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The Oligosaccharyltransferase AglB Supports Surface-Associated Growth and Iron Oxidation in Methanococcus maripaludis. Appl Environ Microbiol 2021; 87:e0099521. [PMID: 34132588 DOI: 10.1128/aem.00995-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Most microbial organisms grow as surface-attached communities known as biofilms. However, the mechanisms whereby methanogenic archaea grow attached to surfaces have remained understudied. Here, we show that the oligosaccharyltransferase AglB is essential for growth of Methanococcus maripaludis strain JJ on glass or metal surfaces. AglB glycosylates several cellular structures, such as pili, archaella, and the cell surface layer (S-layer). We show that the S-layer of strain JJ, but not strain S2, is a glycoprotein, that only strain JJ was capable of growth on surfaces, and that deletion of aglB blocked S-layer glycosylation and abolished surface-associated growth. A strain JJ mutant lacking structural components of the type IV-like pilus did not have a growth defect under any conditions tested, while a mutant lacking the preflagellin peptidase (ΔflaK) was defective for surface growth only when formate was provided as the sole electron donor. Finally, for strains that are capable of Fe0 oxidation, we show that deletion of aglB decreases the rate of anaerobic Fe0 oxidation, presumably due to decreased association of biomass with the Fe0 surface. Together, these data provide an initial characterization of surface-associated growth in a member of the methanogenic archaea. IMPORTANCE Methanogenic archaea are responsible for producing the majority of methane on Earth and catalyze the terminal reactions in the degradation of organic matter in anoxic environments. Methanogens often grow as biofilms associated with surfaces or partner organisms; however, the molecular details of surface-associated growth remain uncharacterized. We have found evidence that glycosylation of the cell surface layer is essential for growth of M. maripaludis on surfaces and can enhance rates of anaerobic iron corrosion. These results provide insight into the physiology of surface-associated methanogenic organisms and highlight the importance of surface association for anaerobic iron corrosion.
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Gao K, Lu Y. Putative Extracellular Electron Transfer in Methanogenic Archaea. Front Microbiol 2021; 12:611739. [PMID: 33828536 PMCID: PMC8019784 DOI: 10.3389/fmicb.2021.611739] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 03/03/2021] [Indexed: 11/14/2022] Open
Abstract
It has been suggested that a few methanogens are capable of extracellular electron transfers. For instance, Methanosarcina barkeri can directly capture electrons from the coexisting microbial cells of other species. Methanothrix harundinacea and Methanosarcina horonobensis retrieve electrons from Geobacter metallireducens via direct interspecies electron transfer (DIET). Recently, Methanobacterium, designated strain YSL, has been found to grow via DIET in the co-culture with Geobacter metallireducens. Methanosarcina acetivorans can perform anaerobic methane oxidation and respiratory growth relying on Fe(III) reduction through the extracellular electron transfer. Methanosarcina mazei is capable of electromethanogenesis under the conditions where electron-transfer mediators like H2 or formate are limited. The membrane-bound multiheme c-type cytochromes (MHC) and electrically-conductive cellular appendages have been assumed to mediate the extracellular electron transfer in bacteria like Geobacter and Shewanella species. These molecules or structures are rare but have been recently identified in a few methanogens. Here, we review the current state of knowledge for the putative extracellular electron transfers in methanogens and highlight the opportunities and challenges for future research.
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Affiliation(s)
- Kailin Gao
- College of Urban and Environmental Sciences, Peking University, Beijing, China
| | - Yahai Lu
- College of Urban and Environmental Sciences, Peking University, Beijing, China
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Baltic Sea methanogens compete with acetogens for electrons from metallic iron. ISME JOURNAL 2019; 13:3011-3023. [PMID: 31444483 PMCID: PMC6864099 DOI: 10.1038/s41396-019-0490-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 07/17/2019] [Accepted: 08/02/2019] [Indexed: 01/05/2023]
Abstract
Microbially induced corrosion of metallic iron (Fe0)-containing structures is an environmental and economic hazard. Methanogens are abundant in low-sulfide environments and yet their specific role in Fe0 corrosion is poorly understood. In this study, Sporomusa and Methanosarcina dominated enrichments from Baltic Sea methanogenic sediments that were established with Fe0 as the sole electron donor and CO2 as the electron acceptor. The Baltic-Sporomusa was phylogenetically affiliated to the electroactive acetogen S. silvacetica. Baltic-Sporomusa adjusted rapidly to growth on H2. On Fe0, spent filtrate enhanced growth of this acetogen suggesting that it was using endogenous enzymes to retrieve electrons and produce acetate. Previous studies have proposed that acetate produced by acetogens can feed commensal acetoclastic methanogens such as Methanosarcina. However, Baltic-methanogens could not generate methane from acetate, plus the decrease or absence of acetogens stimulated their growth. The decrease in numbers of Sporomusa was concurrent with an upsurge in Methanosarcina and increased methane production, suggesting that methanogens compete with acetogens for electrons from Fe0. Furthermore, Baltic-methanogens were unable to use H2 (1.5 atm) for methanogenesis and were inhibited by spent filtrate additions, indicating that enzymatically produced H2 is not a favorable electron donor. We hypothesize that Baltic-methanogens retrieve electrons from Fe0 via a yet enigmatic direct electron uptake mechanism.
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Nadeau J, Lindensmith C, Deming JW, Fernandez VI, Stocker R. Microbial Morphology and Motility as Biosignatures for Outer Planet Missions. ASTROBIOLOGY 2016; 16:755-774. [PMID: 27552160 PMCID: PMC5069736 DOI: 10.1089/ast.2015.1376] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 06/13/2016] [Indexed: 05/23/2023]
Abstract
Meaningful motion is an unambiguous biosignature, but because life in the Solar System is most likely to be microbial, the question is whether such motion may be detected effectively on the micrometer scale. Recent results on microbial motility in various Earth environments have provided insight into the physics and biology that determine whether and how microorganisms as small as bacteria and archaea swim, under which conditions, and at which speeds. These discoveries have not yet been reviewed in an astrobiological context. This paper discusses these findings in the context of Earth analog environments and environments expected to be encountered in the outer Solar System, particularly the jovian and saturnian moons. We also review the imaging technologies capable of recording motility of submicrometer-sized organisms and discuss how an instrument would interface with several types of sample-collection strategies. Key Words: In situ measurement-Biosignatures-Microbiology-Europa-Ice. Astrobiology 16, 755-774.
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Affiliation(s)
- Jay Nadeau
- 1 GALCIT, California Institute of Technology , Pasadena, California
| | - Chris Lindensmith
- 2 Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California
| | - Jody W Deming
- 3 Department of Biological Oceanography, University of Washington , Seattle, Washington
| | - Vicente I Fernandez
- 4 Department of Civil and Environmental Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts
| | - Roman Stocker
- 4 Department of Civil and Environmental Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts
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Bell TAS, Prithiviraj B, Wahlen BD, Fields MW, Peyton BM. A Lipid-Accumulating Alga Maintains Growth in Outdoor, Alkaliphilic Raceway Pond with Mixed Microbial Communities. Front Microbiol 2016; 6:1480. [PMID: 26779138 PMCID: PMC4703792 DOI: 10.3389/fmicb.2015.01480] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Accepted: 12/08/2015] [Indexed: 11/13/2022] Open
Abstract
Algal biofuels and valuable co-products are being produced in both open and closed cultivation systems. Growing algae in open pond systems may be a more economical alternative, but this approach allows environmental microorganisms to colonize the pond and potentially infect or outcompete the algal "crop." In this study, we monitored the microbial community of an outdoor, open raceway pond inoculated with a high lipid-producing alkaliphilic alga, Chlorella vulgaris BA050. The strain C. vulgaris BA050 was previously isolated from Soap Lake, Washington, a system characterized by a high pH (∼9.8). An outdoor raceway pond (200 L) was inoculated with C. vulgaris and monitored for 10 days and then the culture was transferred to a 2,000 L raceway pond and cultivated for an additional 6 days. Community DNA samples were collected over the 16-day period in conjunction with water chemistry analyses and cell counts. Universal primers for the SSU rRNA gene sequences for Eukarya, Bacteria, and Archaea were used for barcoded pyrosequence determination. The environmental parameters that most closely correlated with C. vulgaris abundance were pH and phosphate. Community analyses indicated that the pond system remained dominated by the Chlorella population (93% of eukaryotic sequences), but was also colonized by other microorganisms. Bacterial sequence diversity increased over time while archaeal sequence diversity declined over the same time period. Using SparCC co-occurrence network analysis, a positive correlation was observed between C. vulgaris and Pseudomonas sp. throughout the experiment, which may suggest a symbiotic relationship between the two organisms. The putative relationship coupled with high pH may have contributed to the success of C. vulgaris. The characterization of the microbial community dynamics of an alkaliphilic open pond system provides significant insight into open pond systems that could be used to control photoautotrophic biomass productivity in an open, non-sterile environment.
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Affiliation(s)
- Tisza A. S. Bell
- Department of Microbiology and Immunology, Montana State University, BozemanMT, USA
- Energy Research Institute, Montana State University, BozemanMT, USA
| | - Bharath Prithiviraj
- Department of Civil, Environmental and Architectural Engineering, University of Colorado, BoulderCO, USA
- Plant Biology Division, The Samuel Roberts Noble Foundation, ArdmoreOK, USA
| | - Brad D. Wahlen
- Department of Chemistry and Biochemistry, Utah State University, LoganUT, USA
| | - Matthew W. Fields
- Department of Microbiology and Immunology, Montana State University, BozemanMT, USA
- Energy Research Institute, Montana State University, BozemanMT, USA
- Center for Biofilm Engineering, Montana State University, BozemanMT, USA
| | - Brent M. Peyton
- Energy Research Institute, Montana State University, BozemanMT, USA
- Center for Biofilm Engineering, Montana State University, BozemanMT, USA
- Department of Chemical and Biological Engineering, Montana State University, BozemanMT, USA
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Affiliation(s)
- Eric S Boyd
- Department of Microbiology and Immunology, Thermal Biology Institute, Montana State University, Bozeman, MT, 59717, USA
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Brileya KA, Camilleri LB, Zane GM, Wall JD, Fields MW. Biofilm growth mode promotes maximum carrying capacity and community stability during product inhibition syntrophy. Front Microbiol 2014; 5:693. [PMID: 25566209 PMCID: PMC4266047 DOI: 10.3389/fmicb.2014.00693] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 11/22/2014] [Indexed: 12/03/2022] Open
Abstract
Sulfate-reducing bacteria (SRB) can interact syntrophically with other community members in the absence of sulfate, and interactions with hydrogen-consuming methanogens are beneficial when these archaea consume potentially inhibitory H2 produced by the SRB. A dual continuous culture approach was used to characterize population structure within a syntrophic biofilm formed by the SRB Desulfovibrio vulgaris Hildenborough and the methanogenic archaeum Methanococcus maripaludis. Under the tested conditions, monocultures of D. vulgaris formed thin, stable biofilms, but monoculture M. maripaludis did not. Microscopy of intact syntrophic biofilm confirmed that D. vulgaris formed a scaffold for the biofilm, while intermediate and steady-state images revealed that M. maripaludis joined the biofilm later, likely in response to H2 produced by the SRB. Close interactions in structured biofilm allowed efficient transfer of H2 to M. maripaludis, and H2 was only detected in cocultures with a mutant SRB that was deficient in biofilm formation (ΔpilA). M. maripaludis produced more carbohydrate (uronic acid, hexose, and pentose) as a monoculture compared to total coculture biofilm, and this suggested an altered carbon flux during syntrophy. The syntrophic biofilm was structured into ridges (∼300 × 50 μm) and models predicted lactate limitation at ∼50 μm biofilm depth. The biofilm had structure that likely facilitated mass transfer of H2 and lactate, yet maximized biomass with a more even population composition (number of each organism) when compared to the bulk-phase community. Total biomass protein was equivalent in lactate-limited and lactate-excess conditions when a biofilm was present, but in the absence of biofilm, total biomass protein was significantly reduced. The results suggest that multispecies biofilms create an environment conducive to resource sharing, resulting in increased biomass retention, or carrying capacity, for cooperative populations.
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Affiliation(s)
- Kristen A Brileya
- Department of Microbiology and Immunology, Montana State University Bozeman, MT, USA ; Center for Biofilm Engineering, Montana State University Bozeman, MT, USA
| | - Laura B Camilleri
- Department of Microbiology and Immunology, Montana State University Bozeman, MT, USA ; Center for Biofilm Engineering, Montana State University Bozeman, MT, USA
| | - Grant M Zane
- Division of Biochemistry, University of Missouri Columbia, MO, USA
| | - Judy D Wall
- Division of Biochemistry, University of Missouri Columbia, MO, USA
| | - Matthew W Fields
- Department of Microbiology and Immunology, Montana State University Bozeman, MT, USA ; Center for Biofilm Engineering, Montana State University Bozeman, MT, USA ; Thermal Biology Institute, Montana State University Bozeman, MT, USA ; Ecosystems and Networks Integrated with Genes and Molecular Assemblies Berkeley, CA, USA ; National Center for Genome Resources Santa Fe, NM, USA
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