Fractionation of sulfur isotopes by continuous cultures of Desulfovibrio desulfuricans

1975 ◽  
Vol 21 (10) ◽  
pp. 1602-1607 ◽  
Author(s):  
Lyn A. Chambers ◽  
Philip A. Trudinger ◽  
John W. Smith ◽  
Maurice S. Burns

Sulfur isotope effects observed in lactate-limited continuous cultures of Desulfovibrio desulfuricans were, in general, similar to those reported for sulfate reduction by washed cells and batch cultures. There was a trend towards higher fractionation at low growth rates.

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.


2018 ◽  
Vol 115 (34) ◽  
pp. 8541-8546 ◽  
Author(s):  
Mang Lin ◽  
Xiaolin Zhang ◽  
Menghan Li ◽  
Yilun Xu ◽  
Zhisheng Zhang ◽  
...  

The signature of mass-independent fractionation of quadruple sulfur stable isotopes (S-MIF) in Archean rocks, ice cores, and Martian meteorites provides a unique probe of the oxygen and sulfur cycles in the terrestrial and Martian paleoatmospheres. Its mechanistic origin, however, contains some uncertainties. Even for the modern atmosphere, the primary mechanism responsible for the S-MIF observed in nearly all tropospheric sulfates has not been identified. Here we present high-sensitivity measurements of a fifth sulfur isotope, stratospherically produced radiosulfur, along with all four stable sulfur isotopes in the same sulfate aerosols and a suite of chemical species to define sources and mechanisms on a field observational basis. The five-sulfur-isotope and multiple chemical species analysis approach provides strong evidence that S-MIF signatures in tropospheric sulfates are concomitantly affected by two distinct processes: an altitude-dependent positive 33S anomaly, likely linked to stratospheric SO2 photolysis, and a negative 36S anomaly mainly associated with combustion. Our quadruple stable sulfur isotopic measurements in varying coal samples (formed in the Carboniferous, Permian, and Triassic periods) and in SO2 emitted from combustion display normal 33S and 36S, indicating that the observed negative 36S anomalies originate from a previously unknown S-MIF mechanism during combustion (likely recombination reactions) instead of coal itself. The basic chemical physics of S-MIF in both photolytic and thermal reactions and their interplay, which were not explored together in the past, may be another ingredient for providing deeper understanding of the evolution of Earth’s atmosphere and life’s origin.


2015 ◽  
Author(s):  
William D. Leavitt ◽  
Alexander S. Bradley ◽  
André A. Santos ◽  
Inês A.C. Pereira ◽  
David T. Johnston

The precise interpretation of environmental sulfur isotope records requires a quantitative understanding of the biochemical controls on sulfur isotope fractionation by the principle isotope-fractionating process within the S cycle, microbial sulfate reduction (MSR). Here we provide the only direct observation of the major (34S/32S) and minor (33S/32S,36S/32S) sulfur isotope fractionations imparted by a central enzyme in the energy metabolism of sulfate reducers, dissimilatory sulfite reductase (DsrAB). Results from in vitro sulfite reduction experiments allow us to calculate the in vitro DsrAB isotope effect in34S/32S (hereafter,34ϵDsrAB) to be 15.3±2‰, 2σ. The accompanying minor isotope effect in33S, described as33λDsrAB, is calculated to be 0.5150±0.0012, 2σ. These observations facilitate a rigorous evaluation of the isotopic fractionation associated with the dissimilatory MSR pathway, as well as of the environmental variables that govern the overall magnitude of fractionation by natural communities of sulfate reducers. The isotope effect induced by DsrAB upon sulfite reduction is a factor of 0.3 to 0.6 times prior indirect estimates, which have ranged from 25 to 53‰ in34ϵDsrAB. The minor isotope fractionation observed from DsrAB is consistent with a kinetic or equilibrium effect. Our in vitro constraints on the magnitude of34ϵDsrABis similar to the median value of experimental observations compiled from all known published work, where34ϵr-p= 16.1‰ (r – pindicates reactant versus product, n = 648). This value closely matches those of MSR operating at high sulfate reduction rates in both laboratory chemostat experiments (34ϵSO4-H2S= 17.3±1.5‰) and in modern marine sediments (34ϵSO4-H2S= 17.3±3.8‰). Targeting the direct isotopic consequences of a specific enzymatic processes is a fundamental step toward a biochemical foundation for reinterpreting the biogeochemical and geobiological sulfur isotope records in modern and ancient environments.


1972 ◽  
Vol 26 ◽  
pp. 573-580 ◽  
Author(s):  
Trygve E. Eriksen ◽  
Olav Vikane ◽  
Carl-Gunnar Swahn ◽  
R. Larsson ◽  
B. Nordén ◽  
...  

1972 ◽  
Vol 26 ◽  
pp. 581-584 ◽  
Author(s):  
Trygve E. Eriksen ◽  
Olav Vikane ◽  
Carl-Gunnar Swahn ◽  
R. Larsson ◽  
B. Nordén ◽  
...  

Science ◽  
2019 ◽  
Vol 364 (6438) ◽  
pp. 383-385 ◽  
Author(s):  
Karen V. Smit ◽  
Steven B. Shirey ◽  
Erik H. Hauri ◽  
Richard A. Stern

Neoproterozoic West African diamonds contain sulfide inclusions with mass-independently fractionated (MIF) sulfur isotopes that trace Archean surficial signatures into the mantle. Two episodes of subduction are recorded in these West African sulfide inclusions: thickening of the continental lithosphere through horizontal processes around 3 billion years ago and reworking and diamond growth around 650 million years ago. We find that the sulfur isotope record in worldwide diamond inclusions is consistent with changes in tectonic processes that formed the continental lithosphere in the Archean. Slave craton diamonds that formed 3.5 billion years ago do not contain any MIF sulfur. Younger diamonds from the Kaapvaal, Zimbabwe, and West African cratons do contain MIF sulfur, which suggests craton construction by advective thickening of mantle lithosphere through conventional subduction-style horizontal tectonics.


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