[Isolation and identification of a highly efficient pyrene-degrading Mycobacterium sp. strain N12].

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 x L(-1) of pyrene by the strain N12 was 94.4% within 7 days and 100% after 14 days, and that of 600 mg x 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.

[Identification and degradation capability of three pyrene-degrading Gordonia sp. strains].

Three pyrene-degrading bacterial strains named D44, D82S and D82Q were isolated from PAHs-contaminated soil in Shenfu Irrigation Area of Shenyang, Northeast China. The strains were identified as Gordonia sp., based on the morphological observation, physiological and biochemical identification, and phylogenetical analysis of 16S rDNA sequences. For all the three stains, their optimal pH was 7, and their growth was obviously inhibited when the pH was lower than 5 or higher than 9. The three strains were capable of utilizing pyrene, benzo[a] pyrene, anthracene, naphthalene, phenanthrene, and fluoranthene as the sole source of carbon and energy. After seven days incubation, the three strains could degrade more than 65% of pyrene with an initial concentration 100 mg x L(-1), and the D44, D82S, and D82Q could degrade 79.6%, 91.3%, and 62.8% of benzo[a] pyrene with an initial concentration 50 mg x L(-1), respectively. PCR amplification indicated that the strains D82Q and D82S possessed alkane monooxygenase gene alkB.