REVERSIBLE CONVERSION OF 4-HYDROXYBENZOATE AND PHENOL BY CLOSTRIDIUM-HYDROXYBENZOICUM

Reversible conversion of 4-hydroxybenzoate and phenol and their analogs was observed in whole cell suspensions and cell extracts of Clostridium hydroxybenzoicum grown with 4-hydroxybenzoate and 3,4-dihydroxybenzoate. Assuming that bicarbonate is the cosubstrate, the equilibrium constants calculated for the reactions 4-hydroxybenzoate(-) + H2O reversible arrow phenol + HCO3- and 3,4-dihydroxybenzoate(-) + H2O reversible arrow catechol + HCO3- were 11.4 (+/- 0.5) and 5.05 (+/- 0.25), respectively. In a phenol-adapted sediment slurry, 4-hydroxy-benzoate and 3,4-dihydroxybenzoate were decarboxylated to phenol and to catechol, respectively, as intermediates without a lag time.