AN ATTEMPT TO CONTROL THE POLYCHLOROCATECHOL PIGMENT PRODUCTION DURING 3-CHLOROBENZOATE AEROBIC CO-METABOLISM IN GROWING-CELL BATCH CULTURE

A strain of Pseudomonas fluorescens, designed CP30, was capable of co- metabolizing 3-chlorobenzoic acid via chlorocatechols, thus producing a polychlorocatechol black pigment. The pigment production was found t o be enzyme-mediated in P. fluorescens cultures; however, the results of the autoxidation studies suggested that a large amount of pigment c ould derive from the simple autoxidation of the chlorocatechols accumu lated in the CP30 culture during the 3-chlorobenzoate degradation. The polymerization of chlorocatechols should reduce the toxicity of the c ulture and generally resulted in a large production of a water-insolub le (i.e. a easily removable) pigment with the release a large amount o f chloride ions. Both 3-chlorobenzoate degradation and pigment product ion were stimulated and inhibited in the same way by high and low pH v alues, respectively, in CP30 cultures; the culture conditions which pe rmitted an extensive 3-chlorobenzoate degradation with the lowest pigm ent production were not identified. However, on the basis of the detox ification property of the pigment production process, high pH and diss olved oxygen concentrations appears to be the most suitable culture co nditions for an enhanced detoxicant treatment of 3-clorobenzoate-conta minated waste water.