Stable isotope fractionation by Clostridium pasteurianum. 1.34S/32S: inverse isotope effects during SO42− and SO32− reduction

1975 ◽  
Vol 21 (3) ◽  
pp. 235-244 ◽  
Author(s):  
R. G. L. McCready ◽  
E. J. Laishley ◽  
H. R. Krouse
Keyword(s):  
Isotope Fractionation ◽  
Isotope Effects ◽  
Sulfite Reductase ◽  
Clostridium Pasteurianum ◽  
Stages Of Growth ◽  
Dissimilatory Sulfite Reductase ◽  
Stable Isotope Fractionation ◽  
High Concentrations ◽  
Late Stages ◽  
Isotopic Effects

During growth on minimal salts – sucrose media supplemented with various concentrations (10−4–10−2 M) of sodium sulfate, Clostridium pasteurianum grew at a normal rate and only evolved sulfide in late stages of growth on 10−2 M SO42−. The evolved sulfide was slightly enriched in 34S as compared to the medium sulfur. On the other hand, sulfide was evolved during growth on all concentrations of sulfite tested. Large normal and inverse isotopic effects were observed in the evolved sulfide during SO32− reductions. In contrast, the intracellular sulphur showed much smaller fractionations. The complexity of the isotopic patterns suggests that a dissimilatory sulfite reductase system may be induced by high concentrations of sulfite.

Thiosulfate formation and associated isotope effects during sulfite reduction by Clostridium pasteurianum

1979 ◽  
Vol 25 (6) ◽  
pp. 719-721 ◽  
Author(s):  
L. A. Chambers ◽  
P. A. Trudinger
Keyword(s):  
Isotope Fractionation ◽  
Sulfur Isotope ◽  
Isotope Effects ◽  
Clostridium Pasteurianum ◽  
Stages Of Growth ◽  
Bacterial Cultures ◽  
Sulfur Isotope Fractionation ◽  
Secondary Chemical Reaction ◽  
Secondary Chemical ◽  
Isotopic Effects

During growth of Clostridium pasteurianum on sulfite, approximately half the sulfite was reduced to sulfide and half to thiosulfate. Sulfide was enriched in 32S or 34S at different stages of growth and thiosulfate was enriched in 32S, particularly in the sulfane atom.It is suggested that thiosulfate in these bacterial cultures arose from a secondary chemical reaction. The chemical formation of thiosulfate from sulfide and sulfite was also accompanied by sulfur isotope fractionation. The implications of these results with respect to 'inverse' isotopic effects are discussed.

Stable isotope fractionation by Clostridium pasteurianum. 4. Sulfur isotope fractionation during enzymatic S3O62−, S2O32−, and SO32− reductions

1981 ◽  
Vol 27 (8) ◽  
pp. 824-834
Author(s):  
G. I. Harrison ◽  
E. J. Laishley ◽  
H. R. Krouse
Keyword(s):  
Stable Isotope ◽  
Isotope Fractionation ◽  
Sulfur Isotope ◽  
Isotope Effects ◽  
Growth Conditions ◽  
Enzyme Concentration ◽  
Clostridium Pasteurianum ◽  
Relative Reduction ◽  
Stable Isotope Fractionation ◽  
Sulfur Isotope Fractionation

Cell-free extracts from Clostridium pasteurianum grown on SO32− utilize H2 to reduce S3O62−, S2O32−, and SO32− to H2S at a much faster rate than extracts from SO42−-grown cells. This further supports the concept of an inducible dissimilatory type SO32− reductive pathway in this organism. 35S dilution experiments further support the concept that S3O62− and S2O32− are pathway intermediates. The inducible SO32− reductase is ferredoxin linked and the kinetics of the reduction and the sulfur isotope fractionation of the product can be altered by altering the growth conditions. The attending sulfur isotope fractionations are similar to those observed during the chemical decomposition of these compounds. In the case of S2O32−, 35S labelling experiments verified the conclusions derived from the stable isotope fractionation data concerning the relative reduction rates of the sulfane and sulfonate sulfurs. The reduction rates were also affected by enzyme concentration. The integrity of the whole cell is a necessary requirement for the large inverse isotope effects previously reported.

Stable isotope fractionation by Clostridium pasteurianum. 2. Regulation of sulfite reductases by sulfur amino acids and their influence on sulfur isotope fractionation during SO32− and SO42− reduction

1978 ◽  
Vol 24 (6) ◽  
pp. 716-724 ◽  
Author(s):  
E. J. Laishley ◽  
H. R. Krouse
Keyword(s):  
Amino Acids ◽  
Isotope Fractionation ◽  
Sulfur Isotope ◽  
Sulfite Reductase ◽  
Clostridium Pasteurianum ◽  
Sulfur Amino Acids ◽  
Stable Isotope Fractionation ◽  
Sulfur Isotope Fractionation ◽  
Sulfide Production ◽  
Logarithmic Growth

In addition to an assimilatory sulfite reductase, studies of cultures of Clostridium pasteurianum supplemented with methionine, cysteine, and 35SO42− provide evidence for another reductase which is induced by SO32−. This inducible reductase appears to be dissimilatory because of the copious sulfide production arising when the cells are grown on SO32−. Cysteine can repress the assimilatory sulfite reductase but does not affect the inducible reductase. During late logarithmic growth on 1 mM SO42− + 10 mM cysteine, derepression of the inducible reductase occurred along with increased sulfide production. The presence of 1 mM cysteine and (or) 1 mM methionine does not affect the inverse sulfur isotope effect for evolved H2S. However, 5 and 10 mM cysteine reduce the maximum δ34S value for released H2S from +40 to +10‰. A small conversion of cysteine to H2S by C. pasteurianum occurs, but only in the stationary phase.

scholarly journals Sulfur Isotope Effects of Dissimilatory Sulfite Reductase

2015 ◽  
Author(s):  
William D. Leavitt ◽  
Alexander S. Bradley ◽  
André A. Santos ◽  
Inês A.C. Pereira ◽  
David T. Johnston
Keyword(s):  
Sulfate Reduction ◽  
Isotope Effect ◽  
Isotope Fractionation ◽  
Sulfur Isotope ◽  
Isotope Effects ◽  
Isotopic Fractionation ◽  
Sulfite Reductase ◽  
Sulfate Reducers ◽  
Dissimilatory Sulfite Reductase

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.

scholarly journals Unravelling the process of petroleum hydrocarbon biodegradation in different filter materials of constructed wetlands by stable isotope fractionation and labelling studies

2021 ◽  
Author(s):  
Andrea Watzinger ◽  
Melanie Hager ◽  
Thomas Reichenauer ◽  
Gerhard Soja ◽  
Paul Kinner
Keyword(s):  
Stable Isotope ◽  
Constructed Wetlands ◽  
Hydrogen Isotope ◽  
Petroleum Hydrocarbon ◽  
Isotope Fractionation ◽  
Isotope Effects ◽  
Filter Material ◽  
Hydrocarbon Biodegradation ◽  
Stable Isotope Fractionation ◽  
Filter Materials

AbstractMaintaining and supporting complete biodegradation during remediation of petroleum hydrocarbon contaminated groundwater in constructed wetlands is vital for the final destruction and removal of contaminants. We aimed to compare and gain insight into biodegradation and explore possible limitations in different filter materials (sand, sand amended with biochar, expanded clay). These filters were collected from constructed wetlands after two years of operation and batch experiments were conducted using two stable isotope techniques; (i) carbon isotope labelling of hexadecane and (ii) hydrogen isotope fractionation of decane. Both hydrocarbon compounds hexadecane and decane were biodegraded. The mineralization rate of hexadecane was higher in the sandy filter material (3.6 µg CO2 g−1 day−1) than in the expanded clay (1.0 µg CO2 g−1 day−1). The microbial community of the constructed wetland microcosms was dominated by Gram negative bacteria and fungi and was specific for the different filter materials while hexadecane was primarily anabolized by bacteria. Adsorption / desorption of petroleum hydrocarbons in expanded clay was observed, which might not hinder but delay biodegradation. Very few cases of hydrogen isotope fractionation were recorded in expanded clay and sand & biochar filters during decane biodegradation. In sand filters, decane was biodegraded more slowly and hydrogen isotope fractionation was visible. Still, the range of observed apparent kinetic hydrogen isotope effects (AKIEH = 1.072–1.500) and apparent decane biodegradation rates (k = − 0.017 to − 0.067 day−1) of the sand filter were low. To conclude, low biodegradation rates, small hydrogen isotope fractionation, zero order mineralization kinetics and lack of microbial biomass growth indicated that mass transfer controlled biodegradation.

Stable isotope fractionation by Clostridium pasteurianum. 5. Effect of SeO42− on the physiology and associated sulfur isotope fractionation during SO32− and SO42− reductions

1982 ◽  
Vol 28 (3) ◽  
pp. 325-333 ◽  
Author(s):  
G. I. Harrison ◽  
E. J. Laishley ◽  
H. R. Krouse
Keyword(s):  
Stationary Phase ◽  
Isotope Fractionation ◽  
Sulfur Isotope ◽  
Reductase Activity ◽  
Clostridium Pasteurianum ◽  
Elemental Selenium ◽  
Whole Cells ◽  
Stable Isotope Fractionation ◽  
Sulfur Isotope Fractionation ◽  
Inverse Isotope Effect

The addition of 1 mM SeO42− significantly affected the physiology and metabolism of Clostridium pasteurianum growing on SO42− in the following ways: (1) the generation time was increased, essentially producing a biphasic growth curve, (2) cells became elongated and chains formed, (3) no H2S was liberated during the stationary phase, (4) assimilatory SO32− reductase activity was decreased, (5) ferredoxin levels decreased by a factor of 4. The effects of 1 mM SeO42− on Clostridium pasteurianum growing on SO32− were comparatively minor.H2S evolution in the stationary phase decreased by a factor of 2 and the δ34S maximum in the inverse isotope effect pattern occurred at a slightly lower percent H2S evolution. The deleterious effects of SeO42− addition were less pronounced than those associated with SeO32− addition. SeO32− but not SeO42− was reduced to elemental selenium by both whole cells and crude extracts.

scholarly journals Nitrogen isotope dynamics and fractionation during sedimentary denitrification in Boknis Eck, Baltic Sea

2013 ◽  
Vol 10 (1) ◽  
pp. 681-709 ◽  
Author(s):  
K. Dähnke ◽  
B. Thamdrup
Keyword(s):  
Baltic Sea ◽  
Water Column ◽  
Isotope Fractionation ◽  
Isotope Effects ◽  
Nitrogen Isotope ◽  
Current View ◽  
Underlying Assumption ◽  
Stable Isotope Fractionation ◽  
Seasonal Hypoxia ◽  
Preferential Uptake

Abstract. The global marine nitrogen cycle is constrained by nitrogen fixation as a source of reactive nitrogen, and denitrification or anammox on the sink side. These processes with their respective isotope effects set the marine nitrate 15N-isotope value (δ15N) to a relatively constant average of 5‰. This value can be used to better assess the magnitude of these sources and sink terms, but the underlying assumption is that sedimentary denitrification and anammox, processes responsible for approximately one third of global nitrogen removal, have little to no isotope effect on nitrate in the water column. We investigated the isotope fractionation in sediment incubations, measuring net denitrification and nitrogen and oxygen stable isotope fractionation in surface sediments from the coastal Baltic Sea (Boknis Eck, Northern Germany), a site with seasonal hypoxia and dynamic nitrogen turnover. We found tremendously high denitrification rates, and regardless of current paradigms assuming little fractionation during sediment denitrification, we measured fractionation factors of 18.9‰ for nitrogen and 15.8‰ for oxygen in nitrate. While the input of nitrate to the water column remains speculative, these results challenge the current view of fractionation during sedimentary denitrification and imply that nitrogen budget calculations may need to consider this variability, as both preferential uptake of light nitrate and release of the remaining heavy fraction can significantly alter water column nitrate isotope vales at the sediment-water interface.

scholarly journals Nitrogen isotope dynamics and fractionation during sedimentary denitrification in Boknis Eck, Baltic Sea

2013 ◽  
Vol 10 (5) ◽  
pp. 3079-3088 ◽  
Author(s):  
K. Dähnke ◽  
B. Thamdrup
Keyword(s):  
Baltic Sea ◽  
Water Column ◽  
Isotope Fractionation ◽  
Isotope Effects ◽  
Nitrogen Isotope ◽  
Current View ◽  
Underlying Assumption ◽  
Stable Isotope Fractionation ◽  
Seasonal Hypoxia ◽  
Sediment Denitrification

Abstract. The global marine nitrogen cycle is constrained by nitrogen fixation as a source of reactive nitrogen, and denitrification or anammox on the sink side. These processes with their respective isotope effects set the marine nitrate 15N-isotope value (δ15N) to a relatively constant average of 5‰. This value can be used to better assess the magnitude of these sources and sink terms, but the underlying assumption is that sedimentary denitrification and anammox, processes responsible for approximately one-third of global nitrogen removal, have little to no isotope effect on nitrate in the water column. We investigated the isotope fractionation in sediment incubations, measuring net denitrification and nitrogen and oxygen stable isotope fractionation in surface sediments from the coastal Baltic Sea (Boknis Eck, northern Germany), a site with seasonal hypoxia and dynamic nitrogen turnover. Sediment denitrification was fast, and regardless of current paradigms assuming little fractionation during sediment denitrification, we measured fractionation factors of 18.9‰ for nitrogen and 15.8‰ for oxygen in nitrate. While the input of nitrate to the water column remains speculative, these results challenge the current view of fractionation during sedimentary denitrification and imply that nitrogen budget calculations may need to consider this variability, as both preferential uptake of light nitrate and release of the remaining heavy fraction can significantly alter water column nitrate isotope values at the sediment–water interface.

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