The isomerization of butyrate and isobutyrate was investigated for the sulfate reducer Desulforhabdus amnigenus. Nuclear magnetic resonance (NMR) studies with 13C-labelled butyrate showed that isobutyrate was formed by migration of the carboxyl group, in conformity with the butyrate isomerization reaction reported for methanogenic consortia. In addition to D. amnigenus, several other butyrate-degrading sulfate reducers (Desulfobacterium vacuolatum, Desulfoarculus baarsii and Desulfotomaculum sp.) were capable of butyrate isomerization.
Oude Elferink, S. J. W. H., Lens, P. N. L., Dijkema, C., & Stams, A. J. M. (1996). Isomerization of butyrate to isobutyrate by Desulforhabdus amnigenus. FEMS Microbiology Letters, 142(2–3), 237–241. https://doi.org/10.1016/0378-1097(96)00274-1