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Sudo M, Osvatic J, Taylor JD, Dufour SC, Prathep A, Wilkins LGE, Rattei T, Yuen B, Petersen JM. SoxY gene family expansion underpins adaptation to diverse hosts and environments in symbiotic sulfide oxidizers. mSystems 2024; 9:e0113523. [PMID: 38747602 PMCID: PMC11237559 DOI: 10.1128/msystems.01135-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 04/13/2024] [Indexed: 06/19/2024] Open
Abstract
Sulfur-oxidizing bacteria (SOB) have developed distinct ecological strategies to obtain reduced sulfur compounds for growth. These range from specialists that can only use a limited range of reduced sulfur compounds to generalists that can use many different forms as electron donors. Forming intimate symbioses with animal hosts is another highly successful ecological strategy for SOB, as animals, through their behavior and physiology, can enable access to sulfur compounds. Symbioses have evolved multiple times in a range of animal hosts and from several lineages of SOB. They have successfully colonized a wide range of habitats, from seagrass beds to hydrothermal vents, with varying availability of symbiont energy sources. Our extensive analyses of sulfur transformation pathways in 234 genomes of symbiotic and free-living SOB revealed widespread conservation in metabolic pathways for sulfur oxidation in symbionts from different host species and environments, raising the question of how they have adapted to such a wide range of distinct habitats. We discovered a gene family expansion of soxY in these genomes, with up to five distinct copies per genome. Symbionts harboring only the "canonical" soxY were typically ecological "specialists" that are associated with specific host subfamilies or environments (e.g., hydrothermal vents, mangroves). Conversely, symbionts with multiple divergent soxY genes formed versatile associations across diverse hosts in various marine environments. We hypothesize that expansion and diversification of the soxY gene family could be one genomic mechanism supporting the metabolic flexibility of symbiotic SOB enabling them and their hosts to thrive in a range of different and dynamic environments.IMPORTANCESulfur metabolism is thought to be one of the most ancient mechanisms for energy generation in microorganisms. A diverse range of microorganisms today rely on sulfur oxidation for their metabolism. They can be free-living, or they can live in symbiosis with animal hosts, where they power entire ecosystems in the absence of light, such as in the deep sea. In the millions of years since they evolved, sulfur-oxidizing bacteria have adopted several highly successful strategies; some are ecological "specialists," and some are "generalists," but which genetic features underpin these ecological strategies are not well understood. We discovered a gene family that has become expanded in those species that also seem to be "generalists," revealing that duplication, repurposing, and reshuffling existing genes can be a powerful mechanism driving ecological lifestyle shifts.
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Affiliation(s)
- Marta Sudo
- University of Vienna, Centre for Microbiology and Environmental Systems Science, Vienna, Austria
- Doctoral School in Microbiology and Environmental Science, University of Vienna, Vienna, Austria
| | - Jay Osvatic
- Joint Microbiome Facility of the Medical University of Vienna and the University of Vienna, Vienna, Austria
- Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria
| | - John D. Taylor
- Life Sciences, The Natural History Museum, London, United Kingdom
| | - Suzanne C. Dufour
- Department of Biology, Memorial University of Newfoundland, St. John’s, Newfoundland, Canada
| | - Anchana Prathep
- Department of Biology, Faculty of Science, Prince of Songkla University, HatYai, Thailand
| | - Laetitia G. E. Wilkins
- Eco-Evolutionary Interactions Group, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Thomas Rattei
- University of Vienna, Centre for Microbiology and Environmental Systems Science, Vienna, Austria
| | - Benedict Yuen
- University of Vienna, Centre for Microbiology and Environmental Systems Science, Vienna, Austria
- Eco-Evolutionary Interactions Group, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Jillian M. Petersen
- University of Vienna, Centre for Microbiology and Environmental Systems Science, Vienna, Austria
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2
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Zhang R, Liu P, Wang Y, Roberts AP, Bai J, Liu Y, Zhu K, Du Z, Chen G, Pan Y, Li J. Phylogenetics and biomineralization of a novel magnetotactic Gammaproteobacterium from a freshwater lake in Beijing, China. FEMS Microbiol Ecol 2023; 99:fiad150. [PMID: 37974050 DOI: 10.1093/femsec/fiad150] [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: 07/04/2023] [Revised: 11/09/2023] [Accepted: 11/15/2023] [Indexed: 11/19/2023] Open
Abstract
Magnetotactic bacteria (MTB) have the remarkable capability of producing intracellularly membrane-enveloped magnetic nanocrystals (i.e. magnetosomes) and swimming along geomagnetic field lines. Despite more than 50 years of research, bacterial diversity and magnetosome biomineralization within MTB are relatively less known in the Gammaproteobacteria class than other groups. This is incompatible with the status of Gammaproteobacteria as the most diverse class of gram-negative bacteria with a number of ecologically important bacteria. Here, we identify a novel MTB strain YYHR-1 affiliated with the Gammaproteobacteria class of the Pseudomonadota phylum from a freshwater lake. In YYHR-1, most magnetosome crystals are organized into a long chain aligned along the cell long axis; unusually, a few small superparamagnetic crystals are located at the side of the chain, off the main chain axis. Micromagnetic simulations indicate that magnetostatic interactions among adjacent crystals within a chain reduce the Gibbs energy to enhance chain stability. Genomic analysis suggests that duplication of magnetosome gene clusters may result in off-chain magnetosomes formation. By integrating available genomic data from Gammaproteobacteria, the phylogenetic position of MTB in this class is reassigned here. Our new findings expand knowledge about MTB diversity and magnetosome biomineralization, and deepen understanding of the phylogenetics of the Gammaproteobacteria.
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Affiliation(s)
- Rongrong Zhang
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing 100029, China
- Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China
- Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519082, China
- Marine College, Shandong University, Weihai 264209, China
| | - Peiyu Liu
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing 100029, China
- Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China
- Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519082, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuqin Wang
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing 100029, China
- Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China
- Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519082, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Andrew P Roberts
- Research School of Earth Sciences, Australian National University, Canberra, ACT 2601, Australia
| | - Jinling Bai
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing 100029, China
- Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China
- Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519082, China
- Marine College, Shandong University, Weihai 264209, China
| | - Yan Liu
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing 100029, China
- Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China
- Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519082, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kelei Zhu
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing 100029, China
- Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China
- Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519082, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zongjun Du
- Marine College, Shandong University, Weihai 264209, China
| | - Guanjun Chen
- Marine College, Shandong University, Weihai 264209, China
| | - Yongxin Pan
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing 100029, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jinhua Li
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing 100029, China
- Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
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3
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Perner M, Wallmann K, Adam-Beyer N, Hepach H, Laufer-Meiser K, Böhnke S, Diercks I, Bange HW, Indenbirken D, Nikeleit V, Bryce C, Kappler A, Engel A, Scholz F. Environmental changes affect the microbial release of hydrogen sulfide and methane from sediments at Boknis Eck (SW Baltic Sea). Front Microbiol 2022; 13:1096062. [PMID: 36620042 PMCID: PMC9822571 DOI: 10.3389/fmicb.2022.1096062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022] Open
Abstract
Anthropogenic activities are modifying the oceanic environment rapidly and are causing ocean warming and deoxygenation, affecting biodiversity, productivity, and biogeochemical cycling. In coastal sediments, anaerobic organic matter degradation essentially fuels the production of hydrogen sulfide and methane. The release of these compounds from sediments is detrimental for the (local) environment and entails socio-economic consequences. Therefore, it is vital to understand which microbes catalyze the re-oxidation of these compounds under environmental dynamics, thereby mitigating their release to the water column. Here we use the seasonally dynamic Boknis Eck study site (SW Baltic Sea), where bottom waters annually fall hypoxic or anoxic after the summer months, to extrapolate how the microbial community and its activity reflects rising temperatures and deoxygenation. During October 2018, hallmarked by warmer bottom water and following a hypoxic event, modeled sulfide and methane production and consumption rates are higher than in March at lower temperatures and under fully oxic bottom water conditions. The microbial populations catalyzing sulfide and methane metabolisms are found in shallower sediment zones in October 2018 than in March 2019. DNA-and RNA profiling of sediments indicate a shift from primarily organotrophic to (autotrophic) sulfide oxidizing Bacteria, respectively. Previous studies using data collected over decades demonstrate rising temperatures, decreasing eutrophication, lower primary production and thus less fresh organic matter transported to the Boknis Eck sediments. Elevated temperatures are known to stimulate methanogenesis, anaerobic oxidation of methane, sulfate reduction and essentially microbial sulfide consumption, likely explaining the shift to a phylogenetically more diverse sulfide oxidizing community based on RNA.
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Affiliation(s)
- Mirjam Perner
- Department of Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Klaus Wallmann
- Department of Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Nicole Adam-Beyer
- Department of Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Helmke Hepach
- Department of Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Katja Laufer-Meiser
- Department of Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Stefanie Böhnke
- Department of Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Isabel Diercks
- Department of Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Hermann W. Bange
- Department of Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | | | - Verena Nikeleit
- Department of Geomicrobiology and Geosciences, University of Tübingen, Tübingen, Germany
| | - Casey Bryce
- Department of Geomicrobiology and Geosciences, University of Tübingen, Tübingen, Germany
- School of Earth Sciences, University of Bristol, Bristol, United Kingdom
| | - Andreas Kappler
- Department of Geomicrobiology and Geosciences, University of Tübingen, Tübingen, Germany
| | - Anja Engel
- Department of Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Florian Scholz
- Department of Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
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4
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Gomes ML, Klatt JM, Dick GJ, Grim SL, Rico KI, Medina M, Ziebis W, Kinsman-Costello L, Sheldon ND, Fike DA. Sedimentary pyrite sulfur isotope compositions preserve signatures of the surface microbial mat environment in sediments underlying low-oxygen cyanobacterial mats. GEOBIOLOGY 2022; 20:60-78. [PMID: 34331395 DOI: 10.1111/gbi.12466] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 07/10/2021] [Indexed: 06/13/2023]
Abstract
The sedimentary pyrite sulfur isotope (δ34 S) record is an archive of ancient microbial sulfur cycling and environmental conditions. Interpretations of pyrite δ34 S signatures in sediments deposited in microbial mat ecosystems are based on studies of modern microbial mat porewater sulfide δ34 S geochemistry. Pyrite δ34 S values often capture δ34 S signatures of porewater sulfide at the location of pyrite formation. However, microbial mats are dynamic environments in which biogeochemical cycling shifts vertically on diurnal cycles. Therefore, there is a need to study how the location of pyrite formation impacts pyrite δ34 S patterns in these dynamic systems. Here, we present diurnal porewater sulfide δ34 S trends and δ34 S values of pyrite and iron monosulfides from Middle Island Sinkhole, Lake Huron. The sediment-water interface of this sinkhole hosts a low-oxygen cyanobacterial mat ecosystem, which serves as a useful location to explore preservation of sedimentary pyrite δ34 S signatures in early Earth environments. Porewater sulfide δ34 S values vary by up to ~25‰ throughout the day due to light-driven changes in surface microbial community activity that propagate downwards, affecting porewater geochemistry as deep as 7.5 cm in the sediment. Progressive consumption of the sulfate reservoir drives δ34 S variability, instead of variations in average cell-specific sulfate reduction rates and/or sulfide oxidation at different depths in the sediment. The δ34 S values of pyrite are similar to porewater sulfide δ34 S values near the mat surface. We suggest that oxidative sulfur cycling and other microbial activity promote pyrite formation in and immediately adjacent to the microbial mat and that iron geochemistry limits further pyrite formation with depth in the sediment. These results imply that primary δ34 S signatures of pyrite deposited in organic-rich, iron-poor microbial mat environments capture information about microbial sulfur cycling and environmental conditions at the mat surface and are only minimally affected by deeper sedimentary processes during early diagenesis.
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Affiliation(s)
- Maya L Gomes
- Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Judith M Klatt
- Microsensor Group, Max Planck Institute for Marine Microbiology, Bremen, Germany
- Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI, USA
| | - Gregory J Dick
- Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI, USA
| | - Sharon L Grim
- Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI, USA
- Exobiology Branch, National Aeronautics and Space Administration Ames Research Center, Mountain View, CA, USA
| | - Kathryn I Rico
- Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI, USA
- Department of Earth and Planetary Sciences, McGill University, Montreal, QC, Canada
| | - Matthew Medina
- Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI, USA
| | - Wiebke Ziebis
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | | | - Nathan D Sheldon
- Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI, USA
| | - David A Fike
- Department of Earth and Planetary Sciences, Washington University, Saint Louis, MO, USA
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5
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Jørgensen BB. Unravelling the sulphur cycle of marine sediments. Environ Microbiol 2019; 21:3533-3538. [DOI: 10.1111/1462-2920.14721] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 06/18/2019] [Indexed: 11/28/2022]
Affiliation(s)
- Bo Barker Jørgensen
- Center for Geomicrobiology, Department of BioscienceAarhus University Denmark
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6
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Jørgensen BB, Findlay AJ, Pellerin A. The Biogeochemical Sulfur Cycle of Marine Sediments. Front Microbiol 2019. [DOI: 10.10.3389/fmicb.2019.00849] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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7
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Jørgensen BB, Findlay AJ, Pellerin A. The Biogeochemical Sulfur Cycle of Marine Sediments. Front Microbiol 2019; 10:849. [PMID: 31105660 PMCID: PMC6492693 DOI: 10.3389/fmicb.2019.00849] [Citation(s) in RCA: 210] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 04/02/2019] [Indexed: 11/13/2022] Open
Abstract
Microbial dissimilatory sulfate reduction to sulfide is a predominant terminal pathway of organic matter mineralization in the anoxic seabed. Chemical or microbial oxidation of the produced sulfide establishes a complex network of pathways in the sulfur cycle, leading to intermediate sulfur species and partly back to sulfate. The intermediates include elemental sulfur, polysulfides, thiosulfate, and sulfite, which are all substrates for further microbial oxidation, reduction or disproportionation. New microbiological discoveries, such as long-distance electron transfer through sulfide oxidizing cable bacteria, add to the complexity. Isotope exchange reactions play an important role for the stable isotope geochemistry and for the experimental study of sulfur transformations using radiotracers. Microbially catalyzed processes are partly reversible whereby the back-reaction affects our interpretation of radiotracer experiments and provides a mechanism for isotope fractionation. We here review the progress and current status in our understanding of the sulfur cycle in the seabed with respect to its microbial ecology, biogeochemistry, and isotope geochemistry.
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Affiliation(s)
- Bo Barker Jørgensen
- Department of Bioscience, Center for Geomicrobiology, Aarhus University, Aarhus, Denmark
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8
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Kamp A, Petro C, Røy H, Nielsen S, Carvalho P, Stief P, Schramm A. Intracellular nitrate in sediments of an oxygen-deficient marine basin is linked to pelagic diatoms. FEMS Microbiol Ecol 2018; 94:5040219. [PMID: 29931199 DOI: 10.1093/femsec/fiy122] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 06/15/2018] [Indexed: 11/13/2022] Open
Abstract
Intracellular nitrate is an important electron acceptor in oxygen-deficient aquatic environments, either for the nitrate-storing microbes themselves, or for ambient microbial communities through nitrate leakage. This study links the spatial distribution of intracellular nitrate with the abundance and identity of nitrate-storing microbes in sediments of the Bornholm Basin, an environmental showcase for severe hypoxia. Intracellular nitrate (up to 270 nmol cm-3 sediment) was detected at all 18 stations along a 35-km transect through the basin and typically extended as deep as 1.6 cm into the sediment. Intracellular nitrate contents were particularly high at stations where chlorophyll contents suggested high settling rates of pelagic primary production. The depth distribution of intracellular nitrate matched that of the diatom-specific photopigment fucoxanthin in the upper 1.6 cm and calculations support that diatoms are the major nitrate-storing microbes in these sediments. In contrast, other known nitrate-storing microbes, such as sulfide-oxidizing bacteria and foraminifers, played only a minor role, if any. Strikingly, 18S rRNA gene sequencing revealed that the majority of the diatoms in the sediment were pelagic species. We conclude that intracellular nitrate stored by pelagic diatoms is transported to the seafloor by settling phytoplankton blooms, implying a so far overlooked 'biological nitrate pump'.
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Affiliation(s)
- Anja Kamp
- AIAS, Aarhus Institute of Advanced Studies, Aarhus University, Aarhus, Denmark.,Center for Geomicrobiology and Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Caitlin Petro
- Center for Geomicrobiology and Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Hans Røy
- Center for Geomicrobiology and Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Susanne Nielsen
- Center for Geomicrobiology and Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Pedro Carvalho
- Department of Environmental Science, Aarhus University, Roskilde, Denmark
| | - Peter Stief
- Nordcee, Department of Biology, University of Southern Denmark, Odense, Denmark
| | - Andreas Schramm
- Center for Geomicrobiology and Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
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Martin BC, Gleeson D, Statton J, Siebers AR, Grierson P, Ryan MH, Kendrick GA. Low Light Availability Alters Root Exudation and Reduces Putative Beneficial Microorganisms in Seagrass Roots. Front Microbiol 2018; 8:2667. [PMID: 29375529 PMCID: PMC5768916 DOI: 10.3389/fmicb.2017.02667] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 12/21/2017] [Indexed: 01/05/2023] Open
Abstract
Seagrass roots host a diverse microbiome that is critical for plant growth and health. Composition of microbial communities can be regulated in part by root exudates, but the specifics of these interactions in seagrass rhizospheres are still largely unknown. As light availability controls primary productivity, reduced light may impact root exudation and consequently the composition of the root microbiome. Hence, we analyzed the influence of light availability on root exudation and community structure of the root microbiome of three co-occurring seagrass species, Halophila ovalis, Halodule uninervis and Cymodocea serrulata. Plants were grown under four light treatments in mesocosms for 2 weeks; control (100% surface irradiance (SI), medium (40% SI), low (20% SI) and fluctuating light (10 days 20% and 4 days 100%). 16S rDNA amplicon sequencing revealed that microbial diversity, composition and predicted function were strongly influenced by the presence of seagrass roots, such that root microbiomes were unique to each seagrass species. Reduced light availability altered seagrass root exudation, as characterized using fluorescence spectroscopy, and altered the composition of seagrass root microbiomes with a reduction in abundance of potentially beneficial microorganisms. Overall, this study highlights the potential for above-ground light reduction to invoke a cascade of changes from alterations in root exudation to a reduction in putative beneficial microorganisms and, ultimately, confirms the importance of the seagrass root environment - a critical, but often overlooked space.
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Affiliation(s)
- Belinda C. Martin
- School of Biological Sciences, The University of Western Australia, Crawley, WA, Australia
- UWA Oceans Institute, The University of Western Australia, Crawley, WA, Australia
| | - Deirdre Gleeson
- School of Agriculture and Environment, The University of Western Australia, Crawley, WA, Australia
| | - John Statton
- School of Biological Sciences, The University of Western Australia, Crawley, WA, Australia
- UWA Oceans Institute, The University of Western Australia, Crawley, WA, Australia
- Western Australian Marine Science Institution, Perth, WA, Australia
| | - Andre R. Siebers
- School of Biological Sciences, The University of Western Australia, Crawley, WA, Australia
| | - Pauline Grierson
- School of Biological Sciences, The University of Western Australia, Crawley, WA, Australia
- West Australian Biogeochemistry Centre, School of Biological Sciences, The University of Western Australia, Crawley, WA, Australia
| | - Megan H. Ryan
- School of Agriculture and Environment, The University of Western Australia, Crawley, WA, Australia
| | - Gary A. Kendrick
- School of Biological Sciences, The University of Western Australia, Crawley, WA, Australia
- UWA Oceans Institute, The University of Western Australia, Crawley, WA, Australia
- Western Australian Marine Science Institution, Perth, WA, Australia
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10
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Bjerg JT, Damgaard LR, Holm SA, Schramm A, Nielsen LP. Motility of Electric Cable Bacteria. Appl Environ Microbiol 2016; 82:3816-21. [PMID: 27084019 PMCID: PMC4907201 DOI: 10.1128/aem.01038-16] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 04/13/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Cable bacteria are filamentous bacteria that electrically couple sulfide oxidation and oxygen reduction at centimeter distances, and observations in sediment environments have suggested that they are motile. By time-lapse microscopy, we found that cable bacteria used gliding motility on surfaces with a highly variable speed of 0.5 ± 0.3 μm s(-1) (mean ± standard deviation) and time between reversals of 155 ± 108 s. They frequently moved forward in loops, and formation of twisted loops revealed helical rotation of the filaments. Cable bacteria responded to chemical gradients in their environment, and around the oxic-anoxic interface, they curled and piled up, with straight parts connecting back to the source of sulfide. Thus, it appears that motility serves the cable bacteria in establishing and keeping optimal connections between their distant electron donor and acceptors in a dynamic sediment environment. IMPORTANCE This study reports on the motility of cable bacteria, capable of transmitting electrons over centimeter distances. It gives us a new insight into their behavior in sediments and explains previously puzzling findings. Cable bacteria greatly influence their environment, and this article adds significantly to the body of knowledge about this organism.
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Affiliation(s)
- Jesper Tataru Bjerg
- Center for Geomicrobiology, Department of Bioscience, Aarhus University, Aarhus, Denmark Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Lars Riis Damgaard
- Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Simon Agner Holm
- Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Andreas Schramm
- Center for Geomicrobiology, Department of Bioscience, Aarhus University, Aarhus, Denmark Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Lars Peter Nielsen
- Center for Geomicrobiology, Department of Bioscience, Aarhus University, Aarhus, Denmark Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
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11
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El-Hajj ZW, Newman EB. How much territory can a single E. coli cell control? Front Microbiol 2015; 6:309. [PMID: 25954251 PMCID: PMC4404868 DOI: 10.3389/fmicb.2015.00309] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 03/29/2015] [Indexed: 11/20/2022] Open
Abstract
Bacteria have been traditionally classified in terms of size and shape and are best known for their very small size. Escherichia coli cells in particular are small rods, each 1–2 μ. However, the size varies with the medium, and faster growing cells are larger because they must have more ribosomes to make more protoplasm per unit time, and ribosomes take up space. Indeed, Maaløe’s experiments on how E. coli establishes its size began with shifts between rich and poor media. Recently much larger bacteria have been described, including Epulopiscium fishelsoni at 700 μm and Thiomargarita namibiensis at 750 μm. These are not only much longer than E. coli cells but also much wider, necessitating considerable intracellular organization. Epulopiscium cells for instance, at 80 μm wide, enclose a large enough volume of cytoplasm to present it with major transport problems. This review surveys E. coli cells much longer than those which grow in nature and in usual lab cultures. These include cells mutated in a single gene (metK) which are 2–4 × longer than their non-mutated parent. This metK mutant stops dividing when slowly starved of S-adenosylmethionine but continues to elongate to 50 μm and more. FtsZ mutants have been routinely isolated as long cells which form during growth at 42°C. The SOS response is a well-characterized regulatory network that is activated in response to DNA damage and also results in cell elongation. Our champion elongated E. coli is a metK strain with a further, as yet unidentified mutation, which reaches 750 μm with no internal divisions and no increase in width.
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Affiliation(s)
- Ziad W El-Hajj
- Department of Biology, Concordia University , Montreal, QC, Canada
| | - Elaine B Newman
- Department of Biology, Concordia University , Montreal, QC, Canada
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12
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Flood BE, Bailey JV, Biddle JF. Horizontal gene transfer and the rock record: comparative genomics of phylogenetically distant bacteria that induce wrinkle structure formation in modern sediments. GEOBIOLOGY 2014; 12:119-132. [PMID: 24382125 DOI: 10.1111/gbi.12072] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2013] [Accepted: 11/27/2013] [Indexed: 06/03/2023]
Abstract
Wrinkle structures are sedimentary features that are produced primarily through the trapping and binding of siliciclastic sediments by mat-forming micro-organisms. Wrinkle structures and related sedimentary structures in the rock record are commonly interpreted to represent the stabilizing influence of cyanobacteria on sediments because cyanobacteria are known to produce similar textures and structures in modern tidal flat settings. However, other extant bacteria such as filamentous representatives of the family Beggiatoaceae can also interact with sediments to produce sedimentary features that morphologically resemble many of those associated with cyanobacteria-dominated mats. While Beggiatoa spp. and cyanobacteria are metabolically and phylogenetically distant, genomic analyses show that the two groups share hundreds of homologous genes, likely as the result of horizontal gene transfer. The comparative genomics results described here suggest that some horizontally transferred genes may code for phenotypic traits such as filament formation, chemotaxis, and the production of extracellular polymeric substances that potentially underlie the similar biostabilizing influences of these organisms on sediments. We suggest that the ecological utility of certain basic life modes such as the construction of mats and biofilms, coupled with the lateral mobility of genes in the microbial world, introduces an element of uncertainty into the inference of specific phylogenetic origins from gross morphological features preserved in the ancient rock record.
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Affiliation(s)
- B E Flood
- Department of Earth Sciences, University of Minnesota- Twin Cities, Minneapolis, MN, USA
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13
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MacGregor BJ, Biddle JF, Harbort C, Matthysse AG, Teske A. Sulfide oxidation, nitrate respiration, carbon acquisition, and electron transport pathways suggested by the draft genome of a single orange Guaymas Basin Beggiatoa (Cand. Maribeggiatoa) sp. filament. Mar Genomics 2013; 11:53-65. [PMID: 24012537 DOI: 10.1016/j.margen.2013.08.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 08/12/2013] [Accepted: 08/12/2013] [Indexed: 12/27/2022]
Abstract
A near-complete draft genome has been obtained for a single vacuolated orange Beggiatoa (Cand. Maribeggiatoa) filament from a Guaymas Basin seafloor microbial mat, the third relatively complete sequence for the Beggiatoaceae. Possible pathways for sulfide oxidation; nitrate respiration; inorganic carbon fixation by both Type II RuBisCO and the reductive tricarboxylic acid cycle; acetate and possibly formate uptake; and energy-generating electron transport via both oxidative phosphorylation and the Rnf complex are discussed here. A role in nitrite reduction is suggested for an abundant orange cytochrome produced by the Guaymas strain; this has a possible homolog in Beggiatoa (Cand. Isobeggiatoa) sp. PS, isolated from marine harbor sediment, but not Beggiatoa alba B18LD, isolated from a freshwater rice field ditch. Inferred phylogenies for the Calvin-Benson-Bassham (CBB) cycle and the reductive (rTCA) and oxidative (TCA) tricarboxylic acid cycles suggest that genes encoding succinate dehydrogenase and enzymes for carboxylation and/or decarboxylation steps (including RuBisCO) may have been introduced to (or exported from) one or more of the three genomes by horizontal transfer, sometimes by different routes. Sequences from the two marine strains are generally more similar to each other than to sequences from the freshwater strain, except in the case of RuBisCO: only the Guaymas strain encodes a Type II enzyme, which (where studied) discriminates less against oxygen than do Type I RuBisCOs. Genes subject to horizontal transfer may represent key steps for adaptation to factors such as oxygen and carbon dioxide concentration, organic carbon availability, and environmental variability.
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Affiliation(s)
- Barbara J MacGregor
- Department of Marine Sciences, University of North Carolina - Chapel Hill, Chapel Hill, NC 27599, USA.
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