BIODEGRADATION OF DICHLOROACETIC ACID BY FREELY SUSPENDED AND ADSORPTIVE IMMOBILIZED XANTHOBACTER-AUTOTROPHICUS GJ10 IN SOIL

Xanthobacter autotrophicus GJ10 was applied in a packed-bed fermentor to degrade dichloroacetic acid (DCA) in batch-, semicontinuous and con tinuous culture. Degradation has been studied with freely suspended an d adsorptive immobilized cells. To imitate natural soil systems, the f ermentor was filled with sand. Concentrations of up to 20 mM DCA were degraded completely. If higher initial concentrations were used, the d ecrease in pH value inhibited further growth and degradation. In conti nuous culture the fermentor was inoculated additionally with activated sludge. Over a period of 2 weeks the specialized strain could be reta ined and no decrease in metabolic activity was observed. A decrease in degradation of DCA was observed when succinate was added as a second substrate. The haloacid dehalogenase was found to be induced by DCA. N on-induced cells showed typical repression of catabolites and diauxic growth with succinate as co-substrate. The results demonstrate that X. autotrophicus GJ10 might be suitable for applications in biological w aste treatment systems.