Carbon Isotope Fractionation by Sulfate-Reducing Bacteria Using Different Pathways for the Oxidation of Acetate

2008 ◽  
Vol 42 (21) ◽  
pp. 7813-7817 ◽  
Author(s):  
Dennis Goevert ◽  
Ralf Conrad
Keyword(s):  
Carbon Isotope ◽  
Isotope Fractionation ◽  
Sulfate Reducing Bacteria ◽  
Carbon Isotope Fractionation ◽  
Sulfate Reducing ◽  
Reducing Bacteria

scholarly journals Stable Carbon Isotope Fractionation by Sulfate-Reducing Bacteria

2003 ◽  
Vol 69 (5) ◽  
pp. 2942-2949 ◽  
Author(s):  
Kathleen L. Londry ◽  
David J. Des Marais
Keyword(s):  
Carbon Isotope ◽  
Isotope Fractionation ◽  
Carbon Isotope Discrimination ◽  
Stable Carbon Isotope ◽  
Reducing Power ◽  
Sulfate Reducing Bacteria ◽  
Organic Substrates ◽  
Isotope Discrimination ◽  
Sulfate Reducing ◽  
Reducing Bacteria

ABSTRACT Biogeochemical transformations occurring in the anoxic zones of stratified sedimentary microbial communities can profoundly influence the isotopic and organic signatures preserved in the fossil record. Accordingly, we have determined carbon isotope discrimination that is associated with both heterotrophic and lithotrophic growth of pure cultures of sulfate-reducing bacteria (SRB). For heterotrophic-growth experiments, substrate consumption was monitored to completion. Sealed vessels containing SRB cultures were harvested at different time intervals, and δ13C values were determined for gaseous CO2, organic substrates, and products such as biomass. For three of the four SRB, carbon isotope effects between the substrates, acetate or lactate and CO2, and the cell biomass were small, ranging from 0 to 2‰. However, for Desulfotomaculum acetoxidans, the carbon incorporated into biomass was isotopically heavier than the available substrates by 8 to 9‰. SRB grown lithoautotrophically consumed less than 3% of the available CO2 and exhibited substantial discrimination (calculated as isotope fractionation factors [α]), as follows: for Desulfobacterium autotrophicum, α values ranged from 1.0100 to 1.0123; for Desulfobacter hydrogenophilus, the α value was 0.0138, and for Desulfotomaculum acetoxidans, the α value was 1.0310. Mixotrophic growth of Desulfovibrio desulfuricans on acetate and CO2 resulted in biomass with a δ13C composition intermediate to that of the substrates. The extent of fractionation depended on which enzymatic pathways were used, the direction in which the pathways operated, and the growth rate, but fractionation was not dependent on the growth phase. To the extent that environmental conditions affect the availability of organic substrates (e.g., acetate) and reducing power (e.g., H2), ecological forces can also influence carbon isotope discrimination by SRB.

Sulfur isotope fractionation during growth of sulfate-reducing bacteria on various carbon sources

2004 ◽  
Vol 68 (23) ◽  
pp. 4891-4904 ◽  
Author(s):  
Jutta Kleikemper ◽  
Martin H. Schroth ◽  
Stefano M. Bernasconi ◽  
Benjamin Brunner ◽  
Josef Zeyer
Keyword(s):  
Isotope Fractionation ◽  
Sulfur Isotope ◽  
Carbon Sources ◽  
Sulfate Reducing Bacteria ◽  
Sulfate Reducing ◽  
Sulfur Isotope Fractionation ◽  
Reducing Bacteria

scholarly journals Carbon Isotope Fractionation during Anaerobic Degradation of Methyl tert-Butyl Ether under Sulfate-Reducing and Methanogenic Conditions

2006 ◽  
Vol 72 (2) ◽  
pp. 1157-1163 ◽  
Author(s):  
Piyapawn Somsamak ◽  
Hans H. Richnow ◽  
Max M. Häggblom
Keyword(s):  
Carbon Isotope ◽  
Anaerobic Degradation ◽  
Isotope Fractionation ◽  
Isotope Analysis ◽  
Methyl Tert Butyl Ether ◽  
Public Attention ◽  
Butyl Ether ◽  
Carbon Isotope Fractionation ◽  
Sulfate Reducing ◽  
Mtbe Degradation

ABSTRACT Methyl tert-butyl ether (MTBE), an octane enhancer and a fuel oxygenate in reformulated gasoline, has received increasing public attention after it was detected as a major contaminant of water resources. Although several techniques have been developed to remediate MTBE-contaminated sites, the fate of MTBE is mainly dependent upon natural degradation processes. Compound-specific stable isotope analysis has been proposed as a tool to distinguish the loss of MTBE due to biodegradation from other physical processes. Although MTBE is highly recalcitrant, anaerobic degradation has been demonstrated under different anoxic conditions and may be an important process. To accurately assess in situ MTBE degradation through carbon isotope analysis, carbon isotope fractionation during MTBE degradation by different cultures under different electron-accepting conditions needs to be investigated. In this study, carbon isotope fractionation during MTBE degradation under sulfate-reducing and methanogenic conditions was studied in anaerobic cultures enriched from two different sediments. Significant enrichment of 13C in residual MTBE during anaerobic biotransformation was observed under both sulfate-reducing and methanogenic conditions. The isotopic enrichment factors (ε) estimated for each enrichment were almost identical (−13.4 to −14.6; r 2 = 0.89 to 0.99). A ε value of −14.4 ± 0.7 was obtained from regression analysis (r 2 = 0.97, n = 55, 95% confidence interval), when all data from our MTBE-transforming anaerobic cultures were combined. The similar magnitude of carbon isotope fractionation in all enrichments regardless of culture or electron-accepting condition suggests that the terminal electron-accepting process may not significantly affect carbon isotope fractionation during anaerobic MTBE degradation.

The effect of temperature on sulfur and oxygen isotope fractionation by sulfate reducing bacteria (Desulfococcus multivorans)

2020 ◽  
Vol 367 (9) ◽  
Author(s):  
André Pellerin ◽  
Gilad Antler ◽  
Angeliki Marietou ◽  
Alexandra V Turchyn ◽  
Bo Barker Jørgensen
Keyword(s):  
Sulfate Reduction ◽  
Oxygen Isotope ◽  
Isotope Fractionation ◽  
Sulfur Isotope ◽  
Sulfate Reducing Bacteria ◽  
Oxygen Isotope Fractionation ◽  
Sulfate Reducing ◽  
Sulfur Isotope Fractionation ◽  
Reducing Bacteria ◽  
Desulfococcus Multivorans

ABSTRACT Temperature influences microbiological growth and catabolic rates. Between 15 and 35 °C the growth rate and cell specific sulfate reduction rate of the sulfate reducing bacterium Desulfococcus multivorans increased with temperature. Sulfur isotope fractionation during sulfate reduction decreased with increasing temperature from 27.2 ‰ at 15 °C to 18.8 ‰ at 35 °C which is consistent with a decreasing reversibility of the metabolic pathway as the catabolic rate increases. Oxygen isotope fractionation, in contrast, decreased between 15 and 25 °C and then increased again between 25 and 35 °C, suggesting increasing reversibility in the first steps of the sulfate reducing pathway at higher temperatures. This points to a decoupling in the reversibility of sulfate reduction between the steps from the uptake of sulfate into the cell to the formation of sulfite, relative to the whole pathway from sulfate to sulfide. This observation is consistent with observations of increasing sulfur isotope fractionation when sulfate reducing bacteria are living near their upper temperature limit. The oxygen isotope decoupling may be a first signal of changing physiology as the bacteria cope with higher temperatures.

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