Metabolism of cinnamic acids by some Clostridiales and emendation of the descriptions of Clostridium aerotolerans, Clostridium celerecrescens and Clostridium xylanolyticum

The ability of Clostridium aerotolerans DSM 5434(T), Clostridium celerecrescens DSM 5628(T), Clostridium methoxybenzovorans DSM 12182(T), Clostridium stercorarium ATCC 35414(T), Clostridium subterminale DSM 2636, Clostridium termitidis DSM 5398(T), Clostridium thermolacticum DSM 2910(T), Clostridium thermopalmarium DSM 5974(T) and Clostridium xylanolyticum DSM 6555(T) to metabolize cinnamic acid and various derivatives, with or without glucose supplementation, was examined. Only C. aerotolerans DSM 5434T and C. xylanolyticum DSM 6555T, closely related species, transformed cinnamic acid to 3-phenylpropionic acid. Both species also reduced a wide range of cinnamic acid derivatives, including o-, m- and p-coumaric, o-, m- and p-methoxycinnamic, p-methylcinnamic, caffeic, ferulic, isoferulic and 3,4,5-trimethoxycinnamic acids to their corresponding 3-phenylpropionic acid derivatives. C. aerotolerans DSM 5434T, however, also decarboxylated p-coumaric acid into 4-vinylphenol, which was then reduced to 4-ethylphenol. C. celerecrescens was grouped with C. aerotolerans and C. xylanolyticum in subcluster XIVa of the Clostridiales. C. celerecrescens DSM 5628T only metabolized m- and p-methoxycinnamic and p-methylcinnamic acids to their corresponding 3-phenylpropionic acid derivatives, reducing the double bond in the C-3 aliphatic side chair. Addition of glucose markedly increased the yield of the biotransformations by these three species. An emendation of the descriptions of C. aerotolerans, C. celerecrescens and C. xylanolyticum is proposed, based on these observations.