FERMENTATION OF CYSTEATE BY A SULFATE-REDUCING BACTERIUM

We isolated a strictly anaerobic bacterium, strain GRZCYSA, from a slu dge digestor for its ability to ferment cysteate (2-amino-3-sulfopropi onate). The organism also fermented the organosulfonates isethionate ( 2-hydroxyethanesulfonate) and aminomethanesulfonate, but taurine (2-am inoethanesulfonate) was not a substrate. Strain GRZCYSA, a gram-negati ve, oxidase-negative and catalase-positive vibrio that could reduce su lfate and contained desulfoviridin, was tentatively identified as Desu lfovibrio sp. Utilization of cysteate as a substrate for fermentative growth led to the formation of four products identified as acetate, am monia, and equimolar amounts of sulfide and sulfate. The fermentation was in balance. Some reactions involved in this novel process were det ected in cell-free extracts in which ammonia and acetate were formed f rom cysteate.