Open AccessStable sulfur isotope fractionation and discrimination between the sulfur atoms of thiosulfate during oxidation by Halothiobacillus neapolitanus
Author(s) -
Kelly Donovan P.
Publication year - 2008
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2008.01146.x
Subject(s) - thiosulfate , sulfur , chemistry , δ34s , sulfate , isotope fractionation , isotopes of sulfur , sulfite , inorganic chemistry , fractionation , organic chemistry , biochemistry , geology , paleontology , quartz , amino acid , methionine , fluid inclusions
Growing cultures and nongrowing suspensions of Halothiobacillus neapolitanus selectively fractionated 32 S and 34 S during the oxidation of the sulfane‐ and sulfonate‐sulfur atoms of thiosulfate. Sulfate was enriched in 32 S, with δ 34 S reaching −6.3‰ relative to the precursor sulfonate‐sulfur of thiosulfate, which was progressively resynthesized from the thiosulfate‐sulfane‐sulfur during thiosulfate metabolism. Polythionates, principally trithionate, accumulated during thiosulfate oxidation and showed progressive increase in the relative 34 S content of their sulfonate groups, with δ 34 S values up to +20‰, relative to the substrate sulfur. The origins of the sulfur in the sulfate and polythionate products of oxidation were tracked by the use thiosulfate labelled with 35 S in each of its sulfur atoms, enabling determination of the flow of the sulfur atoms into the oxidation products. The results confirm that highly significant fractionation of stable sulfur isotopes can be catalyzed by thiobacilli oxidizing thiosulfate, but that differences in the 34 S/ 32 S ratios of the nonequivalent constituent sulfur atoms of the thiosulfate used as substrate mean that the oxidative fate of each atom needs separate determination. The data are very significant to the understanding of bacterial sulfur‐compound oxidation and highly relevant to the origins of biogenic sulfate minerals.