatory elements. Different approaches for improving fatty acid accumulation were investigated. These studies indicated that both fatty acid degradation and acetyl- and malonyl-CoA levels are bottlenecks for higher level fatty acid production. The best strain generated in this study synthesizes 111 ± 2 mg/gDCW of extractable fatty acids, which is ~20% more than the original strain. A candidate gene for fatty acid biosynthesis regulation, farE, was identified and studied. Its deletion resulted in drastic changes to the fatty acid profile, leading to an increased pool of C18-fatty acid methyl ester. The FarE-regulon was further investigated by RNA-seq analysis of gene expression in farE-knockout mutants and farE-overexpressing strains. These gene profiles highlighted a novel set of enzymes and regulators involved in fatty acid biosynthesis. The gene expression and fatty acid profiles of the different farE-strains support the hypothesis that metabolic fluxes upstream of fatty acid biosynthesis restrict fatty acid production in the methanotroph.
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Affiliation(s)
- Aleksandr Demidenko
- Department of Biology, San Diego State University, Campanile DriveSan Diego, CA, USA; Scripps Institution of Oceanography, University of California San Diego, Gilman DriveLa Jolla, CA, USA
| | - Ilya R Akberdin
- Department of Biology, San Diego State University, Campanile Drive San Diego, CA, USA
| | - Marco Allemann
- Scripps Institution of Oceanography, University of California San Diego, Gilman Drive La Jolla, CA, USA
| | - Eric E Allen
- Scripps Institution of Oceanography, University of California San Diego, Gilman Drive La Jolla, CA, USA
| | - Marina G Kalyuzhnaya
- Department of Biology, San Diego State University, Campanile Drive San Diego, CA, USA
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Clomburg JM, Crumbley AM, Gonzalez R. Industrial biomanufacturing: The future of chemical production. Science 2017; 355:355/6320/aag0804. [DOI: 10.1126/science.aag0804] [Citation(s) in RCA: 271] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 10/21/2016] [Indexed: 12/18/2022]
Abstract
The current model for industrial chemical manufacturing employs large-scale megafacilities that benefit from economies of unit scale. However, this strategy faces environmental, geographical, political, and economic challenges associated with energy and manufacturing demands. We review how exploiting biological processes for manufacturing (i.e., industrial biomanufacturing) addresses these concerns while also supporting and benefiting from economies of unit number. Key to this approach is the inherent small scale and capital efficiency of bioprocesses and the ability of engineered biocatalysts to produce designer products at high carbon and energy efficiency with adjustable output, at high selectivity, and under mild process conditions. The biological conversion of single-carbon compounds represents a test bed to establish this paradigm, enabling rapid, mobile, and widespread deployment, access to remote and distributed resources, and adaptation to new and changing markets.
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Deng Y, Liu Y, Dumont M, Conrad R. Salinity Affects the Composition of the Aerobic Methanotroph Community in Alkaline Lake Sediments from the Tibetan Plateau. MICROBIAL ECOLOGY 2017; 73:101-110. [PMID: 27878346 DOI: 10.1007/s00248-016-0879-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 10/12/2016] [Indexed: 06/06/2023]
Abstract
Lakes are widely distributed on the Tibetan Plateau, which plays an important role in natural methane emission. Aerobic methanotrophs in lake sediments reduce the amount of methane released into the atmosphere. However, no study to date has analyzed the methanotroph community composition and their driving factors in sediments of these high-altitude lakes (>4000 m). To provide new insights on this aspect, the abundance and composition in the sediments of six high-altitude alkaline lakes (including both freshwater and saline lakes) on the Tibetan Plateau were studied. The quantitative PCR, terminal restriction fragment length polymorphism, and 454-pyrosequencing methods were used to target the pmoA genes. The pmoA gene copies ranged 104-106 per gram fresh sediment. Type I methanotrophs predominated in Tibetan lake sediments, with Methylobacter and uncultivated type Ib methanotrophs being dominant in freshwater lakes and Methylomicrobium in saline lakes. Combining the pmoA-pyrosequencing data from Tibetan lakes with other published pmoA-sequencing data from lake sediments of other regions, a significant salinity and alkalinity effect (P = 0.001) was detected, especially salinity, which explained ∼25% of methanotroph community variability. The main effect was Methylomicrobium being dominant (up to 100%) in saline lakes only. In freshwater lakes, however, methanotroph composition was relatively diverse, including Methylobacter, Methylocystis, and uncultured type Ib clusters. This study provides the first methanotroph data for high-altitude lake sediments (>4000 m) and shows that salinity is a driving factor for the community composition of aerobic methanotrophs.
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Affiliation(s)
- Yongcui Deng
- College of Geographic Sciences, Nanjing Normal University, 1 Wenyuan Road, 210023, Nanjing, China
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Straße 10, 35043, Marburg, Germany
- Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, 1 Wenyuan Road, 210023, Nanjing, China
| | - Yongqin Liu
- Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, 100085, Beijing, China.
| | - Marc Dumont
- Biological Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - Ralf Conrad
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Straße 10, 35043, Marburg, Germany
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41
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Cantera S, Lebrero R, Sadornil L, García-Encina PA, Muñoz R. Valorization of CH4 emissions into high-added-value products: Assessing the production of ectoine coupled with CH4 abatement. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2016; 182:160-165. [PMID: 27472052 DOI: 10.1016/j.jenvman.2016.07.064] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 07/17/2016] [Accepted: 07/18/2016] [Indexed: 06/06/2023]
Abstract
This study assessed an innovative strategy for the valorization of dilute methane emissions based on the bio-conversion of CH4 (the second most important greenhouse gas (GHG)) into ectoine by the methanotrophic ectoine-producing strain Methylomicrobium alcaliphilum 20 Z. The influence of CH4 (2-20%), Cu(2+) (0.05-50 μM) and NaCl (0-9%) concentration as well as temperature (25-35 °C) on ectoine synthesis and specific CH4 biodegradation rate was evaluated for the first time. Concentrations of 20% CH4 (at 3% NaCl, 0.05 μM Cu(2+), 25 °C) and 6% NaCl (at 4% CH4, 0.05 μM Cu(2+), 25 °C) supported the maximum intra-cellular ectoine production yield (31.0 ±1.7 and 66.9 ±4.2 mg g biomass(-1), respectively). On the other hand, extra-cellular ectoine concentrations of up to 4.7 ± 0.1 mg L(-1) were detected at high Cu(2+)concentrations (50 μM), despite this methanotroph has not been previously classified as an ectoine-excreting strain. This research demonstrated the feasibility of the bio-conversion of dilute emissions of methane into high-added value products in an attempt to develop a sustainable GHG bioeconomy.
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Affiliation(s)
- Sara Cantera
- Department of Chemical Engineering and Environmental Technology, Valladolid University, Dr. Mergelina, s/n, Valladolid, Spain
| | - Raquel Lebrero
- Department of Chemical Engineering and Environmental Technology, Valladolid University, Dr. Mergelina, s/n, Valladolid, Spain
| | - Lidia Sadornil
- Department of Chemical Engineering and Environmental Technology, Valladolid University, Dr. Mergelina, s/n, Valladolid, Spain
| | - Pedro A García-Encina
- Department of Chemical Engineering and Environmental Technology, Valladolid University, Dr. Mergelina, s/n, Valladolid, Spain
| | - Raúl Muñoz
- Department of Chemical Engineering and Environmental Technology, Valladolid University, Dr. Mergelina, s/n, Valladolid, Spain.
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Wei JH, Yin X, Welander PV. Sterol Synthesis in Diverse Bacteria. Front Microbiol 2016; 7:990. [PMID: 27446030 PMCID: PMC4919349 DOI: 10.3389/fmicb.2016.00990] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 06/09/2016] [Indexed: 11/13/2022] Open
Abstract
Sterols are essential components of eukaryotic cells whose biosynthesis and function has been studied extensively. Sterols are also recognized as the diagenetic precursors of steranes preserved in sedimentary rocks where they can function as geological proxies for eukaryotic organisms and/or aerobic metabolisms and environments. However, production of these lipids is not restricted to the eukaryotic domain as a few bacterial species also synthesize sterols. Phylogenomic studies have identified genes encoding homologs of sterol biosynthesis proteins in the genomes of several additional species, indicating that sterol production may be more widespread in the bacterial domain than previously thought. Although the occurrence of sterol synthesis genes in a genome indicates the potential for sterol production, it provides neither conclusive evidence of sterol synthesis nor information about the composition and abundance of basic and modified sterols that are actually being produced. Here, we coupled bioinformatics with lipid analyses to investigate the scope of bacterial sterol production. We identified oxidosqualene cyclase (Osc), which catalyzes the initial cyclization of oxidosqualene to the basic sterol structure, in 34 bacterial genomes from five phyla (Bacteroidetes, Cyanobacteria, Planctomycetes, Proteobacteria, and Verrucomicrobia) and in 176 metagenomes. Our data indicate that bacterial sterol synthesis likely occurs in diverse organisms and environments and also provides evidence that there are as yet uncultured groups of bacterial sterol producers. Phylogenetic analysis of bacterial and eukaryotic Osc sequences confirmed a complex evolutionary history of sterol synthesis in this domain. Finally, we characterized the lipids produced by Osc-containing bacteria and found that we could generally predict the ability to synthesize sterols. However, predicting the final modified sterol based on our current knowledge of sterol synthesis was difficult. Some bacteria produced demethylated and saturated sterol products even though they lacked homologs of the eukaryotic proteins required for these modifications emphasizing that several aspects of bacterial sterol synthesis are still completely unknown.
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Affiliation(s)
| | | | - Paula V. Welander
- Department of Earth System Science, Stanford UniversityStanford, CA, USA
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43
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Bioconversion of methane to lactate by an obligate methanotrophic bacterium. Sci Rep 2016; 6:21585. [PMID: 26902345 PMCID: PMC4763203 DOI: 10.1038/srep21585] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 01/25/2016] [Indexed: 01/21/2023] Open
Abstract
Methane is the second most abundant greenhouse gas (GHG), with nearly 60% of emissions derived from anthropogenic sources. Microbial conversion of methane to fuels and value-added chemicals offers a means to reduce GHG emissions, while also valorizing this otherwise squandered high-volume, high-energy gas. However, to date, advances in methane biocatalysis have been constrained by the low-productivity and limited genetic tractability of natural methane-consuming microbes. Here, leveraging recent identification of a novel, tractable methanotrophic bacterium, Methylomicrobium buryatense, we demonstrate microbial biocatalysis of methane to lactate, an industrial platform chemical. Heterologous overexpression of a Lactobacillus helveticus L-lactate dehydrogenase in M. buryatense resulted in an initial titer of 0.06 g lactate/L from methane. Cultivation in a 5 L continuously stirred tank bioreactor enabled production of 0.8 g lactate/L, representing a 13-fold improvement compared to the initial titer. The yields (0.05 g lactate/g methane) and productivity (0.008 g lactate/L/h) indicate the need and opportunity for future strain improvement. Additionally, real-time analysis of methane utilization implicated gas-to-liquid transfer and/or microbial methane consumption as process limitations. This work opens the door to develop an array of methanotrophic bacterial strain-engineering strategies currently employed for biocatalytic sugar upgrading to "green" chemicals and fuels.
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Sherry A, Osborne KA, Sidgwick FR, Gray ND, Talbot HM. A temperate river estuary is a sink for methanotrophs adapted to extremes of pH, temperature and salinity. ENVIRONMENTAL MICROBIOLOGY REPORTS 2016; 8:122-31. [PMID: 26617278 PMCID: PMC4959530 DOI: 10.1111/1758-2229.12359] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 11/19/2015] [Indexed: 05/08/2023]
Abstract
River Tyne (UK) estuarine sediments harbour a genetically and functionally diverse community of methane-oxidizing bacteria (methanotrophs), the composition and activity of which were directly influenced by imposed environmental conditions (pH, salinity, temperature) that extended far beyond those found in situ. In aerobic sediment slurries methane oxidation rates were monitored together with the diversity of a functional gene marker for methanotrophs (pmoA). Under near in situ conditions (4-30°C, pH 6-8, 1-15 g l(-1) NaCl), communities were enriched by sequences affiliated with Methylobacter and Methylomonas spp. and specifically a Methylobacter psychrophilus-related species at 4-21°C. More extreme conditions, namely high temperatures ≥ 40°C, high ≥ 9 and low ≤ 5 pH, and high salinities ≥ 35 g l(-1) selected for putative thermophiles (Methylocaldum), acidophiles (Methylosoma) and haloalkaliphiles (Methylomicrobium). The presence of these extreme methanotrophs (unlikely to be part of the active community in situ) indicates passive dispersal from surrounding environments into the estuary.
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Affiliation(s)
- Angela Sherry
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Kate A Osborne
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Frances R Sidgwick
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Neil D Gray
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Helen M Talbot
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
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Electroporation-Based Genetic Manipulation in Type I Methanotrophs. Appl Environ Microbiol 2016; 82:2062-2069. [PMID: 26801578 DOI: 10.1128/aem.03724-15] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Accepted: 01/19/2016] [Indexed: 01/26/2023] Open
Abstract
Methane is becoming a major candidate for a prominent carbon feedstock in the future, and the bioconversion of methane into valuable products has drawn increasing attention. To facilitate the use of methanotrophic organisms as industrial strains and accelerate our ability to metabolically engineer methanotrophs, simple and rapid genetic tools are needed. Electroporation is one such enabling tool, but to date it has not been successful in a group of methanotrophs of interest for the production of chemicals and fuels, the gammaproteobacterial (type I) methanotrophs. In this study, we developed electroporation techniques with a high transformation efficiency for three different type I methanotrophs: Methylomicrobium buryatense 5GB1C, Methylomonas sp. strain LW13, and Methylobacter tundripaludum 21/22. We further developed this technique in M. buryatense, a haloalkaliphilic aerobic methanotroph that demonstrates robust growth with a high carbon conversion efficiency and is well suited for industrial use for the bioconversion of methane. On the basis of the high transformation efficiency of M. buryatense, gene knockouts or integration of a foreign fragment into the chromosome can be easily achieved by direct electroporation of PCR-generated deletion or integration constructs. Moreover, site-specific recombination (FLP-FRT [FLP recombination target] recombination) and sacB counterselection systems were employed to perform marker-free manipulation, and two new antibiotics, zeocin and hygromycin, were validated to be antibiotic markers in this strain. Together, these tools facilitate the rapid genetic manipulation of M. buryatense and other type I methanotrophs, promoting the ability to perform fundamental research and industrial process development with these strains.
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Knief C. Diversity and Habitat Preferences of Cultivated and Uncultivated Aerobic Methanotrophic Bacteria Evaluated Based on pmoA as Molecular Marker. Front Microbiol 2015; 6:1346. [PMID: 26696968 PMCID: PMC4678205 DOI: 10.3389/fmicb.2015.01346] [Citation(s) in RCA: 256] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 11/16/2015] [Indexed: 01/06/2023] Open
Abstract
Methane-oxidizing bacteria are characterized by their capability to grow on methane as sole source of carbon and energy. Cultivation-dependent and -independent methods have revealed that this functional guild of bacteria comprises a substantial diversity of organisms. In particular the use of cultivation-independent methods targeting a subunit of the particulate methane monooxygenase (pmoA) as functional marker for the detection of aerobic methanotrophs has resulted in thousands of sequences representing "unknown methanotrophic bacteria." This limits data interpretation due to restricted information about these uncultured methanotrophs. A few groups of uncultivated methanotrophs are assumed to play important roles in methane oxidation in specific habitats, while the biology behind other sequence clusters remains still largely unknown. The discovery of evolutionary related monooxygenases in non-methanotrophic bacteria and of pmoA paralogs in methanotrophs requires that sequence clusters of uncultivated organisms have to be interpreted with care. This review article describes the present diversity of cultivated and uncultivated aerobic methanotrophic bacteria based on pmoA gene sequence diversity. It summarizes current knowledge about cultivated and major clusters of uncultivated methanotrophic bacteria and evaluates habitat specificity of these bacteria at different levels of taxonomic resolution. Habitat specificity exists for diverse lineages and at different taxonomic levels. Methanotrophic genera such as Methylocystis and Methylocaldum are identified as generalists, but they harbor habitat specific methanotrophs at species level. This finding implies that future studies should consider these diverging preferences at different taxonomic levels when analyzing methanotrophic communities.
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Affiliation(s)
- Claudia Knief
- Institute of Crop Science and Resource Conservation – Molecular Biology of the Rhizosphere, University of BonnBonn, Germany
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de la Torre A, Metivier A, Chu F, Laurens LML, Beck DAC, Pienkos PT, Lidstrom ME, Kalyuzhnaya MG. Genome-scale metabolic reconstructions and theoretical investigation of methane conversion in Methylomicrobium buryatense strain 5G(B1). Microb Cell Fact 2015; 14:188. [PMID: 26607880 PMCID: PMC4658805 DOI: 10.1186/s12934-015-0377-3] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 11/03/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Methane-utilizing bacteria (methanotrophs) are capable of growth on methane and are attractive systems for bio-catalysis. However, the application of natural methanotrophic strains to large-scale production of value-added chemicals/biofuels requires a number of physiological and genetic alterations. An accurate metabolic model coupled with flux balance analysis can provide a solid interpretative framework for experimental data analyses and integration. RESULTS A stoichiometric flux balance model of Methylomicrobium buryatense strain 5G(B1) was constructed and used for evaluating metabolic engineering strategies for biofuels and chemical production with a methanotrophic bacterium as the catalytic platform. The initial metabolic reconstruction was based on whole-genome predictions. Each metabolic step was manually verified, gapfilled, and modified in accordance with genome-wide expression data. The final model incorporates a total of 841 reactions (in 167 metabolic pathways). Of these, up to 400 reactions were recruited to produce 118 intracellular metabolites. The flux balance simulations suggest that only the transfer of electrons from methanol oxidation to methane oxidation steps can support measured growth and methane/oxygen consumption parameters, while the scenario employing NADH as a possible source of electrons for particulate methane monooxygenase cannot. Direct coupling between methane oxidation and methanol oxidation accounts for most of the membrane-associated methane monooxygenase activity. However the best fit to experimental results is achieved only after assuming that the efficiency of direct coupling depends on growth conditions and additional NADH input (about 0.1-0.2 mol of incremental NADH per one mol of methane oxidized). The additional input is proposed to cover loss of electrons through inefficiency and to sustain methane oxidation at perturbations or support uphill electron transfer. Finally, the model was used for testing the carbon conversion efficiency of different pathways for C1-utilization, including different variants of the ribulose monophosphate pathway and the serine cycle. CONCLUSION We demonstrate that the metabolic model can provide an effective tool for predicting metabolic parameters for different nutrients and genetic perturbations, and as such, should be valuable for metabolic engineering of the central metabolism of M. buryatense strains.
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Affiliation(s)
- Andrea de la Torre
- Biology Department, San Diego State University, North Life Science Room 406, San Diego, CA, 92182-4614, USA.
| | - Aisha Metivier
- Biology Department, San Diego State University, North Life Science Room 406, San Diego, CA, 92182-4614, USA.
| | - Frances Chu
- Department of Chemical Engineering, University of Washington, Seattle, USA.
| | - Lieve M L Laurens
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO, USA.
| | - David A C Beck
- Department of Chemical Engineering, University of Washington, Seattle, USA.
- eScience Institute, University of Washington, Seattle, USA.
| | - Philip T Pienkos
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO, USA.
| | - Mary E Lidstrom
- Department of Chemical Engineering, University of Washington, Seattle, USA.
- Department of Microbiology, University of Washington, Seattle, USA.
| | - Marina G Kalyuzhnaya
- Biology Department, San Diego State University, North Life Science Room 406, San Diego, CA, 92182-4614, USA.
- Viral Information Institute, San Diego State University, San Diego, USA.
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Gilman A, Laurens LM, Puri AW, Chu F, Pienkos PT, Lidstrom ME. Bioreactor performance parameters for an industrially-promising methanotroph Methylomicrobium buryatense 5GB1. Microb Cell Fact 2015; 14:182. [PMID: 26572866 PMCID: PMC4647623 DOI: 10.1186/s12934-015-0372-8] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 10/29/2015] [Indexed: 11/22/2022] Open
Abstract
Background Methane is a feedstock of interest for the future, both from natural gas and from renewable biogas sources. Methanotrophic bacteria have the potential to enable commercial methane bioconversion to value-added products such as fuels and chemicals. A strain of interest for such applications is Methylomicrobium buryatense 5GB1, due to its robust growth characteristics. However, to take advantage of the potential of this methanotroph, it is important to generate comprehensive bioreactor-based datasets for different growth conditions to compare bioprocess parameters. Results Datasets of growth parameters, gas utilization rates, and products (total biomass, extracted fatty acids, glycogen, excreted acids) were obtained for cultures of M. buryatense 5GB1 grown in continuous culture under methane limitation and O2 limitation conditions. Additionally, experiments were performed involving unrestricted batch growth conditions with both methane and methanol as substrate. All four growth conditions show significant differences. The most notable changes are the high glycogen content and high formate excretion for cells grown on methanol (batch), and high O2:CH4 utilization ratio for cells grown under methane limitation. Conclusions The results presented here represent the most comprehensive published bioreactor datasets for a gamma-proteobacterial methanotroph. This information shows that metabolism by M. buryatense 5GB1 differs significantly for each of the four conditions tested. O2 limitation resulted in the lowest relative O2 demand and fed-batch growth on methane the highest. Future studies are needed to understand the metabolic basis of these differences. However, these results suggest that both batch and continuous culture conditions have specific advantages, depending on the product of interest. Electronic supplementary material The online version of this article (doi:10.1186/s12934-015-0372-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alexey Gilman
- Department of Chemical Engineering, University of Washington, Seattle, WA, 98195, USA.
| | - Lieve M Laurens
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO, USA.
| | - Aaron W Puri
- Department of Chemical Engineering, University of Washington, Seattle, WA, 98195, USA.
| | - Frances Chu
- Department of Chemical Engineering, University of Washington, Seattle, WA, 98195, USA.
| | - Philip T Pienkos
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO, USA.
| | - Mary E Lidstrom
- Department of Chemical Engineering, University of Washington, Seattle, WA, 98195, USA. .,Department of Microbiology, University of Washington, Seattle, WA, 98195, USA.
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Glaring MA, Vester JK, Lylloff JE, Abu Al-Soud W, Sørensen SJ, Stougaard P. Microbial diversity in a permanently cold and alkaline environment in Greenland. PLoS One 2015; 10:e0124863. [PMID: 25915866 PMCID: PMC4411134 DOI: 10.1371/journal.pone.0124863] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 03/09/2015] [Indexed: 02/01/2023] Open
Abstract
The submarine ikaite columns located in the Ikka Fjord in Southern Greenland represent a unique, permanently cold (less than 6°C) and alkaline (above pH 10) environment and are home to a microbial community adapted to these extreme conditions. The bacterial and archaeal community inhabiting the ikaite columns and surrounding fjord was characterised by high-throughput pyrosequencing of 16S rRNA genes. Analysis of the ikaite community structure revealed the presence of a diverse bacterial community, both in the column interior and at the surface, and very few archaea. A clear difference in overall taxonomic composition was observed between column interior and surface. Whereas the surface, and in particular newly formed ikaite material, was primarily dominated by Cyanobacteria and phototrophic Proteobacteria, the column interior was dominated by Proteobacteria and putative anaerobic representatives of the Firmicutes and Bacteroidetes. The results suggest a stratification of the ikaite columns similar to that of classical soda lakes, with a light-exposed surface inhabited by primary producers and an anoxic subsurface. This was further supported by identification of major taxonomic groups with close relatives in soda lake environments, including members of the genera Rhodobaca, Dethiobacter, Thioalkalivibrio and Tindallia, as well as very abundant groups related to uncharacterised environmental sequences originally isolated from Mono Lake in California.
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Affiliation(s)
- Mikkel A. Glaring
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Jan K. Vester
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Jeanette E. Lylloff
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | | | - Søren J. Sørensen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Peter Stougaard
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
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50
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Chidambarampadmavathy K, Obulisamy P. K, Heimann K. Role of copper and iron in methane oxidation and bacterial biopolymer accumulation. Eng Life Sci 2015. [DOI: 10.1002/elsc.201400127] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Karthigeyan Chidambarampadmavathy
- Collegeof Marine and Environmental ScienceJames Cook University Townsville Queensland Australia
- Centre for Sustainable Fisheries and AquacultureJames Cook University Townsville Queensland Australia
| | - Karthikeyan Obulisamy P.
- Collegeof Marine and Environmental ScienceJames Cook University Townsville Queensland Australia
- Centre for Sustainable Fisheries and AquacultureJames Cook University Townsville Queensland Australia
| | - Kirsten Heimann
- Collegeof Marine and Environmental ScienceJames Cook University Townsville Queensland Australia
- Centre for Sustainable Fisheries and AquacultureJames Cook University Townsville Queensland Australia
- Centre for Biodiscovery and Molecular Development of TherapeuticsJames Cook University Townsville Queensland Australia
- Comparative Genomics CentreJames Cook University Townsville Queensland Australia
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