Abstract:

A bacterial strain OCNB-1 was isolated from the activated sludge in the wastewater treatment plant of a chemical factory, with o-chloronitrobenzene as the sole carbon, nitrogen and energy sources. The strain was then identified as Pseudomonas putida by the automatic biometrical system WSVTK-R07.02 and the 16S rDNA sequence analysis. Afterwards, the strain was applied to the degradation of 1.07 mmol/L o-chloronitrobenzene at a rotation speed of 120r/rain, a pH value of 8.0 and a temperature of 32℃ , finding that about 80% of o-chloronitrobenzene is degraded by the strain after 42 h. The results of plasmid detection indicate that there exists a plasmid strip in OCNB-1 strain, the plasmid size of which is proved to be about 32kbp according to the single cutting results by using 7 kinds of restriction enzymes. The results of antibiotic resistance reveal that the resistances of the strain to erythromycin, ampicillin and benzylpenicillin sodium have nothing to do with the plasmid, while those to rifampicin and chloramphenicol are related to the plasmid. Moreover, as the obtained plasmid can be transferred to Pseudomonas. stutzeri through bacterial conjugation and the conjugant can grow by using o-chloronitrobenzene as the sole carbon, nitrogen and energy sources, it is concluded that the plasmid carries the gene for o-chloronitrobenzene degradation.

Key words: o-chloronitrobenzene, degradation, Pseudomonas putida, identification, plasmid