scholarly journals Using kinetic isotope effect to evaluate the significance of the sequential and parallel steps: formation of microbial consortium during reversible anaerobic methane oxidation coupled with sulfate reduction

2019 ◽  
Vol 79 (11) ◽  
pp. 2056-2067
Author(s):  
Vasily Vavilin ◽  
Lyudmila Lokshina ◽  
Sergey Rytov

Abstract The purpose of this study was to describe the dynamics of anaerobic oxidation of methane (AOM) coupled with sulfate reduction (SR) using experimental data from a continuous incubation experiments published earlier in order to show that formation of consortia of anaerobic archaea (ANME) and Desulfosarcina-like bacteria (DSS) may have a significant effect on sulfur isotope fractionation. The dynamic simulation of reversible AOM by ANME coupled with SR by DSS was performed. This simulation took into account biomass growth and fractionation of stable isotopes of sulfur. Two kinetic schemes with and without ANME + DSS consortium formation were tested. The respective models were applied at five influent methane concentrations. A good fit to experimental data was obtained only when assuming active ANME and DSS biomass accumulation. The assumption about incorporation of reversibility of anaerobic methane oxidation and sulfate reduction did not improve the model's fit to experimental data. In accordance with both the models, sulfur isotope fractionation was smallest for the highest influent methane concentration. The model considering the formation of consortia of ANME + DSS is proved to be more appropriate.

1979 ◽  
Vol 25 (10) ◽  
pp. 1139-1144 ◽  
Author(s):  
R. G. L. McCready ◽  
G. A. Din ◽  
H. R. Krouse

Growth of Saccharomyces cerevisiae in minimal salts – glucose – SO42− medium with varying concentrations of pantothenate (0–1000 μg/L) produced changes in the cellular lipid content and in the ratio of saturated to unsaturated fatty acids. Substantial differences in SO42−diffusion were also observed with changes in pantothenate concentration. During sulfate reduction, the δ34S value of the evolved sulfide varied with the pantothenate concentration ranging from −31‰ in the absence of pantothenate to 0‰ at 400−1000 μg/L pantothenate. The isotope selectivity is related to the effect of pantothenate concentration on cellular metabolism.


2001 ◽  
Vol 67 (2) ◽  
pp. 888-894 ◽  
Author(s):  
Jan Detmers ◽  
Volker Brüchert ◽  
Kirsten S. Habicht ◽  
Jan Kuever

ABSTRACT Batch culture experiments were performed with 32 different sulfate-reducing prokaryotes to explore the diversity in sulfur isotope fractionation during dissimilatory sulfate reduction by pure cultures. The selected strains reflect the phylogenetic and physiologic diversity of presently known sulfate reducers and cover a broad range of natural marine and freshwater habitats. Experimental conditions were designed to achieve optimum growth conditions with respect to electron donors, salinity, temperature, and pH. Under these optimized conditions, experimental fractionation factors ranged from 2.0 to 42.0‰. Salinity, incubation temperature, pH, and phylogeny had no systematic effect on the sulfur isotope fractionation. There was no correlation between isotope fractionation and sulfate reduction rate. The type of dissimilatory bisulfite reductase also had no effect on fractionation. Sulfate reducers that oxidized the carbon source completely to CO2 showed greater fractionations than sulfate reducers that released acetate as the final product of carbon oxidation. Different metabolic pathways and variable regulation of sulfate transport across the cell membrane all potentially affect isotope fractionation. Previous models that explained fractionation only in terms of sulfate reduction rates appear to be oversimplified. The species-specific physiology of each sulfate reducer thus needs to be taken into account to understand the regulation of sulfur isotope fractionation during dissimilatory sulfate reduction.


Geobiology ◽  
2015 ◽  
Vol 14 (1) ◽  
pp. 91-101 ◽  
Author(s):  
A. S. Bradley ◽  
W. D. Leavitt ◽  
M. Schmidt ◽  
A. H. Knoll ◽  
P. R. Girguis ◽  
...  

2012 ◽  
Vol 78 (23) ◽  
pp. 8368-8376 ◽  
Author(s):  
Min Sub Sim ◽  
Shuhei Ono ◽  
Tanja Bosak

ABSTRACTSulfate-reducing microbes utilize sulfate as an electron acceptor and produce sulfide that is depleted in heavy isotopes of sulfur relative to sulfate. Thus, the distribution of sulfur isotopes in sediments can trace microbial sulfate reduction (MSR), and it also has the potential to reflect the physiology of sulfate-reducing microbes. This study investigates the relationship between the availability of iron and reduced nitrogen and the magnitude of S-isotope fractionation during MSR by a marine sulfate-reducing bacterium, DMSS-1, aDesulfovibriospecies, isolated from salt marsh in Cape Cod, MA. Submicromolar levels of iron increase sulfur isotope fractionation by about 50% relative to iron-replete cultures of DMSS-1. Iron-limited cultures also exhibit decreased cytochromec-to-total protein ratios and cell-specific sulfate reduction rates (csSRR), implying changes in the electron transport chain that couples carbon and sulfur metabolisms. When DMSS-1 fixes nitrogen in ammonium-deficient medium, it also produces larger fractionation, but it occurs at faster csSRRs than in the ammonium-replete control cultures. The energy and reducing power required for nitrogen fixation may be responsible for the reverse trend between S-isotope fractionation and csSRR in this case. Iron deficiency and nitrogen fixation by sulfate-reducing microbes may lead to the large observed S-isotope effects in some euxinic basins and various anoxic sediments.


2012 ◽  
Vol 46 (16) ◽  
pp. 8895-8902 ◽  
Author(s):  
Jennifer L. Druhan ◽  
Carl I. Steefel ◽  
Sergi Molins ◽  
Kenneth H. Williams ◽  
Mark E. Conrad ◽  
...  

2012 ◽  
Vol 9 (4) ◽  
pp. 4919-4945
Author(s):  
A. Bannert ◽  
C. Bogen ◽  
J. Esperschütz ◽  
A. Koubová ◽  
F. Buegger ◽  
...  

Abstract. While the importance of anaerobic methane oxidation has been reported for marine ecosystems, the role of this process in soils is still questionable. Grasslands used as pastures for cattle-overwintering show an increase in anaerobic soil micro-sites caused by animal treading and excrement deposition. Therefore anaerobic potential methane oxidation activity of severely impacted soil from a cattle winter pasture was investigated in an incubation experiment under anaerobic conditions using 13C-labeled methane. We were able to detect a high microbial activity utilizing CH4 as nutrient source shown by the respiration of 13CO2. Measurements of possible terminal electron acceptors for anaerobic oxidation of methane were carried out. Soil sulfate concentrations were too low to explain the oxidation of the amount of methane added, but enough nitrate and iron(III) were detected. However, only nitrate was consumed during the experiment. 13C-PLFA analyses clearly showed the utilization of CH4 as nutrient source mainly by organisms harbouring 16:1ω7 PLFAs. These lipids were found in Gram-negative microorganisms and anaerobes. The fact that these lipids are also typical for type I methanotrophs, known as aerobic methane oxidizers, might indicate a link between aerobic and anaerobic methane oxidation.


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