The Effect of Bacterial Sulfate Reduction Inhibition on the Production and Stable Isotopic Composition of Methane in Hypersaline Environments

Kelley, Cheryl A.; Bebout, Brad M.; Chanton, Jeffrey P.; Detweiler, Angela M.; Frisbee, Adrienne; Nicholson, B. E.; Poole, Jennifer; Tazaz, Amanda M.; Winkler, Claire

doi:10.1007/s10498-019-09362-x

Cited by 4 publications

(3 citation statements)

References 28 publications

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“…While originally thought to be thermodynamically unfavorable at high salinities ( 54 ), some studies have reported low, yet present, sulfate reduction rates in hypersaline sediments and mats ( 11 , 55 – 57 ). Other recent reports, however, still come to the conclusion that sulfate reduction is inhibited at salt saturation ( 58 , 59 ). Our data suggest that at extreme salinities, even if growth of sulfate reducers is stopped, energy generation might still continue, albeit at a lower rate.…”

Section: Discussionmentioning

confidence: 96%

Limitation of Microbial Processes at Saturation-Level Salinities in a Microbial Mat Covering a Coastal Salt Flat

Meier

Greve

Chennu

et al. 2021

Appl Environ Microbiol

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Hypersaline microbial mats are dense microbial ecosystems capable of performing complete element cycling and are considered analogs of Early Earth and hypothetical extraterrestrial ecosystems. We studied the functionality and limits of key biogeochemical processes, such as photosynthesis, aerobic respiration, and sulfur cycling in salt crust-covered microbial mats from a tidal flat at the coast of Oman. We measured light, oxygen, and sulfide microprofiles as well as sulfate-reduction rates at salt saturation and in flood conditions and determined fine-scale stratification of pigments, biomass, and microbial taxa in the resident microbial community. The salt crust did not protect the mats against irradiation or evaporation. Although some oxygen production was measurable at salinity ≤ 30% (w/v) in situ , at saturation-level salinity (40%), oxygenic photosynthesis was completely inhibited and only resumed two days after reducing the pore water salinity to 12%. Aerobic respiration and active sulfur cycling occurred at low rates under salt saturation and increased strongly upon salinity reduction. Apart from high relative abundances of Chloroflexi, photoheterotrophic Alphaproteobacteria , Bacteroidetes , and Archaea, the mat contained a distinct layer harboring filamentous Cyanobacteria , which is unusual for such high salinities. Our results show that the diverse microbial community inhabiting this saltflat mat ultimately depends on periodic salt dilution to be self-sustaining and is rather adapted to merely survive salt saturation than to thrive under the salt crust. Importance Due to their abilities to survive intense radiation and low water availability hypersaline microbial mats are often suggested to be analogs of potential extraterrestrial life. However, even on Earth the limitations imposed on microbial processes by saturation-level salinity have rarely been studied in situ . While abundance and diversity of microbial life in salt-saturated environments is well documented, most of our knowledge on process limitations stems from culture-based studies, few in situ studies, and theoretical calculations. Especially oxygenic photosynthesis has barely been explored beyond 5M NaCl (28% w/v). By applying a variety of biogeochemical and molecular methods we show that despite abundance of photoautotrophic microorganisms, oxygenic photosynthesis is inhibited in salt-crust covered microbial mats at saturation salinities, while rates of other energy generation processes are decreased several fold. Hence, the complete element cycling required for self-sustaining microbial communities only occurs at lower salt concentrations.

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Section: Discussionmentioning

confidence: 96%

Limitation of Microbial Processes at Saturation-Level Salinities in a Microbial Mat Covering a Coastal Salt Flat

Meier

Greve

Chennu

et al. 2021

Appl Environ Microbiol

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“…Based on GHG and microbiological characterization, these ecosystems have been classified as sensitive areas for global warming due to the impact on CH 4 emissions mediated by H 2 /CO 2 -based methanogens stimulation [ 22 ], highlighting the role of temperature as a driving factor of CH 4 emissions globally [ 23 ]. Additional studies have provided insights for desert coastal wetlands in Atacama mainly associated with drainage catchment areas and river mouths [ 24 , 25 ] and hypersaline pools [ 26 ], where salinity and substrate availability control methanogenesis/sulfate reduction competition. To our knowledge, there are no studies exploring the relation between GHG distribution and microbial communities in coastal wetlands of the semiarid region of central-northern area, as a transition between the hyper arid and humid areas.…”

Section: Introductionmentioning

confidence: 99%

Dissolved greenhouse gases and benthic microbial communities in coastal wetlands of the Chilean coast semiarid region

et al. 2022

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Coastal wetlands are ecosystems associated with intense carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) recycling, modulated by salinity and other environmental factors that influence the microbial community involved in greenhouse gases production and consumption. In this study, we evaluated the influence of environmental factors on GHG concentration and benthic microbial community composition in coastal wetlands along the coast of the semiarid region. Wetlands were situated in landscapes along a south-north gradient of higher aridity and lower anthropogenic impact. Our results indicate that wetlands have a latitudinal variability associated with higher organic matter content at the north, especially in summer, and higher nutrient concentration at the south, predominantly in winter. During our sampling, wetlands were characterized by positive CO2 μM and CH4 nM excess, and a shift of N2O nM excess from negative to positive values from the north to the south. Benthic microbial communities were taxonomically diverse with > 60 phyla, especially in low frequency taxa. Highly abundant bacterial phyla were classified into Gammaproteobacteria (Betaproteobacteria order), Alphaproteobacteria and Deltaproteobacteria, including key functional groups such as nitrifying and methanotrophic bacteria. Generalized additive model (GAM) indicated that conductivity accounted for the larger variability of CH4 and CO2, but the predictions of CH4 and CO2 concentration were improved when latitude and pH concentration were included. Nitrate and latitude were the best predictors to account for the changes in the dissolved N2O distribution. Structural equation modeling (SEM), illustrated how the environment significantly influences functional microbial groups (nitrifiers and methane oxidizers) and their resulting effect on GHG distribution. Our results highlight the combined role of salinity and substrates of key functional microbial groups with metabolisms associated with both carbon and nitrogen, influencing dissolved GHG and their potential exchange in natural and anthropogenically impacted coastal wetlands.

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“…In addition to the good science contained in these papers, their acknowledgments also contain moving testaments about how Mark touched all of our lives in so many different ways. Lastly, please note that two of the papers submitted to this special issue (Kelley et al 2019;Klun et al 2019) were inadvertently published in a regular issue of Aquatic Geochemistry in late 2019 Fig. 1 Professor Mark Hines (1950Hines ( -2018 (vol.…”

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confidence: 99%

An Introduction to “Microbial Biogeochemistry: A Special Issue of Aquatic Geochemistry Honoring Mark Hines”

Lyons

Burdige

2020

Aquat Geochem

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This issue of Aquatic Geochemistry is dedicated to the memory of Dr. Mark E. Hines (Fig. 1) and his contributions to the fields of microbial biogeochemistry and aquatic geochemistry. Mark passed away in March of 2018, and through his career as a researcher, teacher, mentor, colleague, and university administrator, he greatly influenced the lives of all around him. We hope that this volume will serve not only as a memory of Mark, but also as a way to recognize his significant influences and major contributions in the fields of carbon, sulfur, and trace element biogeochemistry.Mark received his BS from the Ohio State University in 1973, his MS from the University of Connecticut in 1978, and his Ph.D. from the University of New Hampshire in 1981, with all degrees in Microbiology. After the awarding of his Ph.D., Mark stayed on at the University of New Hampshire from 1981 to 1995 as a research staff member and then a research faculty member. He moved to the University of Alaska, Anchorage in 1995, and was a faculty member there until 2002. From that time onward until his death, he was a member of the Dept. of Biological Sciences at University of Massachusetts, Lowell, being promoted to Full Professor in 2005, and serving as department chair from 2004 to 2011. Beginning in 2011 he was appointed the acting Dean, and then the Dean of the Kennedy College of Science at UML. At both UAA and UML, he won university awards for his research prowess.Mark was an internationally recognized leader in the field of microbial biogeochemistry. He published ~ 110 peer-reviewed journal articles and book chapters. The majority of these papers are published in the best geochemical and applied/environmental microbiological journals, including Global Biogeochemical Cycles, Applied and Environmental Microbiology, Applied Geochemistry, Chemical Geology, and Environmental Science and Technology. Fourteen (14) of his papers have over 100 citations, and his most highly cited paper "Anaerobic metabolism: linkages to trace gases and aerobic processes" in the 2003 Treatise on Geochemistry has 515 citations (Megonigal et al. 2003). One of his earliest papers, which came from his Ph.D. research, was a first author paper in Nature (Hines et al. 1982).Mark was one of the first to use radiolabeled sulfur to determine bacterial sulfate reduction rates in sediments and to quantify the different microbial pathways of methane

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The Effect of Bacterial Sulfate Reduction Inhibition on the Production and Stable Isotopic Composition of Methane in Hypersaline Environments

Cited by 4 publications

References 28 publications

Limitation of Microbial Processes at Saturation-Level Salinities in a Microbial Mat Covering a Coastal Salt Flat

Limitation of Microbial Processes at Saturation-Level Salinities in a Microbial Mat Covering a Coastal Salt Flat

Dissolved greenhouse gases and benthic microbial communities in coastal wetlands of the Chilean coast semiarid region

An Introduction to “Microbial Biogeochemistry: A Special Issue of Aquatic Geochemistry Honoring Mark Hines”

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