1
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Maza-Márquez P, Lee MD, Bebout BM. Community ecology and functional potential of bacteria, archaea, eukarya and viruses in Guerrero Negro microbial mat. Sci Rep 2024; 14:2561. [PMID: 38297006 PMCID: PMC10831059 DOI: 10.1038/s41598-024-52626-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Accepted: 01/22/2024] [Indexed: 02/02/2024] Open
Abstract
In this study, the microbial ecology, potential environmental adaptive mechanisms, and the potential evolutionary interlinking of genes between bacterial, archaeal and viral lineages in Guerrero Negro (GN) microbial mat were investigated using metagenomic sequencing across a vertical transect at millimeter scale. The community composition based on unique genes comprised bacteria (98.01%), archaea (1.81%), eukarya (0.07%) and viruses (0.11%). A gene-focused analysis of bacteria archaea, eukarya and viruses showed a vertical partition of the community. The greatest coverages of genes of bacteria and eukarya were detected in first layers, while the highest coverages of genes of archaea and viruses were found in deeper layers. Many genes potentially related to adaptation to the local environment were detected, such as UV radiation, multidrug resistance, oxidative stress, heavy metals, salinity and desiccation. Those genes were found in bacterial, archaeal and viral lineages with 6477, 44, and 1 genes, respectively. The evolutionary histories of those genes were studied using phylogenetic analysis, showing an interlinking between domains in GN mat.
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Affiliation(s)
- P Maza-Márquez
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, USA.
- University of Granada, Granada, Spain.
| | - M D Lee
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, USA
- Blue Marble Space Institute of Science, Seattle, WA, USA
| | - B M Bebout
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, USA
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2
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Grim SL, Stuart DG, Aron P, Levin NE, Kinsman-Costello L, Waldbauer JR, Dick GJ. Seasonal shifts in community composition and proteome expression in a sulphur-cycling cyanobacterial mat. Environ Microbiol 2023; 25:2516-2533. [PMID: 37596970 DOI: 10.1111/1462-2920.16480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 07/29/2023] [Indexed: 08/21/2023]
Abstract
Seasonal changes in light and physicochemical conditions have strong impacts on cyanobacteria, but how they affect community structure, metabolism, and biogeochemistry of cyanobacterial mats remains unclear. Light may be particularly influential for cyanobacterial mats exposed to sulphide by altering the balance of oxygenic photosynthesis and sulphide-driven anoxygenic photosynthesis. We studied temporal shifts in irradiance, water chemistry, and community structure and function of microbial mats in the Middle Island Sinkhole (MIS), where anoxic and sulphate-rich groundwater provides habitat for cyanobacteria that conduct both oxygenic and anoxygenic photosynthesis. Seasonal changes in light and groundwater chemistry were accompanied by shifts in bacterial community composition, with a succession of dominant cyanobacteria from Phormidium to Planktothrix, and an increase in diatoms, sulphur-oxidizing bacteria, and sulphate-reducing bacteria from summer to autumn. Differential abundance of cyanobacterial light-harvesting proteins likely reflects a physiological response of cyanobacteria to light level. Beggiatoa sulphur oxidation proteins were more abundant in autumn. Correlated abundances of taxa through time suggest interactions between sulphur oxidizers and sulphate reducers, sulphate reducers and heterotrophs, and cyanobacteria and heterotrophs. These results support the conclusion that seasonal change, including light availability, has a strong influence on community composition and biogeochemical cycling of sulphur and O2 in cyanobacterial mats.
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Affiliation(s)
- Sharon L Grim
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan, USA
| | - Dack G Stuart
- Cooperative Institute for Great Lakes Research, University of Michigan, Ann Arbor, Michigan, USA
| | - Phoebe Aron
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan, USA
| | - Naomi E Levin
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Jacob R Waldbauer
- Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois, USA
| | - Gregory J Dick
- Department of Earth and Environmental Sciences, Cooperative Institute for Great Lakes Research, University of Michigan, Ann Arbor, Michigan, USA
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3
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Lindberg P, Kenkel A, Bühler K. Introduction to Cyanobacteria. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2023; 183:1-24. [PMID: 37009973 DOI: 10.1007/10_2023_217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2023]
Abstract
Cyanobacteria are highly interesting microbes with the capacity for oxygenic photosynthesis. They fulfill an important purpose in nature but are also potent biocatalysts. This chapter gives a brief overview of this diverse phylum and shortly addresses the functions these organisms have in the natural ecosystems. Further, it introduces the main topics covered in this volume, which is dealing with the development and application of cyanobacteria as solar cell factories for the production of chemicals including potential fuels. We discuss cyanobacteria as industrial workhorses, present established chassis strains, and give an overview of the current target products. Genetic engineering strategies aiming at the photosynthetic efficiency as well as approaches to optimize carbon fluxes are summarized. Finally, main cultivation strategies are sketched.
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Affiliation(s)
- Pia Lindberg
- Department of Chemistry-Ångström, Uppsala University, Uppsala, Sweden
| | - Amelie Kenkel
- Helmholtzcenter for Environmental Research, Leipzig, Germany
| | - Katja Bühler
- Helmholtzcenter for Environmental Research, Leipzig, Germany.
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4
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Pavloudi C, Zafeiropoulos H. Deciphering the community structure and the functional potential of a hypersaline marsh microbial mat community. FEMS Microbiol Ecol 2022; 98:6843573. [PMID: 36416806 DOI: 10.1093/femsec/fiac141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 10/31/2022] [Accepted: 11/21/2022] [Indexed: 11/24/2022] Open
Abstract
Microbial mats are vertically stratified communities of microorganisms characterized by pronounced physiochemical gradients allowing for high species diversity and a wide range of metabolic capabilities. High Throughput Sequencing has the potential to reveal the biodiversity and function of such ecosystems in the cycling of elements. The present study combines 16S rRNA amplicon sequencing and shotgun metagenomics on a hypersaline marsh in Tristomo bay (Karpathos, Greece). Samples were collected in July 2018 and November 2019 from microbial mats, deeper sediment, aggregates observed in the water overlying the sediment, as well as sediment samples with no apparent layering. Metagenomic samples' coassembly and binning revealed 250 bacterial and 39 archaeal metagenome-assembled genomes, with completeness estimates higher than 70% and contamination less than 5%. All MAGs had KEGG Orthology terms related to osmoadaptation, with the 'salt in' strategy ones being prominent. Halobacteria and Bacteroidetes were the most abundant taxa in the mats. Photosynthesis was most likely performed by purple sulphur and nonsulphur bacteria. All samples had the capacity for sulphate reduction, dissimilatory arsenic reduction, and conversion of pyruvate to oxaloacetate. Overall, both sequencing methodologies resulted in similar taxonomic compositions and revealed that the formation of the microbial mat in this marsh exhibits seasonal variation.
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Affiliation(s)
- Christina Pavloudi
- Institute of Marine Biology, Biotechnology and Aquaculture (IMBBC), Hellenic Centre for Marine Research (HCMR), P.O. Box 2214, 71003, Heraklion, Crete, Greece.,Department of Biological Sciences, The George Washington University, 2029 G St NW, Bell Hall 302, Washington DC 20052, United States
| | - Haris Zafeiropoulos
- Institute of Marine Biology, Biotechnology and Aquaculture (IMBBC), Hellenic Centre for Marine Research (HCMR), P.O. Box 2214, 71003, Heraklion, Crete, Greece.,Department of Biology, University of Crete, Voutes University Campus, P.O. Box 2208, 70013, Heraklion, Crete, Greece.,Laboratory of Molecular Bacteriology, Rega Institute for Medical Research, Department of Microbiology, Immunology and Transplantation, KU Leuven, Herestraat 49, box 1028, 3000 Leuven, Belgium
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5
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Effect of Culture pH on Properties of Exopolymeric Substances from Synechococcus PCC7942: Implications for Carbonate Precipitation. GEOSCIENCES 2022. [DOI: 10.3390/geosciences12050210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
The role of culture conditions on the production of exopolymeric substances (EPS) by Synechococcus strain PCC7942 was investigated. Carbonate mineral precipitation in these EPS was assessed in forced precipitation experiments. Cultures were grown in HEPES-buffered medium and non-buffered medium. The pH of buffered medium remained constant at 7.5, but in non-buffered medium it increased to 9.5 within a day and leveled off at 10.5. The cell yield at harvest was twice as high in non-buffered medium than in buffered medium. High molecular weight (>10 kDa) and low molecular weight (3–10 kDa) fractions of EPS were obtained from both cultures. The cell-specific EPS production in buffered medium was twice as high as in non-buffered medium. EPS from non-buffered cultures contained more negatively charged macromolecules and more proteins than EPS from buffered cultures. The higher protein content at elevated pH may be due to the induction of carbon-concentrating mechanisms, necessary to perform photosynthetic carbon fixation in these conditions. Forced precipitation showed smaller calcite carbonate crystals in EPS from non-buffered medium and larger minerals in polymers from buffered medium. Vaterite formed only at low EPS concentrations. Experimental results are used to conceptually model the impact of pH on the potential of cyanobacterial blooms to produce minerals. We hypothesize that in freshwater systems, small crystal production may benefit the picoplankton by minimizing the mineral ballast, and thus prolonging the residence time in the photic zone, which might result in slow sinking rates.
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6
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Millimeter-scale vertical partitioning of nitrogen cycling in hypersaline mats reveals prominence of genes encoding multi-heme and prismane proteins. THE ISME JOURNAL 2022; 16:1119-1129. [PMID: 34862473 PMCID: PMC8940962 DOI: 10.1038/s41396-021-01161-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 11/09/2021] [Accepted: 11/18/2021] [Indexed: 12/01/2022]
Abstract
Microbial mats are modern analogues of the first ecosystems on the Earth. As extant representatives of microbial communities where free oxygen may have first been available on a changing planet, they offer an ecosystem within which to study the evolution of biogeochemical cycles requiring and inhibited by oxygen. Here, we report the distribution of genes involved in nitrogen metabolism across a vertical oxygen gradient at 1 mm resolution in a microbial mat using quantitative PCR (qPCR), retro-transcribed qPCR (RT-qPCR) and metagenome sequencing. Vertical patterns in the presence and expression of nitrogen cycling genes, corresponding to oxygen requiring and non-oxygen requiring nitrogen metabolism, could be seen across gradients of dissolved oxygen and ammonium. Metagenome analysis revealed that genes annotated as hydroxylamine dehydrogenase (proper enzyme designation EC 1.7.2.6, hao) and hydroxylamine reductase (hcp) were the most abundant nitrogen metabolism genes in the mat. The recovered hao genes encode hydroxylamine dehydrogenase EC 1.7.2.6 (HAO) proteins lacking the tyrosine residue present in aerobic ammonia oxidizing bacteria (AOB). Phylogenetic analysis confirmed that those proteins were more closely related to ɛHao protein present in Campylobacterota lineages (previously known as Epsilonproteobacteria) rather than oxidative HAO of AOB. The presence of hao sequences related with ɛHao protein, as well as numerous hcp genes encoding a prismane protein, suggest the presence of a nitrogen cycling pathway previously described in Nautilia profundicola as ancestral to the most commonly studied present day nitrogen cycling pathways.
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7
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Jo J, Price-Whelan A, Dietrich LEP. Gradients and consequences of heterogeneity in biofilms. Nat Rev Microbiol 2022; 20:593-607. [PMID: 35149841 DOI: 10.1038/s41579-022-00692-2] [Citation(s) in RCA: 59] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/11/2022] [Indexed: 12/15/2022]
Abstract
Historically, appreciation for the roles of resource gradients in biology has fluctuated inversely to the popularity of genetic mechanisms. Nevertheless, in microbiology specifically, widespread recognition of the multicellular lifestyle has recently brought new emphasis to the importance of resource gradients. Most microorganisms grow in assemblages such as biofilms or spatially constrained communities with gradients that influence, and are influenced by, metabolism. In this Review, we discuss examples of gradient formation and physiological differentiation in microbial assemblages growing in diverse settings. We highlight consequences of physiological heterogeneity in microbial assemblages, including division of labour and increased resistance to stress. Our impressions of microbial behaviour in various ecosystems are not complete without complementary maps of the chemical and physical geographies that influence cellular activities. A holistic view, incorporating these geographies and the genetically encoded functions that operate within them, will be essential for understanding microbial assemblages in their many roles and potential applications.
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Affiliation(s)
- Jeanyoung Jo
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Alexa Price-Whelan
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Lars E P Dietrich
- Department of Biological Sciences, Columbia University, New York, NY, USA.
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8
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Berlanga M, Palau M, Guerrero R. Community homeostasis of coastal microbial mats from the Camargue during winter (cold) and summer (hot) seasons. Ecosphere 2022. [DOI: 10.1002/ecs2.3922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Mercedes Berlanga
- Department of Biology, Environment and Health, Section Microbiology, Faculty of Pharmacy and Food Sciences University of Barcelona Barcelona Spain
| | - Montserrat Palau
- Department of Biology, Environment and Health, Section Microbiology, Faculty of Pharmacy and Food Sciences University of Barcelona Barcelona Spain
| | - Ricardo Guerrero
- Laboratory of Molecular Microbiology and Antimicrobials, Department of Pathology and Experimental Therapeutics, Faculty of Medicine University of Barcelona Barcelona Spain
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9
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Zhao M, Zhao Y, Lin W, Xiao KQ. An overview of experimental simulations of microbial activity in early Earth. Front Microbiol 2022; 13:1052831. [PMID: 36713221 PMCID: PMC9878457 DOI: 10.3389/fmicb.2022.1052831] [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: 09/24/2022] [Accepted: 12/16/2022] [Indexed: 01/15/2023] Open
Abstract
Microbial activity has shaped the evolution of the ocean and atmosphere throughout the Earth history. Thus, experimental simulations of microbial metabolism under the environment conditions of the early Earth can provide vital information regarding biogeochemical cycles and the interaction and coevolution between life and environment, with important implications for extraterrestrial exploration. In this review, we discuss the current scope and knowledge of experimental simulations of microbial activity in environments representative of those of early Earth, with perspectives on future studies. Inclusive experimental simulations involving multiple species, and cultivation experiments with more constraints on environmental conditions similar to early Earth would significantly advance our understanding of the biogeochemical cycles of the geological past.
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Affiliation(s)
- Mingyu Zhao
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
| | - Yao Zhao
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China
| | - Wei Lin
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
| | - Ke-Qing Xiao
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
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10
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Omics-Inferred Partitioning and Expression of Diverse Biogeochemical Functions in a Low-O 2 Cyanobacterial Mat Community. mSystems 2021; 6:e0104221. [PMID: 34874776 PMCID: PMC8651085 DOI: 10.1128/msystems.01042-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cyanobacterial mats profoundly influenced Earth’s biological and geochemical evolution and still play important ecological roles in the modern world. However, the biogeochemical functioning of cyanobacterial mats under persistent low-O2 conditions, which dominated their evolutionary history, is not well understood. To investigate how different metabolic and biogeochemical functions are partitioned among community members, we conducted metagenomics and metatranscriptomics on cyanobacterial mats in the low-O2, sulfidic Middle Island sinkhole (MIS) in Lake Huron. Metagenomic assembly and binning yielded 144 draft metagenome assembled genomes, including 61 of medium quality or better, and the dominant cyanobacteria and numerous Proteobacteria involved in sulfur cycling. Strains of a Phormidium autumnale-like cyanobacterium dominated the metagenome and metatranscriptome. Transcripts for the photosynthetic reaction core genes psaA and psbA were abundant in both day and night. Multiple types of psbA genes were expressed from each cyanobacterium, and the dominant psbA transcripts were from an atypical microaerobic type of D1 protein from Phormidium. Further, cyanobacterial transcripts for photosystem I genes were more abundant than those for photosystem II, and two types of Phormidium sulfide quinone reductase were recovered, consistent with anoxygenic photosynthesis via photosystem I in the presence of sulfide. Transcripts indicate active sulfur oxidation and reduction within the cyanobacterial mat, predominately by Gammaproteobacteria and Deltaproteobacteria, respectively. Overall, these genomic and transcriptomic results link specific microbial groups to metabolic processes that underpin primary production and biogeochemical cycling in a low-O2 cyanobacterial mat and suggest mechanisms for tightly coupled cycling of oxygen and sulfur compounds in the mat ecosystem. IMPORTANCE Cyanobacterial mats are dense communities of microorganisms that contain photosynthetic cyanobacteria along with a host of other bacterial species that play important yet still poorly understood roles in this ecosystem. Although such cyanobacterial mats were critical agents of Earth’s biological and chemical evolution through geological time, little is known about how they function under the low-oxygen conditions that characterized most of their natural history. Here, we performed sequencing of the DNA and RNA of modern cyanobacterial mat communities under low-oxygen and sulfur-rich conditions from the Middle Island sinkhole in Lake Huron. The results reveal the organisms and metabolic pathways that are responsible for both oxygen-producing and non-oxygen-producing photosynthesis as well as interconversions of sulfur that likely shape how much O2 is produced in such ecosystems. These findings indicate tight metabolic reactions between community members that help to explain the limited the amount of O2 produced in cyanobacterial mat ecosystems.
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11
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Triple oxygen isotope constraints on atmospheric O 2 and biological productivity during the mid-Proterozoic. Proc Natl Acad Sci U S A 2021; 118:2105074118. [PMID: 34911756 PMCID: PMC8713798 DOI: 10.1073/pnas.2105074118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2021] [Indexed: 12/16/2022] Open
Abstract
Reconstructing the history of biological productivity and atmospheric oxygen partial pressure (pO2) is a fundamental goal of geobiology. Recently, the mass-independent fractionation of oxygen isotopes (O-MIF) has been used as a tool for estimating pO2 and productivity during the Proterozoic. O-MIF, reported as Δ'17O, is produced during the formation of ozone and destroyed by isotopic exchange with water by biological and chemical processes. Atmospheric O-MIF can be preserved in the geologic record when pyrite (FeS2) is oxidized during weathering, and the sulfur is redeposited as sulfate. Here, sedimentary sulfates from the ∼1.4-Ga Sibley Formation are reanalyzed using a detailed one-dimensional photochemical model that includes physical constraints on air-sea gas exchange. Previous analyses of these data concluded that pO2 at that time was <1% PAL (times the present atmospheric level). Our model shows that the upper limit on pO2 is essentially unconstrained by these data. Indeed, pO2 levels below 0.8% PAL are possible only if atmospheric methane was more abundant than today (so that pCO2 could have been lower) or if the Sibley O-MIF data were diluted by reprocessing before the sulfates were deposited. Our model also shows that, contrary to previous assertions, marine productivity cannot be reliably constrained by the O-MIF data because the exchange of molecular oxygen (O2) between the atmosphere and surface ocean is controlled more by air-sea gas transfer rates than by biological productivity. Improved estimates of pCO2 and/or improved proxies for Δ'17O of atmospheric O2 would allow tighter constraints to be placed on mid-Proterozoic pO2.
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12
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Kindler GS, Wong HL, Larkum AWD, Johnson M, MacLeod FI, Burns BP. Genome-resolved metagenomics provides insights into the functional complexity of microbial mats in Blue Holes, Shark Bay. FEMS Microbiol Ecol 2021; 98:6448473. [PMID: 34865013 DOI: 10.1093/femsec/fiab158] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 11/30/2021] [Indexed: 11/13/2022] Open
Abstract
The present study describes for the first time the community composition and functional potential of the microbial mats found in the supratidal, gypsum-rich, and hypersaline region of Blue Holes, Shark Bay. This was achieved via high throughput metagenomic sequencing of total mat community DNA and complementary analyses using hyperspectral confocal microscopy. Mat communities were dominated by Proteobacteria (29%), followed by Bacteroidetes/Chlorobi Group (11%), and Planctomycetes (10%). These mats were found to also harbor a diverse community of potentially novel microorganisms including members from the DPANN, Asgard archaea, and Candidate Phyla Radiation, with highest diversity found in the lower regions (∼14-20 mm depth) of the mat. In addition to pathways for major metabolic cycles, a range of putative rhodopsins with previously uncharacterized motifs and functions were identified along with heliorhodopsins and putative schizorhodopsins. Critical microbial interactions were also inferred, and from 117 medium-to-high quality metagenome-assembled genomes (MAGs), viral defense mechanisms (CRISPR, BREX, and DISARM), elemental transport, osmoprotection, heavy metal and UV resistance were also detected. These analyses have provided a greater understanding of these distinct mat systems in Shark Bay, including key insights into adaptive responses and proposing that photoheterotrophy may be an important lifestyle in Blue Holes.
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Affiliation(s)
- Gareth S Kindler
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Hon Lun Wong
- Department of Aquatic Microbial Ecology, Institute of Hydrobiology, Biology Centre of the Academy of Sciences of the Czech Republic, České Budějovice, Czech Republic.,Australian Centre for Astrobiology, University of New South Wales Sydney, Sydney, NSW, Australia
| | - Anthony W D Larkum
- Climate Change Cluster, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
| | - Michael Johnson
- Climate Change Cluster, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
| | - Fraser I MacLeod
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia.,Australian Centre for Astrobiology, University of New South Wales Sydney, Sydney, NSW, Australia
| | - Brendan P Burns
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia.,Australian Centre for Astrobiology, University of New South Wales Sydney, Sydney, NSW, Australia
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13
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Bhattarai B, Bhattacharjee AS, Coutinho FH, Goel RK. Viruses and Their Interactions With Bacteria and Archaea of Hypersaline Great Salt Lake. Front Microbiol 2021; 12:701414. [PMID: 34650523 PMCID: PMC8506154 DOI: 10.3389/fmicb.2021.701414] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 09/06/2021] [Indexed: 01/15/2023] Open
Abstract
Viruses play vital biogeochemical and ecological roles by (a) expressing auxiliary metabolic genes during infection, (b) enhancing the lateral transfer of host genes, and (c) inducing host mortality. Even in harsh and extreme environments, viruses are major players in carbon and nutrient recycling from organic matter. However, there is much that we do not yet understand about viruses and the processes mediated by them in the extreme environments such as hypersaline habitats. The Great Salt Lake (GSL) in Utah, United States is a hypersaline ecosystem where the biogeochemical role of viruses is poorly understood. This study elucidates the diversity of viruses and describes virus–host interactions in GSL sediments along a salinity gradient. The GSL sediment virosphere consisted of Haloviruses (32.07 ± 19.33%) and members of families Siphoviridae (39.12 ± 19.8%), Myoviridae (13.7 ± 6.6%), and Podoviridae (5.43 ± 0.64%). Our results demonstrate that salinity alongside the concentration of organic carbon and inorganic nutrients (nitrogen and phosphorus) governs the viral, bacteria, and archaeal diversity in this habitat. Computational host predictions for the GSL viruses revealed a wide host range with a dominance of viruses that infect Proteobacteria, Actinobacteria, and Firmicutes. Identification of auxiliary metabolic genes for photosynthesis (psbA), carbon fixation (rbcL, cbbL), formaldehyde assimilation (SHMT), and nitric oxide reduction (NorQ) shed light on the roles played by GSL viruses in biogeochemical cycles of global relevance.
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Affiliation(s)
- Bishav Bhattarai
- Department of Civil and Environmental Engineering, The University of Utah, Salt Lake City, UT, United States
| | - Ananda S Bhattacharjee
- Carl R. Woese Institute for Genomic Biology, The University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Felipe H Coutinho
- Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández, Alicante, Spain
| | - Ramesh K Goel
- Department of Civil and Environmental Engineering, The University of Utah, Salt Lake City, UT, United States
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14
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Hazaimeh MD, Ahmed ES. Bioremediation perspectives and progress in petroleum pollution in the marine environment: a review. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:54238-54259. [PMID: 34387817 DOI: 10.1007/s11356-021-15598-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 07/19/2021] [Indexed: 06/13/2023]
Abstract
The marine environment is often affected by petroleum hydrocarbon pollution due to industrial activities and petroleum accidents. This pollution has recalcitrant and persistent compounds that pose a high risk to the ecological system and human health. For this reason, the world claims to seek to clean up these pollutants. Bioremediation is an attractive approach for removing petroleum pollution. It is considered a low-cost and highly effective approach with fewer side effects compared to chemical and physical techniques. This depends on the metabolic capability of microorganisms involved in the degradation of hydrocarbons through enzymatic reactions. Bioremediation activities mostly depend on environmental conditions such as temperature, pH, salinity, pressure, and nutrition availability. Understanding the effects of environmental conditions on microbial hydrocarbon degraders and microbial interactions with hydrocarbon compounds could be assessed for the successful degradation of petroleum pollution. The current review provides a critical view of petroleum pollution in seawater, the bioavailability of petroleum compounds, the contribution of microorganisms in petroleum degradation, and the mechanisms of degradation under aerobic and anaerobic conditions. We consider different biodegradation approaches such as biostimulation, bioaugmentation, and phytoremediation.
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Affiliation(s)
- Mohammad Daher Hazaimeh
- Department of Biology, College of Science in Zulfi, Majmaah University, Majmaah-11952, Saudi Arabia.
| | - Enas S Ahmed
- Department of Biology, College of Science in Zulfi, Majmaah University, Majmaah-11952, Saudi Arabia
- Department of Botany and Microbiology, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt
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15
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Carreira C, Lønborg C, Kühl M, Lillebø AI, Sandaa RA, Villanueva L, Cruz S. Fungi and viruses as important players in microbial mats. FEMS Microbiol Ecol 2021; 96:5910486. [PMID: 32966583 DOI: 10.1093/femsec/fiaa187] [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: 05/04/2020] [Accepted: 09/18/2020] [Indexed: 11/14/2022] Open
Abstract
Microbial mats are compacted, surface-associated microbial ecosystems reminiscent of the first living communities on early Earth. While often considered predominantly prokaryotic, recent findings show that both fungi and viruses are ubiquitous in microbial mats, albeit their functional roles remain unknown. Fungal research has mostly focused on terrestrial and freshwater ecosystems where fungi are known as important recyclers of organic matter, whereas viruses are exceptionally abundant and important in aquatic ecosystems. Here, viruses have shown to affect organic matter cycling and the diversity of microbial communities by facilitating horizontal gene transfer and cell lysis. We hypothesise fungi and viruses to have similar roles in microbial mats. Based on the analysis of previous research in terrestrial and aquatic ecosystems, we outline novel hypotheses proposing strong impacts of fungi and viruses on element cycling, food web structure and function in microbial mats, and outline experimental approaches for studies needed to understand these interactions.
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Affiliation(s)
- Cátia Carreira
- ECOMARE, CESAM-Centre for Environmental and Marine Studies, Departament of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
| | - Christian Lønborg
- Section for Applied Marine Ecology and Modelling, Department of Bioscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Michael Kühl
- Marine Biological Section, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark
| | - Ana I Lillebø
- ECOMARE, CESAM-Centre for Environmental and Marine Studies, Departament of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
| | - Ruth-Anne Sandaa
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Laura Villanueva
- Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, Utrecht University, Texel, The Netherlands
| | - Sónia Cruz
- ECOMARE, CESAM-Centre for Environmental and Marine Studies, Departament of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
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16
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Buetti-Dinh A, Ruinelli M, Czerski D, Scapozza C, Martignier A, Roman S, Caminada A, Tonolla M. Geochemical and metagenomics study of a metal-rich, green-turquoise-coloured stream in the southern Swiss Alps. PLoS One 2021; 16:e0248877. [PMID: 33784327 PMCID: PMC8009434 DOI: 10.1371/journal.pone.0248877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 03/07/2021] [Indexed: 12/02/2022] Open
Abstract
The Swiss Alpine environments are poorly described from a microbiological perspective. Near the Greina plateau in the Camadra valley in Ticino (southern Swiss Alps), a green-turquoise-coloured water spring streams off the mountain cliffs. Geochemical profiling revealed naturally elevated concentrations of heavy metals such as copper, lithium, zinc and cadmium, which are highly unusual for the geomorphology of the region. Of particular interest, was the presence of a thick biofilm, that was revealed by microscopic analysis to be mainly composed of Cyanobacteria. A metagenome was further assembled to detail the genes found in this environment. A multitude of genes for resistance/tolerance to high heavy metal concentrations were indeed found, such as, various transport systems, and genes involved in the synthesis of extracellular polymeric substances (EPS). EPS have been evoked as a central component in photosynthetic environments rich in heavy metals, for their ability to drive the sequestration of toxic, positively-charged metal ions under high regimes of cyanobacteria-driven photosynthesis. The results of this study provide a geochemical and microbiological description of this unusual environment in the southern Swiss Alps, the role of cyanobacterial photosynthesis in metal resistance, and the potential role of such microbial community in bioremediation of metal-contaminated environments.
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Affiliation(s)
- Antoine Buetti-Dinh
- Laboratory of Applied Microbiology (LMA), Department of Environment, Constructions and Design (DACD), University of Applied Sciences of Southern Switzerland (SUPSI), Bellinzona, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
- * E-mail: (ABD); (MT)
| | - Michela Ruinelli
- Laboratory of Applied Microbiology (LMA), Department of Environment, Constructions and Design (DACD), University of Applied Sciences of Southern Switzerland (SUPSI), Bellinzona, Switzerland
| | - Dorota Czerski
- Institute of Earth Sciences, University of Applied Sciences of Southern Switzerland (SUPSI), Trevano, Canobbio, Switzerland
| | - Cristian Scapozza
- Institute of Earth Sciences, University of Applied Sciences of Southern Switzerland (SUPSI), Trevano, Canobbio, Switzerland
| | - Agathe Martignier
- Department of Earth Sciences, University of Geneva, Geneva, Switzerland
| | - Samuele Roman
- Laboratory of Applied Microbiology (LMA), Department of Environment, Constructions and Design (DACD), University of Applied Sciences of Southern Switzerland (SUPSI), Bellinzona, Switzerland
- Alpine Biology Center Foundation, Bellinzona, Switzerland
| | - Annapaola Caminada
- Laboratory of Applied Microbiology (LMA), Department of Environment, Constructions and Design (DACD), University of Applied Sciences of Southern Switzerland (SUPSI), Bellinzona, Switzerland
| | - Mauro Tonolla
- Laboratory of Applied Microbiology (LMA), Department of Environment, Constructions and Design (DACD), University of Applied Sciences of Southern Switzerland (SUPSI), Bellinzona, Switzerland
- Alpine Biology Center Foundation, Bellinzona, Switzerland
- Microbiology Unit, Department of Botany and Plant Biology, University of Geneva, Geneva, Switzerland
- * E-mail: (ABD); (MT)
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17
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The Abundance and Diversity of Fungi in a Hypersaline Microbial Mat from Guerrero Negro, Baja California, México. J Fungi (Basel) 2021; 7:jof7030210. [PMID: 33809206 PMCID: PMC7999539 DOI: 10.3390/jof7030210] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 03/03/2021] [Accepted: 03/09/2021] [Indexed: 01/15/2023] Open
Abstract
The abundance and diversity of fungi were evaluated in a hypersaline microbial mat from Guerrero Negro, México, using a combination of quantitative polymerase chain reaction (qPCR) amplification of domain-specific primers, and metagenomic sequencing. Seven different layers were analyzed in the mat (Layers 1–7) at single millimeter resolution (from the surface to 7 mm in depth). The number of copies of the 18S rRNA gene of fungi ranged between 106 and 107 copies per g mat, being two logarithmic units lower than of the 16S rRNA gene of bacteria. The abundance of 18S rRNA genes of fungi varied significantly among the layers with layers 2–5 mm from surface contained the highest numbers of copies. Fifty-six fungal taxa were identified by metagenomic sequencing, classified into three different phyla: Ascomycota, Basidiomycota and Microsporidia. The prevalent genera of fungi were Thermothelomyces, Pyricularia, Fusarium, Colletotrichum, Aspergillus, Botrytis, Candida and Neurospora. Genera of fungi identified in the mat were closely related to genera known to have saprotrophic and parasitic lifestyles, as well as genera related to human and plant pathogens and fungi able to perform denitrification. This research suggests that fungi in the mat may participate in nutrient recycling, modification of community composition through parasitic activities, and denitrification.
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18
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Finke N, Simister RL, O'Neil AH, Nomosatryo S, Henny C, MacLean LC, Canfield DE, Konhauser K, Lalonde SV, Fowle DA, Crowe SA. Mesophilic microorganisms build terrestrial mats analogous to Precambrian microbial jungles. Nat Commun 2019; 10:4323. [PMID: 31541087 PMCID: PMC6754388 DOI: 10.1038/s41467-019-11541-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 07/03/2019] [Indexed: 12/02/2022] Open
Abstract
Development of Archean paleosols and patterns of Precambrian rock weathering suggest colonization of continents by subaerial microbial mats long before evolution of land plants in the Phanerozoic Eon. Modern analogues for such mats, however, have not been reported, and possible biogeochemical roles of these mats in the past remain largely conceptual. We show that photosynthetic, subaerial microbial mats from Indonesia grow on mafic bedrocks at ambient temperatures and form distinct layers with features similar to Precambrian mats and paleosols. Such subaerial mats could have supported a substantial aerobic biosphere, including nitrification and methanotrophy, and promoted methane emissions and oxidative weathering under ostensibly anoxic Precambrian atmospheres. High C-turnover rates and cell abundances would have made these mats prime locations for early microbial diversification. Growth of landmass in the late Archean to early Proterozoic Eons could have reorganized biogeochemical cycles between land and sea impacting atmospheric chemistry and climate.
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Affiliation(s)
- N Finke
- Departments of Microbiology and Immunology and Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
- Nordic center for earth evolution (NordCEE), University of Southern Denmark, Odense, Denmark
| | - R L Simister
- Departments of Microbiology and Immunology and Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
| | | | - S Nomosatryo
- Research center for Limnology, Indonesian Institute of Sciences (LIPI), Jawa Barat, Indonesia
- GFZ German Research Centre for Geosciences, Potsdam, Germany
| | - C Henny
- Research center for Limnology, Indonesian Institute of Sciences (LIPI), Jawa Barat, Indonesia
| | | | - D E Canfield
- Nordic center for earth evolution (NordCEE), University of Southern Denmark, Odense, Denmark
| | - K Konhauser
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Canada
| | - S V Lalonde
- European Institute for Marine Studies, Technopôle Brest-Iroise, Plouzané, France
| | - D A Fowle
- Department of Geology, University of Kansas, Lawrence, KS, USA
| | - S A Crowe
- Departments of Microbiology and Immunology and Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, Canada.
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19
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Reinold M, Wong HL, MacLeod FI, Meltzer J, Thompson A, Burns BP. The Vulnerability of Microbial Ecosystems in A Changing Climate: Potential Impact in Shark Bay. Life (Basel) 2019; 9:life9030071. [PMID: 31480795 PMCID: PMC6789446 DOI: 10.3390/life9030071] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 08/22/2019] [Accepted: 08/28/2019] [Indexed: 12/26/2022] Open
Abstract
The potential impact of climate change on eukaryotes, including humans, has been relatively well described. In contrast, the contribution and susceptibility of microorganisms to a changing climate have, until recently, received relatively less attention. In this review, the importance of microorganisms in the climate change discourse is highlighted. Microorganisms are responsible for approximately half of all primary production on earth, support all forms of macroscopic life whether directly or indirectly, and often persist in “extreme” environments where most other life are excluded. In short, microorganisms are the life support system of the biosphere and therefore must be included in decision making regarding climate change. Any effects climate change will have on microorganisms will inevitably impact higher eukaryotes and the activity of microbial communities in turn can contribute to or alleviate the severity of the changing climate. It is of vital importance that unique, fragile, microbial ecosystems are a focus of research efforts so that their resilience to extreme weather events and climate change are thoroughly understood and that conservation efforts can be implemented as a response. One such ecosystem under threat are the evolutionarily significant microbial mats and stromatolites, such as those present in Shark Bay, Western Australia. Climate change models have suggested the duration and severity of extreme weather events in this region will increase, along with rising temperatures, sea levels, and ocean acidification. These changes could upset the delicate balance that fosters the development of microbial mats and stromatolites in Shark Bay. Thus, the challenges facing Shark Bay microbial communities will be presented here as a specific case study.
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Affiliation(s)
- Max Reinold
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney 2052, Australia
- Australian Centre for Astrobiology; The University of New South Wales Sydney 2052, Australia
| | - Hon Lun Wong
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney 2052, Australia
- Australian Centre for Astrobiology; The University of New South Wales Sydney 2052, Australia
| | - Fraser I MacLeod
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney 2052, Australia
- Australian Centre for Astrobiology; The University of New South Wales Sydney 2052, Australia
| | - Julia Meltzer
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney 2052, Australia
- Australian Centre for Astrobiology; The University of New South Wales Sydney 2052, Australia
| | - April Thompson
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney 2052, Australia
- Australian Centre for Astrobiology; The University of New South Wales Sydney 2052, Australia
| | - Brendan P Burns
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney 2052, Australia.
- Australian Centre for Astrobiology; The University of New South Wales Sydney 2052, Australia.
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20
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Patel HM, Rastogi RP, Trivedi U, Madamwar D. Cyanobacterial diversity in mat sample obtained from hypersaline desert, Rann of Kachchh. 3 Biotech 2019; 9:304. [PMID: 31355113 DOI: 10.1007/s13205-019-1837-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 07/15/2019] [Indexed: 01/18/2023] Open
Abstract
Rann of Kachchh (RoK) is a unique geoformation, which is exposed to dynamic environmental changes such as salinity, temperature, and nutrients throughout the year. In this study, the pooled mat sample was examined for the cyanobacterial community structure using culture-dependent and culture-independent approaches. Taxonomic profiling was studied using amplicon sequencing that revealed the enrichment of Pseudanabaenales and Oscillatoriales by QIIME and MG-RAST, respectively. Other abundant orders were represented by Chroococcales, Nostocales, and unclassified cyanobacteria by both approaches. Nine cyanobacterial cultures were isolated from mat samples showing 90-98% similarities with available sequences in GenBank. The culture-dependent study suggested that mat was dominated by cyanobacterial orders such as Oscillatoriales-filamentous and Chroococcales-unicellular. Our results from the culture-dependent approach also indicated that despite high similarities in gene sequences, six cyanobacteria fall into the separate clade in the phylogenetic analysis that could be signs of evolution due to an extreme environment. Cultured isolates are correlated well with abundant taxa from amplicon sequencing. Further, protein profiling was done specifically for phycobiliproteins which will be helpful to elucidate their roles in light harvesting and energy transfer mechanism in the unique environment of RoK.
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21
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Smith CL, Mayorova TD. Insights into the evolution of digestive systems from studies of Trichoplax adhaerens. Cell Tissue Res 2019; 377:353-367. [PMID: 31270610 DOI: 10.1007/s00441-019-03057-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 06/09/2019] [Indexed: 01/01/2023]
Abstract
Trichoplax, a member of the phylum Placozoa, is a tiny ciliated marine animal that glides on surfaces feeding on algae and cyanobacteria. It stands out from other animals in that it lacks an internal digestive system and, instead, digests food trapped under its lower surface. Here we review recent work on the phenotypes of its six cell types and their roles in digestion and feeding behavior. Phylogenomic analyses place Placozoa as sister to Eumetazoa, the clade that includes Cnidaria and Bilateria. Comparing the phenotypes of cells in Trichoplax to those of cells in the digestive epithelia of Eumetazoa allows us to make inferences about the cell types and mode of feeding of their ancestors. From our increasingly mechanistic understanding of feeding in Trichoplax, we get a glimpse into how primitive animals may have hunted and consumed food prior to the evolution of neurons, muscles, and internal digestive systems.
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Affiliation(s)
- Carolyn L Smith
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Tatiana D Mayorova
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
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22
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Burganskaya EI, Bryantseva IA, Krutkina MS, Grouzdev DS, Gorlenko VM. Bacterial communities of the microbial mats of Chokrak sulfide springs. Arch Microbiol 2019; 201:795-805. [DOI: 10.1007/s00203-019-01648-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 03/05/2019] [Accepted: 03/07/2019] [Indexed: 12/01/2022]
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23
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Efficient recycling of nutrients in modern and past hypersaline environments. Sci Rep 2019; 9:3718. [PMID: 30842491 PMCID: PMC6403304 DOI: 10.1038/s41598-019-40174-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 02/11/2019] [Indexed: 11/09/2022] Open
Abstract
The biogeochemistry of hypersaline environments is strongly influenced by changes in biological processes and physicochemical parameters. Although massive evaporation events have occurred repeatedly throughout Earth history, their biogeochemical cycles and global impact remain poorly understood. Here, we provide the first nitrogen isotopic data for nutrients and chloropigments from modern shallow hypersaline environments (solar salterns, Trapani, Italy) and apply the obtained insights to δ15N signatures of the Messinian salinity crisis (MSC) in the late Miocene. Concentrations and δ15N of chlorophyll a, bacteriochlorophyll a, nitrate, and ammonium in benthic microbial mats indicate that inhibition of nitrification suppresses denitrification and anammox, resulting in efficient ammonium recycling within the mats and high primary productivity. We also suggest that the release of 15N-depleted NH3(gas) with increasing salinity enriches ammonium 15N in surface brine (≈34.0‰). Such elevated δ15N is also recorded in geoporphyrins isolated from sediments of the MSC peak (≈20‰), reflecting ammonium supply sufficient for sustaining phototrophic primary production. We propose that efficient nutrient supply combined with frequent bottom-water anoxia and capping of organic-rich sediments by evaporites of the Mediterranean MSC could have contributed to atmospheric CO2 reduction during the late Miocene.
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24
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Shen Y, Thiel V, Duda JP, Reitner J. Tracing the fate of steroids through a hypersaline microbial mat (Kiritimati, Kiribati/Central Pacific). GEOBIOLOGY 2018; 16:307-318. [PMID: 29577559 DOI: 10.1111/gbi.12279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 01/29/2018] [Indexed: 06/08/2023]
Abstract
Eukaryotic steranes are typically absent or occur in very low concentrations in Precambrian sedimentary rocks. However, it is as yet unclear whether this may reflect low source inputs or a preservational bias. For instance, it has been proposed that eukaryotic lipids were profoundly degraded in benthic microbial mats that were ubiquitous prior to the advent of vertical bioturbation in the Cambrian ("mat-seal effect"). It is therefore important to test the microbial turnover and degradation of eukaryotic steroids in real-world microbial mats. Here we assessed steroid inventories in different layers of a microbial mat from a hypersaline lake on Kiritimati (Central Pacific). Various eukaryote-derived C27 -C30 steroids were detected in all mat layers. These compounds most likely entered the mat system as unsaturated sterols from the water column or the topmost mat, and were progressively altered during burial in the deeper, anoxic mat layers over c. 103 years. This is reflected by increasing proportions of saturated sterols and sterenes, as well as the presence of thiosteranes in certain horizons. Sterol alteration can partly be assigned to microbial transformation but is also due to chemical reactions promoted by the reducing environment in the deeper mat layers. Notably, however, compounds with a sterane skeleton were similarly abundant in all mat layers and their absolute concentrations did not show any systematic decrease. The observed decrease of steroid/hopanoid ratios with depth may thus rather indicate a progressive "dilution" by lipids derived from heterotrophic bacteria. Further, pyrolysis revealed that steroids, in contrast to hopanoids, were not sequestered into non-extractable organic matter. This may lead to a preservational bias against steroids during later stages of burial. Taken together, steroid preservation in the microbial mat is not only controlled by heterotrophic degradation, but rather reflects a complex interplay of taphonomic processes.
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Affiliation(s)
- Y Shen
- Department of Geobiology, Geoscience Centre, Georg-August-Universität Göttingen, Göttingen, Germany
| | - V Thiel
- Department of Geobiology, Geoscience Centre, Georg-August-Universität Göttingen, Göttingen, Germany
| | - J-P Duda
- Department of Geobiology, Geoscience Centre, Georg-August-Universität Göttingen, Göttingen, Germany
- 'Origin of Life' Group, Göttingen Academy of Sciences and Humanities, Göttingen, Germany
| | - J Reitner
- Department of Geobiology, Geoscience Centre, Georg-August-Universität Göttingen, Göttingen, Germany
- 'Origin of Life' Group, Göttingen Academy of Sciences and Humanities, Göttingen, Germany
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25
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Prieto-Barajas CM, Valencia-Cantero E, Santoyo G. Microbial mat ecosystems: Structure types, functional diversity, and biotechnological application. ELECTRON J BIOTECHN 2018. [DOI: 10.1016/j.ejbt.2017.11.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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26
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Gomes ML, Fike DA, Bergmann KD, Jones C, Knoll AH. Environmental insights from high-resolution (SIMS) sulfur isotope analyses of sulfides in Proterozoic microbialites with diverse mat textures. GEOBIOLOGY 2018; 16:17-34. [PMID: 29047210 DOI: 10.1111/gbi.12265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 09/01/2017] [Indexed: 06/07/2023]
Abstract
In modern microbial mats, hydrogen sulfide shows pronounced sulfur isotope (δ34 S) variability over small spatial scales (~50‰ over <4 mm), providing information about microbial sulfur cycling within different ecological niches in the mat. In the geological record, the location of pyrite formation, overprinting from mat accretion, and post-depositional alteration also affect both fine-scale δ34 S patterns and bulk δ34 Spyrite values. We report μm-scale δ34 S patterns in Proterozoic samples with well-preserved microbial mat textures. We show a well-defined relationship between δ34 S values and sulfide mineral grain size and type. Small pyrite grains (<25 μm) span a large range, tending toward high δ34 S values (-54.5‰ to 11.7‰, mean: -14.4‰). Larger pyrite grains (>25 μm) have low but equally variable δ34 S values (-61.0‰ to -10.5‰, mean: -44.4‰). In one sample, larger sphalerite grains (>35 μm) have intermediate and essentially invariant δ34 S values (-22.6‰ to -15.6‰, mean: -19.4‰). We suggest that different sulfide mineral populations reflect separate stages of formation. In the first stage, small pyrite grains form near the mat surface along a redox boundary where high rates of sulfate reduction, partial closed-system sulfate consumption in microenvironments, and/or sulfide oxidation lead to high δ34 S values. In another stage, large sphalerite grains with low δ34 S values grow along the edges of pore spaces formed from desiccation of the mat. Large pyrite grains form deeper in the mat at slower sulfate reduction rates, leading to low δ34 Ssulfide values. We do not see evidence for significant 34 S-enrichment in bulk pore water sulfide at depth in the mat due to closed-system Rayleigh fractionation effects. On a local scale, Rayleigh fractionation influences the range of δ34 S values measured for individual pyrite grains. Fine-scale analyses of δ34 Spyrite patterns can thus be used to extract environmental information from ancient microbial mats and aid in the interpretation of bulk δ34 Spyrite records.
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Affiliation(s)
- M L Gomes
- Washington University, Saint Louis, MO, USA
- Harvard University, Cambridge, MA, USA
| | - D A Fike
- Washington University, Saint Louis, MO, USA
| | - K D Bergmann
- Massachusettes Institute of Technology, Cambridge, MA, USA
| | - C Jones
- Washington University, Saint Louis, MO, USA
| | - A H Knoll
- Harvard University, Cambridge, MA, USA
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27
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D'haeseleer P, Lee JZ, Prufert-Bebout L, Burow LC, Detweiler AM, Weber PK, Karaoz U, Brodie EL, Glavina Del Rio T, Tringe SG, Bebout BM, Pett-Ridge J. Metagenomic analysis of intertidal hypersaline microbial mats from Elkhorn Slough, California, grown with and without molybdate. Stand Genomic Sci 2017; 12:67. [PMID: 29167704 PMCID: PMC5688640 DOI: 10.1186/s40793-017-0279-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 10/25/2017] [Indexed: 11/10/2022] Open
Abstract
Cyanobacterial mats are laminated microbial ecosystems which occur in highly diverse environments and which may provide a possible model for early life on Earth. Their ability to produce hydrogen also makes them of interest from a biotechnological and bioenergy perspective. Samples of an intertidal microbial mat from the Elkhorn Slough estuary in Monterey Bay, California, were transplanted to a greenhouse at NASA Ames Research Center to study a 24-h diel cycle, in the presence or absence of molybdate (which inhibits biohydrogen consumption by sulfate reducers). Here, we present metagenomic analyses of four samples that will be used as references for future metatranscriptomic analyses of this diel time series.
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Affiliation(s)
| | | | | | - Luke C Burow
- NASA Ames Research Center, Moffett Field, CA USA.,Stanford University, Stanford, CA USA
| | - Angela M Detweiler
- NASA Ames Research Center, Moffett Field, CA USA.,Bay Area Environmental Research Institute, Petaluma, CA USA
| | - Peter K Weber
- Lawrence Livermore National Laboratory, Livermore, CA USA
| | - Ulas Karaoz
- Lawrence Berkeley National Laboratory, Berkeley, CA USA
| | - Eoin L Brodie
- Lawrence Berkeley National Laboratory, Berkeley, CA USA
| | - Tijana Glavina Del Rio
- Lawrence Berkeley National Laboratory, Berkeley, CA USA.,Department of Energy Joint Genome Institute, Walnut Creek, CA USA
| | - Susannah G Tringe
- Lawrence Berkeley National Laboratory, Berkeley, CA USA.,Department of Energy Joint Genome Institute, Walnut Creek, CA USA
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28
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Maegaard K, Nielsen LP, Revsbech NP. Hydrogen Dynamics in Cyanobacteria Dominated Microbial Mats Measured by Novel Combined H 2/H 2S and H 2/O 2 Microsensors. Front Microbiol 2017; 8:2022. [PMID: 29093704 PMCID: PMC5651244 DOI: 10.3389/fmicb.2017.02022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 10/04/2017] [Indexed: 11/13/2022] Open
Abstract
Hydrogen may accumulate to micromolar concentrations in cyanobacterial mat communities from various environments, but the governing factors for this accumulation are poorly described. We used newly developed sensors allowing for simultaneous measurement of H2S and H2 or O2 and H2 within the same point to elucidate the interactions between oxygen, sulfate reducing bacteria, and H2 producing microbes. After onset of darkness and subsequent change from oxic to anoxic conditions within the uppermost ∼1 mm of the mat, H2 accumulated to concentrations of up to 40 μmol L-1 in the formerly oxic layer, but with high variability among sites and sampling dates. The immediate onset of H2 production after darkening points to fermentation as the main H2 producing process in this mat. The measured profiles indicate that a gradual disappearance of the H2 peak was mainly due to the activity of sulfate reducing bacteria that invaded the formerly oxic surface layer from below, or persisted in an inactive state in the oxic mat during illumination. The absence of significant H2 consumption in the formerly oxic mat during the first ∼30 min after onset of anoxic conditions indicated absence of active sulfate reducers in this layer during the oxic period. Addition of the methanogenesis inhibitor BES led to increase in H2, indicating that methanogens contributed to the consumption of H2. Both H2 formation and consumption seemed unaffected by the presence/absence of H2S.
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Affiliation(s)
| | | | - Niels P. Revsbech
- Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
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29
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Wong HL, Visscher PT, White RA, Smith DL, Patterson MM, Burns BP. Dynamics of archaea at fine spatial scales in Shark Bay mat microbiomes. Sci Rep 2017; 7:46160. [PMID: 28397816 PMCID: PMC5387419 DOI: 10.1038/srep46160] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 03/09/2017] [Indexed: 01/07/2023] Open
Abstract
The role of archaea in microbial mats is poorly understood. Delineating the spatial distribution of archaea with mat depth will enable resolution of putative niches in these systems. In the present study, high throughput amplicon sequencing was undertaken in conjunction with analysis of key biogeochemical properties of two mats (smooth and pustular) from Shark Bay, Australia. One-way analysis of similarity tests indicated the archaeal community structures of smooth and pustular mats were significantly different (global R = 1, p = 0.1%). Smooth mats possessed higher archaeal diversity, dominated by Parvarchaeota. The methanogenic community in smooth mats was dominated by hydrogenotrophic Methanomicrobiales, as well as methylotrophic Methanosarcinales, Methanococcales, Methanobacteriales and Methanomassiliicoccaceae. Pustular mats were enriched with Halobacteria and Parvarchaeota. Key metabolisms (bacterial and archaeal) were measured, and the rates of oxygen production/consumption and sulfate reduction were up to four times higher in smooth than in pustular mats. Methane production peaked in the oxic layers and was up to seven-fold higher in smooth than pustular mats. The finding of an abundance of anaerobic methanogens enriched at the surface where oxygen levels were highest, coupled with peak methane production in the oxic zone, suggests putative surface anoxic niches in these microbial mats.
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Affiliation(s)
- Hon Lun Wong
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia.,Australian Centre for Astrobiology, University of New South Wales Sydney, Australia
| | - Pieter T Visscher
- Department of Marine Sciences, University of Connecticut, USA.,Australian Centre for Astrobiology, University of New South Wales Sydney, Australia
| | - Richard Allen White
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Daniela-Lee Smith
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
| | | | - Brendan P Burns
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia.,Australian Centre for Astrobiology, University of New South Wales Sydney, Australia
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Phalak P, Chen J, Carlson RP, Henson MA. Metabolic modeling of a chronic wound biofilm consortium predicts spatial partitioning of bacterial species. BMC SYSTEMS BIOLOGY 2016; 10:90. [PMID: 27604263 PMCID: PMC5015247 DOI: 10.1186/s12918-016-0334-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 08/25/2016] [Indexed: 12/18/2022]
Abstract
Background Chronic wounds are often colonized by consortia comprised of different bacterial species growing as biofilms on a complex mixture of wound exudate. Bacteria growing in biofilms exhibit phenotypes distinct from planktonic growth, often rendering the application of antibacterial compounds ineffective. Computational modeling represents a complementary tool to experimentation for generating fundamental knowledge and developing more effective treatment strategies for chronic wound biofilm consortia. Results We developed spatiotemporal models to investigate the multispecies metabolism of a biofilm consortium comprised of two common chronic wound isolates: the aerobe Pseudomonas aeruginosa and the facultative anaerobe Staphylococcus aureus. By combining genome-scale metabolic reconstructions with partial differential equations for metabolite diffusion, the models were able to provide both temporal and spatial predictions with genome-scale resolution. The models were used to analyze the metabolic differences between single species and two species biofilms and to demonstrate the tendency of the two bacteria to spatially partition in the multispecies biofilm as observed experimentally. Nutrient gradients imposed by supplying glucose at the bottom and oxygen at the top of the biofilm induced spatial partitioning of the two species, with S. aureus most concentrated in the anaerobic region and P. aeruginosa present only in the aerobic region. The two species system was predicted to support a maximum biofilm thickness much greater than P. aeruginosa alone but slightly less than S. aureus alone, suggesting an antagonistic metabolic effect of P. aeruginosa on S. aureus. When each species was allowed to enhance its growth through consumption of secreted metabolic byproducts assuming identical uptake kinetics, the competitiveness of P. aeruginosa was further reduced due primarily to the more efficient lactate metabolism of S. aureus. Lysis of S. aureus by a small molecule inhibitor secreted from P. aeruginosa and/or P. aeruginosa aerotaxis were predicted to substantially increase P. aeruginosa competitiveness in the aerobic region, consistent with in vitro experimental studies. Conclusions Our biofilm modeling approach allows the prediction of individual species metabolism and interspecies interactions in both time and space with genome-scale resolution. This study yielded new insights into the multispecies metabolism of a chronic wound biofilm, in particular metabolic factors that may lead to spatial partitioning of the two bacterial species. We believe that P. aeruginosa lysis of S. aureus combined with nutrient competition is a particularly relevant scenario for which model predictions could be tested experimentally. Electronic supplementary material The online version of this article (doi:10.1186/s12918-016-0334-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Poonam Phalak
- Department of Chemical Engineering and Institute for Applied Life Sciences, University of Massachusetts, 240 Thatcher Way, Life Science Laboratories Building, Amherst, MA, 01003, USA
| | - Jin Chen
- Department of Chemical Engineering and Institute for Applied Life Sciences, University of Massachusetts, 240 Thatcher Way, Life Science Laboratories Building, Amherst, MA, 01003, USA
| | - Ross P Carlson
- Department of Chemical and Biological Engineering and Center for Biofilm Engineering, Montana State University, Bozeman, MT, 59717, USA
| | - Michael A Henson
- Department of Chemical Engineering and Institute for Applied Life Sciences, University of Massachusetts, 240 Thatcher Way, Life Science Laboratories Building, Amherst, MA, 01003, USA.
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In Situ Hydrogen Dynamics in a Hot Spring Microbial Mat during a Diel Cycle. Appl Environ Microbiol 2016; 82:4209-4217. [PMID: 27208140 DOI: 10.1128/aem.00710-16] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 04/29/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Microbes can produce molecular hydrogen (H2) via fermentation, dinitrogen fixation, or direct photolysis, yet the H2 dynamics in cyanobacterial communities has only been explored in a few natural systems and mostly in the laboratory. In this study, we investigated the diel in situ H2 dynamics in a hot spring microbial mat, where various ecotypes of unicellular cyanobacteria (Synechococcus sp.) are the only oxygenic phototrophs. In the evening, H2 accumulated rapidly after the onset of darkness, reaching peak values of up to 30 μmol H2 liter(-1) at about 1-mm depth below the mat surface, slowly decreasing to about 11 μmol H2 liter(-1) just before sunrise. Another pulse of H2 production, reaching a peak concentration of 46 μmol H2 liter(-1), was found in the early morning under dim light conditions too low to induce accumulation of O2 in the mat. The light stimulation of H2 accumulation indicated that nitrogenase activity was an important source of H2 during the morning. This is in accordance with earlier findings of a distinct early morning peak in N2 fixation and expression of Synechococcus nitrogenase genes in mat samples from the same location. Fermentation might have contributed to the formation of H2 during the night, where accumulation of other fermentation products lowered the pH in the mat to less than pH 6 compared to a spring source pH of 8.3. IMPORTANCE Hydrogen is a key intermediate in anaerobic metabolism, and with the development of a sulfide-insensitive microsensor for H2, it is now possible to study the microdistribution of H2 in stratified microbial communities such as the photosynthetic microbial mat investigated here. The ability to measure H2 profiles within the mat compared to previous measurements of H2 emission gives much more detailed information about the sources and sinks of H2 in such communities, and it was demonstrated that the high rates of H2 formation in the early morning when the mat was exposed to low light intensities might be explained by nitrogen fixation, where H2 is formed as a by-product.
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Oxidation of Molecular Hydrogen by a Chemolithoautotrophic Beggiatoa Strain. Appl Environ Microbiol 2016; 82:2527-36. [PMID: 26896131 PMCID: PMC4959497 DOI: 10.1128/aem.03818-15] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 02/10/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED A chemolithoautotrophic strain of the family Beggiatoaceae, Beggiatoa sp. strain 35Flor, was found to oxidize molecular hydrogen when grown in a medium with diffusional gradients of oxygen, sulfide, and hydrogen. Microsensor profiles and rate measurements suggested that the strain oxidized hydrogen aerobically when oxygen was available, while hydrogen consumption under anoxic conditions was presumably driven by sulfur respiration.Beggiatoa sp. 35Flor reached significantly higher biomass in hydrogen-supplemented oxygen-sulfide gradient media, but hydrogen did not support growth of the strain in the absence of reduced sulfur compounds. Nevertheless, hydrogen oxidation can provide Beggiatoa sp. 35Flor with energy for maintenance and assimilatory purposes and may support the disposal of internally stored sulfur to prevent physical damage resulting from excessive sulfur accumulation. Our knowledge about the exposure of natural populations of Beggiatoa ceae to hydrogen is very limited, but significant amounts of hydrogen could be provided by nitrogen fixation, fermentation, and geochemical processes in several of their typical habitats such as photosynthetic microbial mats and submarine sites of hydrothermal fluid flow. IMPORTANCE Reduced sulfur compounds are certainly the main electron donors for chemolithoautotrophic Beggiatoa ceae, but the traditional focus on this topic has left other possible inorganic electron donors largely unexplored. In this paper, we provide evidence that hydrogen oxidation has the potential to strengthen the ecophysiological plasticity of Beggiatoa ceaein several ways. Moreover, we show that hydrogen oxidation by members of this family can significantly influence biogeochemical gradients and therefore should be considered in environmental studies.
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Wong HL, Ahmed-Cox A, Burns BP. Molecular Ecology of Hypersaline Microbial Mats: Current Insights and New Directions. Microorganisms 2016; 4:microorganisms4010006. [PMID: 27681900 PMCID: PMC5029511 DOI: 10.3390/microorganisms4010006] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 12/08/2015] [Accepted: 12/15/2015] [Indexed: 11/17/2022] Open
Abstract
Microbial mats are unique geobiological ecosystems that form as a result of complex communities of microorganisms interacting with each other and their physical environment. Both the microorganisms present and the network of metabolic interactions govern ecosystem function therein. These systems are often found in a range of extreme environments, and those found in elevated salinity have been particularly well studied. The purpose of this review is to briefly describe the molecular ecology of select model hypersaline mat systems (Guerrero Negro, Shark Bay, S’Avall, and Kiritimati Atoll), and any potentially modulating effects caused by salinity to community structure. In addition, we discuss several emerging issues in the field (linking function to newly discovered phyla and microbial dark matter), which illustrate the changing paradigm that is seen as technology has rapidly advanced in the study of these extreme and evolutionally significant ecosystems.
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Affiliation(s)
- Hon Lun Wong
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney 2052, Australia.
- Australian Centre for Astrobiology, University of New South Wales, Sydney 2052, Australia.
| | - Aria Ahmed-Cox
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney 2052, Australia.
| | - Brendan Paul Burns
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney 2052, Australia.
- Australian Centre for Astrobiology, University of New South Wales, Sydney 2052, Australia.
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Wong HL, Smith DL, Visscher PT, Burns BP. Niche differentiation of bacterial communities at a millimeter scale in Shark Bay microbial mats. Sci Rep 2015; 5:15607. [PMID: 26499760 PMCID: PMC4620479 DOI: 10.1038/srep15607] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 09/28/2015] [Indexed: 02/01/2023] Open
Abstract
Modern microbial mats can provide key insights into early Earth ecosystems, and Shark Bay, Australia, holds one of the best examples of these systems. Identifying the spatial distribution of microorganisms with mat depth facilitates a greater understanding of specific niches and potentially novel microbial interactions. High throughput sequencing coupled with elemental analyses and biogeochemical measurements of two distinct mat types (smooth and pustular) at a millimeter scale were undertaken in the present study. A total of 8,263,982 16S rRNA gene sequences were obtained, which were affiliated to 58 bacterial and candidate phyla. The surface of both mats were dominated by Cyanobacteria, accompanied with known or putative members of Alphaproteobacteria and Bacteroidetes. The deeper anoxic layers of smooth mats were dominated by Chloroflexi, while Alphaproteobacteria dominated the lower layers of pustular mats. In situ microelectrode measurements revealed smooth mats have a steeper profile of O2 and H2S concentrations, as well as higher oxygen production, consumption, and sulfate reduction rates. Specific elements (Mo, Mg, Mn, Fe, V, P) could be correlated with specific mat types and putative phylogenetic groups. Models are proposed for these systems suggesting putative surface anoxic niches, differential nitrogen fixing niches, and those coupled with methane metabolism.
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Affiliation(s)
- Hon Lun Wong
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
- Australian Centre for Astrobiology, University of New South Wales Sydney, Australia
| | - Daniela-Lee Smith
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
- Australian Centre for Astrobiology, University of New South Wales Sydney, Australia
| | - Pieter T. Visscher
- Department of Marine Sciences, University of Connecticut, USA
- Australian Centre for Astrobiology, University of New South Wales Sydney, Australia
| | - Brendan P. Burns
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
- Australian Centre for Astrobiology, University of New South Wales Sydney, Australia
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Cyanobacterial reuse of extracellular organic carbon in microbial mats. ISME JOURNAL 2015; 10:1240-51. [PMID: 26495994 PMCID: PMC5029224 DOI: 10.1038/ismej.2015.180] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 08/21/2015] [Accepted: 09/02/2015] [Indexed: 11/09/2022]
Abstract
Cyanobacterial organic matter excretion is crucial to carbon cycling in many microbial communities, but the nature and bioavailability of this C depend on unknown physiological functions. Cyanobacteria-dominated hypersaline laminated mats are a useful model ecosystem for the study of C flow in complex communities, as they use photosynthesis to sustain a more or less closed system. Although such mats have a large C reservoir in the extracellular polymeric substances (EPSs), the production and degradation of organic carbon is not well defined. To identify extracellular processes in cyanobacterial mats, we examined mats collected from Elkhorn Slough (ES) at Monterey Bay, California, for glycosyl and protein composition of the EPS. We found a prevalence of simple glucose polysaccharides containing either α or β (1,4) linkages, indicating distinct sources of glucose with differing enzymatic accessibility. Using proteomics, we identified cyanobacterial extracellular enzymes, and also detected activities that indicate a capacity for EPS degradation. In a less complex system, we characterized the EPS of a cyanobacterial isolate from ES, ESFC-1, and found the extracellular composition of biofilms produced by this unicyanobacterial culture were similar to that of natural mats. By tracing isotopically labeled EPS into single cells of ESFC-1, we demonstrated rapid incorporation of extracellular-derived carbon. Taken together, these results indicate cyanobacteria reuse excess organic carbon, constituting a dynamic pool of extracellular resources in these mats.
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36
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Davison M, Hall E, Zare R, Bhaya D. Challenges of metagenomics and single-cell genomics approaches for exploring cyanobacterial diversity. PHOTOSYNTHESIS RESEARCH 2015; 126:135-146. [PMID: 25515769 DOI: 10.1007/s11120-014-0066-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 12/10/2014] [Indexed: 06/04/2023]
Abstract
Cyanobacteria have played a crucial role in the history of early earth and continue to be instrumental in shaping our planet, yet applications of cutting edge technology have not yet been widely used to explore cyanobacterial diversity. To provide adequate background, we briefly review current sequencing technologies and their innovative uses in genomics and metagenomics. Next, we focus on current cell capture technologies and the challenges of using them with cyanobacteria. We illustrate the utility in coupling breakthroughs in DNA amplification with cell capture platforms, with an example of microfluidic isolation and subsequent targeted amplicon sequencing from individual terrestrial thermophilic cyanobacteria. Single cells of thermophilic, unicellular Synechococcus sp. JA-2-3-B'a(2-13) (Syn OS-B') were sorted in a microfluidic device, lysed, and subjected to whole genome amplification by multiple displacement amplification. We amplified regions from specific CRISPR spacer arrays, which are known to be highly diverse, contain semi-palindromic repeats which form secondary structure, and can be difficult to amplify. Cell capture, lysis, and genome amplification on a microfluidic device have been optimized, setting a stage for further investigations of individual cyanobacterial cells isolated directly from natural populations.
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Affiliation(s)
- Michelle Davison
- Department of Plant Biology, Carnegie Institution of Science, 260 Panama Street, Stanford, CA, 94305, USA.
| | - Eric Hall
- SRI International, 333 Ravenswood Ave, Menlo Park, CA, 94025, USA
| | - Richard Zare
- Department of Chemistry, Stanford University, 333 Campus Drive Mudd Building, Room 121, Stanford, CA, 94305-4401, USA
| | - Devaki Bhaya
- Department of Plant Biology, Carnegie Institution of Science, 260 Panama Street, Stanford, CA, 94305, USA
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Brady AL, Sharp CE, Grasby SE, Dunfield PF. Anaerobic carboxydotrophic bacteria in geothermal springs identified using stable isotope probing. Front Microbiol 2015; 6:897. [PMID: 26388850 PMCID: PMC4555085 DOI: 10.3389/fmicb.2015.00897] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Accepted: 08/17/2015] [Indexed: 12/25/2022] Open
Abstract
Carbon monoxide (CO) is a potential energy and carbon source for thermophilic bacteria in geothermal environments. Geothermal sites ranging in temperature from 45 to 65°C were investigated for the presence and activity of anaerobic CO-oxidizing bacteria. Anaerobic CO oxidation potentials were measured at up to 48.9 μmoles CO g−1 (wet weight) day−1 within five selected sites. Active anaerobic carboxydotrophic bacteria were identified using 13CO DNA stable isotope probing (SIP) combined with pyrosequencing of 16S rRNA genes amplified from labeled DNA. Bacterial communities identified in heavy DNA fractions were predominated by Firmicutes, which comprised up to 95% of all sequences in 13CO incubations. The predominant bacteria that assimilated 13C derived from CO were closely related (>98% 16S rRNA gene sequence identity) to genera of known carboxydotrophs including Thermincola, Desulfotomaculum, Thermolithobacter, and Carboxydocella, although a few species with lower similarity to known bacteria were also found that may represent previously unconfirmed CO-oxidizers. While the distribution was variable, many of the same OTUs were identified across sample sites from different temperature regimes. These results show that bacteria capable of using CO as a carbon source are common in geothermal springs, and that thermophilic carboxydotrophs are probably already quite well known from cultivation studies.
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Affiliation(s)
- Allyson L Brady
- Department of Biological Sciences, University of Calgary Calgary, AB, Canada
| | - Christine E Sharp
- Department of Biological Sciences, University of Calgary Calgary, AB, Canada
| | | | - Peter F Dunfield
- Department of Biological Sciences, University of Calgary Calgary, AB, Canada
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Nielsen M, Revsbech NP, Kühl M. Microsensor measurements of hydrogen gas dynamics in cyanobacterial microbial mats. Front Microbiol 2015; 6:726. [PMID: 26257714 PMCID: PMC4508582 DOI: 10.3389/fmicb.2015.00726] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 07/02/2015] [Indexed: 11/16/2022] Open
Abstract
We used a novel amperometric microsensor for measuring hydrogen gas production and consumption at high spatio-temporal resolution in cyanobacterial biofilms and mats dominated by non-heterocystous filamentous cyanobacteria (Microcoleus chtonoplastes and Oscillatoria sp.). The new microsensor is based on the use of an organic electrolyte and a stable internal reference system and can be equipped with a chemical sulfide trap in the measuring tip; it exhibits very stable and sulfide-insensitive measuring signals and a high sensitivity (1.5–5 pA per μmol L-1 H2). Hydrogen gas measurements were done in combination with microsensor measurements of scalar irradiance, O2, pH, and H2S and showed a pronounced H2 accumulation (of up to 8–10% H2 saturation) within the upper mm of cyanobacterial mats after onset of darkness and O2 depletion. The peak concentration of H2 increased with the irradiance level prior to darkening. After an initial build-up over the first 1–2 h in darkness, H2 was depleted over several hours due to efflux to the overlaying water, and due to biogeochemical processes in the uppermost oxic layers and the anoxic layers of the mats. Depletion could be prevented by addition of molybdate pointing to sulfate reduction as a major sink for H2. Immediately after onset of illumination, a short burst of presumably photo-produced H2 due to direct biophotolysis was observed in the illuminated but anoxic mat layers. As soon as O2 from photosynthesis started to accumulate, the H2 was consumed rapidly and production ceased. Our data give detailed insights into the microscale distribution and dynamics of H2 in cyanobacterial biofilms and mats, and further support that cyanobacterial H2 production can play a significant role in fueling anaerobic processes like e.g., sulfate reduction or anoxygenic photosynthesis in microbial mats.
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Affiliation(s)
- Michael Nielsen
- Section of Microbiology, Department of Bioscience, Aarhus University Aarhus, Denmark
| | - Niels P Revsbech
- Section of Microbiology, Department of Bioscience, Aarhus University Aarhus, Denmark
| | - Michael Kühl
- Marine Biological Section, Department of Biology, University of Copenhagen Helsingør, Denmark ; Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, Ultimo NSW, Australia
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Birgel D, Meister P, Lundberg R, Horath TD, Bontognali TRR, Bahniuk AM, de Rezende CE, Vasconcelos C, McKenzie JA. Methanogenesis produces strong 13C enrichment in stromatolites of Lagoa Salgada, Brazil: a modern analogue for Palaeo-/Neoproterozoic stromatolites? GEOBIOLOGY 2015; 13:245-266. [PMID: 25773379 DOI: 10.1111/gbi.12130] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Accepted: 01/26/2015] [Indexed: 06/04/2023]
Abstract
Holocene stromatolites characterized by unusually positive inorganic δ(13) CPDB values (i.e. up to +16‰) are present in Lagoa Salgada, a seasonally brackish to hypersaline lagoon near Rio de Janeiro (Brazil). Such positive values cannot be explained by phototrophic fixation of CO2 alone, and they suggest that methanogenesis was a dominating process during the growth of the stromatolites. Indeed, up to 5 mm methane was measured in the porewater. The archaeal membrane lipid archaeol showing δ(13) C values between -15 and 0‰ suggests that archaea are present and producing methane in the modern lagoon sediment. Moreover, (13) C-depleted hopanoids diplopterol and 3β-methylated C32 17β(H),21β(H)-hopanoic acid (both -40‰) are preserved in lagoon sediments and are most likely derived from aerobic methanotrophic bacteria thriving in the methane-enriched water column. Loss of isotopically light methane through the water column would explain the residual (13) C-enriched pool of dissolved inorganic carbon from where the carbonate constituting the stromatolites precipitated. The predominance of methanogenic archaea in the lagoon is most likely a result of sulphate limitation, suppressing the activity of sulphate-reducing bacteria under brackish conditions in a seasonally humid tropical environment. Indeed, sulphate-reduction activity is very low in the modern sediments. In absence of an efficient carbonate-inducing metabolic process, we propose that stromatolite formation in Lagoa Salgada was abiotically induced, while the (13) C-enriched organic and inorganic carbon pools are due to methanogenesis. Unusually, (13) C-enriched stromatolitic deposits also appear in the geological record of prolonged periods in the Palaeo- and Neoproterozoic. Lagoa Salgada represents a possible modern analogue to conditions that may have been widespread in the Proterozoic, at times when low sulphate concentrations in sea water allowed methanogens to prevail over sulphate-reducing bacteria.
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Affiliation(s)
- D Birgel
- Department of Geodynamics and Sedimentology, University of Vienna, Vienna, Austria
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Murphy TE, Pilorz S, Prufert-Bebout L, Bebout B. A Novel Microsensor for Measuring Angular Distribution of Radiative Intensity. Photochem Photobiol 2015; 91:862-8. [PMID: 25763775 DOI: 10.1111/php.12452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 03/07/2015] [Indexed: 11/28/2022]
Abstract
This article presents the design, construction and characterization of a novel type of light probe for measuring the angular radiance distribution of light fields. The differential acceptance angle (DAA) probe can resolve the directionality of a light field in environments with steep light gradients, such as microbial mats, without the need to remove, reorient, and reinsert the probe, a clear advantage over prior techniques. The probe consists of an inner irradiance sensor inside a concentric, moveable light-absorbing sheath. The radiative intensity in a specific zenith direction can be calculated by comparing the irradiance onto the sensor at different acceptance angles. We used this probe to measure the angular radiance distribution of two sample light fields, and observed good agreement with a conventional radiance probe. The DAA probe will aid researchers in understanding light transfer physics in dense microbial communities and expedite validation of numerical radiative transfer models for these environments.
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Affiliation(s)
| | | | | | - Brad Bebout
- NASA Ames Research Center, Moffett Field, CA
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Voorhies AA, Eisenlord SD, Marcus DN, Duhaime MB, Biddanda BA, Cavalcoli JD, Dick GJ. Ecological and genetic interactions between cyanobacteria and viruses in a low-oxygen mat community inferred through metagenomics and metatranscriptomics. Environ Microbiol 2015; 18:358-71. [DOI: 10.1111/1462-2920.12756] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 12/15/2014] [Indexed: 12/26/2022]
Affiliation(s)
- Alexander A. Voorhies
- Department of Earth and Environmental Sciences; University of Michigan; Ann Arbor MI 48109 USA
| | - Sarah D. Eisenlord
- School of Natural Resources and Environment; University of Michigan; Ann Arbor MI 48109 USA
| | - Daniel N. Marcus
- Department of Earth and Environmental Sciences; University of Michigan; Ann Arbor MI 48109 USA
| | - Melissa B. Duhaime
- Department of Ecology and Evolutionary Biology; University of Michigan; Ann Arbor MI 48109 USA
| | - Bopaiah A. Biddanda
- Annis Water Resources Institute; Grand Valley State University; Muskegon MI 49441 USA
| | - James D. Cavalcoli
- Department of Computational Medicine and Bioinformatics; University of Michigan; Ann Arbor MI 48109 USA
| | - Gregory J. Dick
- Department of Earth and Environmental Sciences; University of Michigan; Ann Arbor MI 48109 USA
- Department of Ecology and Evolutionary Biology; University of Michigan; Ann Arbor MI 48109 USA
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Hoffmann D, Maldonado J, Wojciechowski MF, Garcia-Pichel F. Hydrogen export from intertidal cyanobacterial mats: sources, fluxes and the influence of community composition. Environ Microbiol 2015; 17:3738-53. [DOI: 10.1111/1462-2920.12769] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 12/23/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Dörte Hoffmann
- School of Life Sciences; Arizona State University; Tempe AZ 85287-4501 USA
| | - Juan Maldonado
- School of Life Sciences; Arizona State University; Tempe AZ 85287-4501 USA
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García-Maldonado JQ, Bebout BM, Everroad RC, López-Cortés A. Evidence of novel phylogenetic lineages of methanogenic archaea from hypersaline microbial mats. MICROBIAL ECOLOGY 2015; 69:106-117. [PMID: 25108574 DOI: 10.1007/s00248-014-0473-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 07/25/2014] [Indexed: 06/03/2023]
Abstract
Methanogenesis in hypersaline and high-sulfate environments is typically dominated by methylotrophic methanogens because sulfate reduction is thermodynamically favored over hydrogenotrophic methanogenesis in these environments. We characterized the community composition of methanogenic archaea in both unmanipulated and incubated microbial mats from different hypersaline environments in Baja California Sur, Mexico. Clone libraries of methyl coenzyme-M reductase (mcrA) sequences and DGGE band patterns of 16S rRNA and mcrA sequences showed that the methanogen community in these microbial mats is dominated by methylotrophic methanogens of the genus Methanohalophilus. However, phylogenetic analyses of mcrA sequences from these mats also revealed two new lineages corresponding to putative hydrogenotrophic methanogens related with the strictly hydrogenotrophic order Methanomicrobiales. Stimulated methane production under decreased salinity and sulfate concentrations also suggested the presence of hydrogenotrophic methanogens in these samples. The relative abundance of mcrA gene and transcripts, estimated by SYBR green I qPCR assays, suggested the activity of different phylogenetic groups of methanogens, including the two novel clusters, in unmanipulated samples of hypersaline microbial mats. Using geochemical and molecular approaches, we show that substrate limitation and values of salinity and sulfate higher than 3 % and 25 mM (respectively) are potential environmental constraints for methanogenesis in these environments. Microcosm experiments with modifications of salinity and sulfate concentrations and TMA addition showed that upper salt and sulfate concentrations for occurrence of methylotrophic methanogenesis were 28 % and 263 mM, respectively. This study provides phylogenetic information about uncultivated and undescribed methanogenic archaea from hypersaline environments.
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Affiliation(s)
- José Q García-Maldonado
- Laboratorio de Geomicrobiología y Biotecnología, Centro de Investigaciones Biológicas del Noroeste, La Paz, BCS, Mexico
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Kothari A, Parameswaran P, Garcia-Pichel F. Powerful fermentative hydrogen evolution of photosynthate in the cyanobacterium Lyngbya aestuarii BL J mediated by a bidirectional hydrogenase. Front Microbiol 2014; 5:680. [PMID: 25540642 PMCID: PMC4261827 DOI: 10.3389/fmicb.2014.00680] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 11/20/2014] [Indexed: 11/25/2022] Open
Abstract
Cyanobacteria are considered good models for biohydrogen production because they are relatively simple organisms with a demonstrable ability to generate H2 under certain physiological conditions. However, most produce only little H2, revert readily to H2 consumption, and suffer from hydrogenase sensitivity to O2. Strains of the cyanobacteria Lyngbya aestuarii and Microcoleus chthonoplastes obtained from marine intertidal cyanobacterial mats were recently found to display much better H2 production potential. Because of their ecological origin in environments that become quickly anoxic in the dark, we hypothesized that this differential ability may have evolved to serve a role in the fermentation of the photosynthate. Here we show that, when forced to ferment internal substrate, these cyanobacteria display desirable characteristics of physiological H2 production. Among them, the strain L. aestuarii BL J had the fastest specific rates and attained the highest H2 concentrations during fermentation of photosynthate, which proceeded via a mixed acid fermentation pathway to yield acetate, ethanol, lactate, H2, CO2, and pyruvate. Contrary to expectations, the H2 yield per mole of glucose was only average compared to that of other cyanobacteria. Thermodynamic analyses point to the use of electron donors more electronegative than NAD(P)H in Lyngbya hydrogenases as the basis for its strong H2 production ability. In any event, the high specific rates and H2 concentrations coupled with the lack of reversibility of the enzyme, at the expense of internal, photosynthetically generated reductants, makes L. aestuarii BL J and/or its enzymes, a potentially feasible platform for large-scale H2 production.
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Affiliation(s)
- Ankita Kothari
- School of Life Sciences, Arizona State University Tempe, AZ, USA
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Houghton J, Fike D, Druschel G, Orphan V, Hoehler TM, Des Marais DJ. Spatial variability in photosynthetic and heterotrophic activity drives localized δ13C org fluctuations and carbonate precipitation in hypersaline microbial mats. GEOBIOLOGY 2014; 12:557-574. [PMID: 25312537 DOI: 10.1111/gbi.12113] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 08/30/2014] [Indexed: 06/04/2023]
Abstract
Modern laminated photosynthetic microbial mats are ideal environments to study how microbial activity creates and modifies carbon and sulfur isotopic signatures prior to lithification. Laminated microbial mats from a hypersaline lagoon (Guerrero Negro, Baja California, Mexico) maintained in a flume in a greenhouse at NASA Ames Research Center were sampled for δ(13) C of organic material and carbonate to assess the impact of carbon fixation (e.g., photosynthesis) and decomposition (e.g., bacterial respiration) on δ(13) C signatures. In the photic zone, the δ(13) C org signature records a complex relationship between the activities of cyanobacteria under variable conditions of CO2 limitation with a significant contribution from green sulfur bacteria using the reductive TCA cycle for carbon fixation. Carbonate is present in some layers of the mat, associated with high concentrations of bacteriochlorophyll e (characteristic of green sulfur bacteria) and exhibits δ(13) C signatures similar to DIC in the overlying water column (-2.0‰), with small but variable decreases consistent with localized heterotrophic activity from sulfate-reducing bacteria (SRB). Model results indicate respiration rates in the upper 12 mm of the mat alter in situ pH and HCO3- concentrations to create both phototrophic CO2 limitation and carbonate supersaturation, leading to local precipitation of carbonate minerals. The measured activity of SRB with depth suggests they variably contribute to decomposition in the mat dependent on organic substrate concentrations. Millimeter-scale variability in the δ(13) C org signature beneath the photic zone in the mat is a result of shifting dominance between cyanobacteria and green sulfur bacteria with the aggregate signature overprinted by heterotrophic reworking by SRB and methanogens. These observations highlight the impact of sedimentary microbial processes on δ(13) C org signatures; these processes need to be considered when attempting to relate observed isotopic signatures in ancient sedimentary strata to conditions in the overlying water column at the time of deposition and associated inferences about carbon cycling.
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Affiliation(s)
- J Houghton
- Department of Earth and Planetary Sciences, Washington University, St. Louis, MO, USA
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Koch H, Galushko A, Albertsen M, Schintlmeister A, Gruber-Dorninger C, Lücker S, Pelletier E, Le Paslier D, Spieck E, Richter A, Nielsen PH, Wagner M, Daims H. Growth of nitrite-oxidizing bacteria by aerobic hydrogen oxidation. Science 2014; 345:1052-4. [PMID: 25170152 DOI: 10.1126/science.1256985] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The bacterial oxidation of nitrite to nitrate is a key process of the biogeochemical nitrogen cycle. Nitrite-oxidizing bacteria are considered a highly specialized functional group, which depends on the supply of nitrite from other microorganisms and whose distribution strictly correlates with nitrification in the environment and in wastewater treatment plants. On the basis of genomics, physiological experiments, and single-cell analyses, we show that Nitrospira moscoviensis, which represents a widely distributed lineage of nitrite-oxidizing bacteria, has the genetic inventory to utilize hydrogen (H2) as an alternative energy source for aerobic respiration and grows on H2 without nitrite. CO2 fixation occurred with H2 as the sole electron donor. Our results demonstrate a chemolithoautotrophic lifestyle of nitrite-oxidizing bacteria outside the nitrogen cycle, suggesting greater ecological flexibility than previously assumed.
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Affiliation(s)
- Hanna Koch
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, 1090 Vienna, Austria
| | - Alexander Galushko
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, 1090 Vienna, Austria
| | - Mads Albertsen
- Center for Microbial Communities, Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, 9000 Aalborg, Denmark
| | - Arno Schintlmeister
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, 1090 Vienna, Austria. Large Instrument Facility for Advanced Isotope Research, University of Vienna, 1090 Vienna, Austria
| | - Christiane Gruber-Dorninger
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, 1090 Vienna, Austria
| | - Sebastian Lücker
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, 1090 Vienna, Austria
| | - Eric Pelletier
- Commissariat à l'Energie Atomique, Direction des Sciences du Vivant, Institut de génomique, Genoscope, 91057 Evry, France. Centre National de la Recherche Scientifique, UMR8030, 91057 Evry, France. Université d'Evry Val d'Essonne, 91057 Evry, France
| | - Denis Le Paslier
- Commissariat à l'Energie Atomique, Direction des Sciences du Vivant, Institut de génomique, Genoscope, 91057 Evry, France. Centre National de la Recherche Scientifique, UMR8030, 91057 Evry, France. Université d'Evry Val d'Essonne, 91057 Evry, France
| | - Eva Spieck
- Biozentrum Klein Flottbek, Microbiology and Biotechnology, University of Hamburg, 22609 Hamburg, Germany
| | - Andreas Richter
- Department of Microbiology and Ecosystem Science, Division of Terrestrial Ecosystem Research, University of Vienna, 1090 Vienna, Austria
| | - Per H Nielsen
- Center for Microbial Communities, Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, 9000 Aalborg, Denmark
| | - Michael Wagner
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, 1090 Vienna, Austria
| | - Holger Daims
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, 1090 Vienna, Austria.
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Burow LC, Woebken D, Marshall IPG, Singer SW, Pett-Ridge J, Prufert-Bebout L, Spormann AM, Bebout BM, Weber PK, Hoehler TM. Identification of Desulfobacterales as primary hydrogenotrophs in a complex microbial mat community. GEOBIOLOGY 2014; 12:221-230. [PMID: 24730641 DOI: 10.1111/gbi.12080] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 01/22/2014] [Indexed: 06/03/2023]
Abstract
Hypersaline microbial mats have been shown to produce significant quantities of H2 under dark, anoxic conditions via cyanobacterial fermentation. This flux of a widely accessible microbial substrate has potential to significantly influence the ecology of the mat, and any consumption will affect the net efflux of H2 that might otherwise be captured as a resource. Here, we focus on H2 consumption in a microbial mat from Elkhorn Slough, California, USA, for which H2 production has been previously characterized. Active biologic H2 consumption in this mat is indicated by a significant time-dependent decrease in added H2 compared with a killed control. Inhibition of sulfate reduction, as indicated by a decrease in hydrogen sulfide production relative to controls, resulted in a significant increase in H2 efflux, suggesting that sulfate-reducing bacteria (SRB) are important hydrogenotrophs. Low methane efflux under these same conditions indicated that methanogens are likely not important hydrogenotrophs. Analyses of genes and transcripts that encode for rRNA or dissimilatory sulfite reductase, using both PCR-dependent and PCR-independent metatranscriptomic sequencing methods, demonstrated that Desulfobacterales are the dominant, active SRB in the upper, H2-producing layer of the mat (0-2 mm). This hypothesis was further supported by the identification of transcripts encoding hydrogenases derived from Desulfobacterales capable of H2 oxidation. Analysis of molecular data provided no evidence for the activity of hydrogenotrophic methanogens. The combined biogeochemical and molecular data strongly indicate that SRB belonging to the Desulfobacterales are the quantitatively important hydrogenotrophs in the Elkhorn Slough mat.
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Affiliation(s)
- L C Burow
- Departments of Chemical, Civil and Environmental Engineering, Stanford University, Stanford, CA, USA; Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, USA
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Lee JZ, Burow LC, Woebken D, Everroad RC, Kubo MD, Spormann AM, Weber PK, Pett-Ridge J, Bebout BM, Hoehler TM. Fermentation couples Chloroflexi and sulfate-reducing bacteria to Cyanobacteria in hypersaline microbial mats. Front Microbiol 2014; 5:61. [PMID: 24616716 PMCID: PMC3935151 DOI: 10.3389/fmicb.2014.00061] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 01/30/2014] [Indexed: 11/17/2022] Open
Abstract
Past studies of hydrogen cycling in hypersaline microbial mats have shown an active nighttime cycle, with production largely from Cyanobacteria and consumption from sulfate-reducing bacteria (SRB). However, the mechanisms and magnitude of hydrogen cycling have not been extensively studied. Two mats types near Guerrero Negro, Mexico-permanently submerged Microcoleus microbial mat (GN-S), and intertidal Lyngbya microbial mat (GN-I)-were used in microcosm diel manipulation experiments with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), molybdate, ammonium addition, and physical disruption to understand the processes responsible for hydrogen cycling between mat microbes. Across microcosms, H2 production occurred under dark anoxic conditions with simultaneous production of a suite of organic acids. H2 production was not significantly affected by inhibition of nitrogen fixation, but rather appears to result from constitutive fermentation of photosynthetic storage products by oxygenic phototrophs. Comparison to accumulated glycogen and to CO2 flux indicated that, in the GN-I mat, fermentation released almost all of the carbon fixed via photosynthesis during the preceding day, primarily as organic acids. Across mats, although oxygenic and anoxygenic phototrophs were detected, cyanobacterial [NiFe]-hydrogenase transcripts predominated. Molybdate inhibition experiments indicated that SRBs from a wide distribution of DsrA phylotypes were responsible for H2 consumption. Incubation with (13)C-acetate and NanoSIMS (secondary ion mass-spectrometry) indicated higher uptake in both Chloroflexi and SRBs relative to other filamentous bacteria. These manipulations and diel incubations confirm that Cyanobacteria were the main fermenters in Guerrero Negro mats and that the net flux of nighttime fermentation byproducts (not only hydrogen) was largely regulated by the interplay between Cyanobacteria, SRBs, and Chloroflexi.
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Affiliation(s)
- Jackson Z. Lee
- Exobiology Branch, NASA Ames Research CenterMoffett Field, CA, USA
- Bay Area Environmental Research InstituteSonoma, CA, USA
| | - Luke C. Burow
- Exobiology Branch, NASA Ames Research CenterMoffett Field, CA, USA
- Departments of Civil and Environmental Engineering, and Chemical Engineering, Stanford UniversityStanford, CA, USA
| | - Dagmar Woebken
- Exobiology Branch, NASA Ames Research CenterMoffett Field, CA, USA
- Departments of Civil and Environmental Engineering, and Chemical Engineering, Stanford UniversityStanford, CA, USA
| | | | - Mike D. Kubo
- Exobiology Branch, NASA Ames Research CenterMoffett Field, CA, USA
- The SETI InstituteMountain View, CA, USA
| | - Alfred M. Spormann
- Departments of Civil and Environmental Engineering, and Chemical Engineering, Stanford UniversityStanford, CA, USA
| | - Peter K. Weber
- Lawrence Livermore National Lab, Chemical Sciences DivisionLivermore, CA, USA
| | - Jennifer Pett-Ridge
- Lawrence Livermore National Lab, Chemical Sciences DivisionLivermore, CA, USA
| | - Brad M. Bebout
- Exobiology Branch, NASA Ames Research CenterMoffett Field, CA, USA
| | - Tori M. Hoehler
- Exobiology Branch, NASA Ames Research CenterMoffett Field, CA, USA
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50
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D'Adamo S, Jinkerson RE, Boyd ES, Brown SL, Baxter BK, Peters JW, Posewitz MC. Evolutionary and biotechnological implications of robust hydrogenase activity in halophilic strains of Tetraselmis. PLoS One 2014; 9:e85812. [PMID: 24465722 PMCID: PMC3897525 DOI: 10.1371/journal.pone.0085812] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 12/02/2013] [Indexed: 11/19/2022] Open
Abstract
Although significant advances in H2 photoproduction have recently been realized in fresh water algae (e.g. Chlamydomonas reinhardtii), relatively few studies have focused on H2 production and hydrogenase adaptations in marine or halophilic algae. Salt water organisms likely offer several advantages for biotechnological H2 production due to the global abundance of salt water, decreased H2 and O2 solubility in saline and hypersaline systems, and the ability of extracellular NaCl levels to influence metabolism. We screened unialgal isolates obtained from hypersaline ecosystems in the southwest United States and identified two distinct halophilic strains of the genus Tetraselmis (GSL1 and QNM1) that exhibit both robust fermentative and photo H2-production activities. The influence of salinity (3.5%, 5.5% and 7.0% w/v NaCl) on H2 production was examined during anoxic acclimation, with the greatest in vivo H2-production rates observed at 7.0% NaCl. These Tetraselmis strains maintain robust hydrogenase activity even after 24 h of anoxic acclimation and show increased hydrogenase activity relative to C. reinhardtii after extended anoxia. Transcriptional analysis of Tetraselmis GSL1 enabled sequencing of the cDNA encoding the FeFe-hydrogenase structural enzyme (HYDA) and its maturation proteins (HYDE, HYDEF and HYDG). In contrast to freshwater Chlorophyceae, the halophilic Tetraselmis GSL1 strain likely encodes a single HYDA and two copies of HYDE, one of which is fused to HYDF. Phylogenetic analyses of HYDA and concatenated HYDA, HYDE, HYDF and HYDG in Tetraselmis GSL1 fill existing knowledge gaps in the evolution of algal hydrogenases and indicate that the algal hydrogenases sequenced to date are derived from a common ancestor. This is consistent with recent hypotheses that suggest fermentative metabolism in the majority of eukaryotes is derived from a common base set of enzymes that emerged early in eukaryotic evolution with subsequent losses in some organisms.
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Affiliation(s)
- Sarah D'Adamo
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, Colorado, United States of America
| | - Robert E. Jinkerson
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, Colorado, United States of America
| | - Eric S. Boyd
- Department of Microbiology and the Thermal Biology Institute, Montana State University, Bozeman, Montana, United States of America
| | - Susan L. Brown
- Center for Marine Microbial Ecology and Diversity, University of Hawaii, Honolulu, Hawaii, United States of America
| | - Bonnie K. Baxter
- Department of Biology and the Great Salt Lake Institute, Westminster College, Salt Lake City, Utah, United States of America
| | - John W. Peters
- Department of Microbiology and the Thermal Biology Institute, Montana State University, Bozeman, Montana, United States of America
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, United States of America
| | - Matthew C. Posewitz
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, Colorado, United States of America
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