Biodegradation of pentachloronitrobenzene by Arthrobacter nicotianae DH19.

UNLABELLED: A pentachloronitrobenzene (PCNB)-degrading bacterial strain was identified as Arthrobacter nicotianae based on morphological, physiological and biochemical tests, and 16S rRNA gene sequences analysis. The strain could grow on mineral salt medium (MSM) containing PCNB as the sole carbon source. Under optimal conditions (pH 6·85, 30°C and inoculum biomass amount of 1·45 g l(-1) ), more than 90% residues of PCNB were degraded by strain DH19 within 7 days. Strain DH19 could efficiently degrade dichlorodiphenyl trichloroethane, hexachlorocyclohexane, cypermethrin and cyhalothrin. Metabolites from PCNB degradation were identified by using gas chromatography (GC) coupled with triple quadrupole mass spectrometry. A possible degradation pathway for PCNB was deduced. This is the first report of PCNB-degrading strain DH19 isolated from the rhizospheric soil. Therefore, strain DH19 could potentially be employed in bioremediation of PCNB. SIGNIFICANCE AND IMPACT OF THE STUDY: The degradation of pentachloronitrobenzene (PCNB) by an individual bacterial strain is being reported for the first time. The efficient PCNB-degrading strain DH19 was isolated from ginseng rhizosphere soil and identified as Arthrobacter nicotianae. The strain could utilize PCNB as the sole carbon source for growth and degradation. In addition, strain DH19 could efficiently degrade dichlorodiphenyl trichloroethane, hexachlorocyclohexane, cypermethrin and cyhalothrin. Five metabolites from PCNB degradation were identified, and a possible degradation pathway was deduced. The results suggest that A. nicotianae DH19 has great potential for the bioremediation of PCNB-contaminated environments.