Metabolism of sulfonic acids and other organosulfur compounds by sulfate-reducing bacteria

This article presents a short review of recent research that established the ability of sulfate-reducing bacteria to utilize sulfonic acids as terminal electron accepters (TEA) for anaerobic respiratory growth. Newer studies of the bacterium most intensively investigated, Desulfovibrio desulfuricans, strain ICI, are also reported. When either of two sulfonic acids examined-isethionate (2-hydroxyethanesulfonate) or cysteate (alanine-3-sulfonate)-served as sole TEA, key changes in the cells' enzymological profile occurred: decreased production of two enzymes involved in sulfate reduction, namely, ATP sulfurylase and APS reductase. Similar reduction in content of these enzymes was seen when either sulfite or fumarate served as TEA. Protein profiles (polyacrylamide gel electrophoresis) of extracts of cells grown with different TEA revealed the presence of a 97-kD polypeptide apparently unique to isethionate-grown cells; a different polypeptide was noted in extracts of cysteate-grown cells. The absence of such stained bands in extracts of sulfate-grown cells suggests that these polypeptides are involved in utilization of sulfonic acids as TEA. H-2 threshold values of cells growth with isethionate as TEA were significantly lower than for cells growing with sulfate or sulfite, suggesting that energy may be conserved in the cleavage of isethionate's C-S linkage. A survey of the distribution of sulfonic acids in diverse habitats combined with the ability of other anaerobic bacteria to respire these compounds leads to the suggestion sulfonate reduction is likely to be significant in the sulfur cycle.