Conversion of 13C-1 phenol to 13C-4 benzoate, an intermediate step in the anaerobic degradation of chlorophenols

13C-1 phenol was converted to 13C-4 benzoic acid by an anaerobic phenol converting enrichment, which did not form p-hydroxybenzoate as a free intermediate but converted p-hydroxybenzoate first phenol and then, probably by another organism, to benzoate. No isotopic effect was observed using D5- and D6-phenol, suggesting that the breakage of the C-H bond on the C-4 position was not a rate limiting step in the conversion.