Resumen de The aerobic dechlorination activities of two bacterial species isolated from a refuse dumpsite in Nigeria
Ademola O. Olaniran, Anthony I. Okoh, Stella Ajisebutu, Peter N. Golyshin, Gbolahan O. Babalola
Two bacterial species isolated using enrichment culture techniquesfrom the topsoil of a main refuse dumpsite in Nigeria were assessed for their dehalogenation potentials. The bacterial isolates were identified asbelo nging to the Bacillus and Pseudomonas genera. Axenic culturesof the isolates utilized monochloroacetic acid (MCA), trichloroacetic acid (TCA), trichloromethane (CHCl3) and tetrachloromethane (CCl4) as the sole source of carbon for growth up to a final substrate concentration of 0.1% (w/v). The mean generation timesof the isolatesin all the growth media ranged significantly (P < 0.05) from 2.41 to 10.04 h and were generally higher than that observed in glucose medium (1.46—1.51 h). The numbers of the chloride atoms in the different organochlorides were negatively correlated with the ability of the organisms to degrade the compounds. Dehalogenase specific activities of the cell-mediated culturesranged from 0.1 to 0.96 μg ml-1 chloride release (mg protein)-1 h-1 and were significantly (P < 0.05) higher than that of the cell-free extract [0.09—0.8 μg ml-1 chloride release (mg protein)-1 h-1]. The optimal pH of the dehalogenase activity was found to be 8.0, and the optimal temperature was between 30 and 35°C.
