Demethylation of Ferulic Acid and Feruloyl-arabinoxylan by Microbial Cell Extracts

The O -demethylation of ferulic acid and feruloyl-arabinoxylan by the anaerobic bacteria Clostridium methoxybenzovorans (strain SR3) and the facultative aerobic bacteria Enterobacter cloacae (strain DG6) was investigated in order to produce caffeic acid and caffeoyl-arabinoxylan. As both strains produced endocellular enzymes, disrupted cell extracts from these two bacteria were prepared and tested. The SR3-disrupted cell extract was able to produce caffeic acid from free ferulic acid with 84% yield. The use of cysteine as reducing agent in the reaction medium stabilised the highly reactive caffeic acid produced. The DG6-disrupted cell extract used ferulic acid but no caffeic acid was detected, suggesting that it was only an intermediary product of the reaction. None of the two disrupted cell extracts were able to O-demethylate feruloyl-arabinoxylans.