Abstract: By using selective enrichment method, a highly efficient pyrene-degrading bacterium strain N12 was isolated from an oil-contaminated soil collected from Shenfu irrigation area of Shenyang. Based on the physiological and biochemical characteristics and the phylogenetic similarity of 16S rDNA gene sequence, the strain N12 was identified as Mycobacterium sp., which could utilize phenanthrene, acenaphthene, fluorine, and pyrene, but not anthracene, naphthalene, and benzo(a)pyrene as the sole carbon and energy source. However, when the strain N12 was cultured with pyrene and phenanthrene, 79.0% of benzo(a)pyrene could be co-metabolized within 9 days. The degradation rate of 100 mg·L^-1 of pyrene by the strain N12 was 94.4% within 7 days and 100% after 14 days, and that of 600 mg·L^-1 of pyrene was 56.1% within 7 days and 95.5% within 14 days. The addition of glucose promoted the degradation of pyrene. It was suggested that the strain N12 was an efficient PAHs-degrading bacterium, being a potential candidate for the bioremediation of PAHs-contaminated soils.

Key words: Mycobacterium, PAHs, pyrene, microbial degradation