THE ROLE OF A METABOLIC INTERMEDIATE IN THE BIODEGRADATION OF INHIBITORY SUBSTRATES

Biodegradation of the mixed inhibitory substrates, 2,4-dichlorophenoxy acetic acid (2,4-D) and para-chloro-ortho-cresol (PCOC) was studied in aerobic batch cultures. Each substrate added beyond certain concentra tions inhibited the degradation of the other. This mutual inhibition w as found to be enhanced by 2,4-dichlorophenol (2,4-DCP) which is an in termediate metabolic product of 2,4-D. When 2,4-DCP accumulated to app roximately 40 mg/l degradation of all compounds in the mixed 2,4-D and PCOC substrate system was completely inhibited. The degradation of 2, 4-D and PCOC individually was also found to be inhibited by elevated c oncentrations of 2,4-DCP added externally, while PCOC inhibited the ut ilization of the intermediate. (C) 1997 IAWQ. Published by Elsevier Sc ience Ltd.