Effect of cosubstrates on the dechlorination of selected chlorophenolic compounds by Rhodococcus erythropolis 1CP

Abstract

Effects of aromatic and nonaromatic cosubstrates on the rate of 2,4-dichlorophenol degradation by R. erythropolis 1CP were studied under growth and nongrowth conditions. Glucose and maltose were found to accelerate 2,4-dichlorophenol (initial conc. 50 mg/l) dechlorination from 11 days to 24 and 20 h, respectively. The stimulating effect was observed within the range of glucose concentration of 0.5-2.0 g/l in the medium. Ascorbic acid at a concentration of 10-70 mg/l as a nongrowth substrate also increased the decomposition of 2,4-dichlorophenol, though at a lower degree than glucose. Experiments with washed cells showed the limiting stage of chlorophenol degradation by R. erythropolis 1CP to be, possibly, aromatic ring dechlorination after its hydroxylation. As an additional source of electrons, glucose introduced into suspensions of washed cells grown on 3-hydroxybenzoate made it possible to eliminate the bottleneck in 2,4-dichlorophenol metabolism by significantly accelerating dechlorination of 3,5-dichlorocatechol. Based on the experimental and literature data, the enzyme systems involved in 2,4-dichlorophenol degradation by the culture R. erythropolis 1CP are assumed to be nonspecific.