Degradation of chlorotoluenes by Comamonas testosterone KT5

Abstract

The isolated Comamonas testosterone KT5 utilized a broad range of toluene and chlorotoluenes, including 2-chlorotoluene, 3-chlorotoluene (3CT), 4-chlorotoluene, 2,3-dichlorotoluene, 2,4-dichlorotoluene, 2,6-dichlorotoluene and 3,4-dichlorotoluene (34DCT) as sources of carbon and energy. The strain was characterized its dissipation capability toward these compounds in both liquid culture and contaminated soil. In liquid cultures, KT5 utilized more than 90% of toluene, 3CT and 34DCT within 60 h at the initial concentration of 2 mM. Moreover, the strain showed a mineralization capacity of mixtures of toluene and chlorinated toluenes. Inoculation with the toluenes-degrading bacterial strain significantly enhanced degradation rates in soil. The dissipation rates of toluene, 3CT and 34DCT in non-sterile soil inoculated with bacteria were 97.8, 93.5 and 68.9% after 30 days, respectively. The biodegradation of toluene and chlorosubstituted toluenes in KT5 was occurred through the upper pathway to form benzoates and then ring fission via ortho-cleavage pathway. In addition, C. testosterone KT5 showed the mineralization capacities of benzoate and chlorinated benzoates with the rates comparably higher than the rates of toluenes. The multiple and efficient toluene degradation properties make this isolate a good candidate for bioremediation of environments contaminated with chlorosubstituted toluenes and benzoates.