Aerobic dehalogenation potentials of four bacterial species isolated from soil and sewage sludge

Four bacterial species each were isolated from soil and a sewage oxidation pond using enrichment culture technique, and the bacterial isolates were identified to belong to the two genera Bacillus and Corynebacterium. The axenic cultures of the isolates utilized monochloroacetic acid (MCA), trichloroacetic acid (TCA), CHCl3 and CCl4 for growth up to 1 g substrate l−1 (w/v) and growths were enhanced in the mixed cultures of the isolates. The specific growth rate constants in the media ranged from 0.144 to 0.475. This is lower than the comparatively high values observed for the glucose medium, which varied significantly (P<0.05) between 0.699 and 0.792 h−1. Serial adaptation of the individual isolates in the organochloride media significantly (P<0.05) affected the bacteria growth yields. The dehalogenase specific activity observed in the cell-free extracts of the mixed cultures of the isolates was significantly higher (P<0.05) than those of their respective monocultures. Optimal pH of the dehalogenase activity was between 7.6 and 8.0, while temperature optima were between 30°C and 35°C.