BIODEGRADATION OF DICHLOROACETIC ACID BY ENTRAPPED AND ADSORPTIVE IMMOBILIZED XANTHOBACTER-AUTOTROPHICUS GJ10

The degradation of dichloroacetic acid (DCA) by free, Ca-alginate entr apped and adsorptive immobilized cells of Xanthobacter autotrophicus G J10 has been studied in various experimental systems. Entrapped cells tolerated increasing concentrations of DCA better than free cells. Fre e and adsorptive immobilized cells degraded DCA most effectively at ma xiMUM O2 supply, 34-degrees-C and an initial pH value of 8.0. The degr adation of high DCA concentrations led to a decrease in the pH value a nd to a stagnation of mineralization, particularly with free or entrap ped cells. Due to the stabilization of pH, the supplementation of acet ate or succinate resulted in a complete degradation of higher DCA conc entrations. Higher degradation rates than in shake cultures were achie ved in air-bubble and packed-bed fermentors. DCA was mineralized faste r by free or entrapped X. autotrophicus GJ10 than by adsorptive immobi lized cells, which, however, were able to remove higher DCA concentrat ions. The results of the recent investigations with immobilized X. aut otrophicus GJ10 are an important prerequisite for the application of t his bacterium in waste treatment systems.