THE EFFECT OF NUTRIENT LIMITATION ON STYRENE METABOLISM IN PSEUDOMONAS-PUTIDA CA-3

Styrene degradation in Pseudomonas putida CA-3 has previously been sho wn to be subject to catabolite repression in batch culture. We report here on the catabolite-repressing effects of succinate and glutamate a nd the effects of a limiting inorganic-nutrient concentration on the s tyrene degradation pathway of P. putida CA-3 in a chemostat culture at low growth rates (0.05 h(-1)). Oxidation of styrene and the presence of styrene oxide isomerase and phenylacetaldehyde dehydrogenase activi ties were used as a measure of the expression of the styrene degradati on pathway. Both glutamate and succinate failed to repress the styrene degradation ability under growth conditions of carbon and energy limi tation. Lower levels of enzyme activities of the styrene degradation p athway were seen in cells grown on styrene or phenylacetic acid (PAA) under conditions of both ammonia and sulfate limitation than were seen under carbon and energy limitation. Cells grown on PAA under continuo us culture oxidize styrene and styrene oxide and possess styrene oxide isomerase and NAD(+)-dependent phenylacetaldehyde dehydrogenase activ ities. Catabolite repression of styrene metabolism was observed in cel ls grown on styrene or PAA in the presence of growth-saturating (nonli miting) concentrations of succinate or glutamate under sulfate limitat ion.