[Isolation and identification of a pyrene-degrading bacterial strain from contaminated soil].

Objective: The aim of this study was to isolate high-molecular-weight polycyclic aromatic hydrocarbons (HMW-PAHs) degrading bacterial strains, and to study their degradation potential.

Methods: We used sublimation method to enrich and isolate the degrading bacteria from coking plant samples. Morphological properties, the sequence homology of 16S rRNA and gyrb genes were used to identify the isolated strains. GC-MS was used to analyze the degradation potential against some HMW-PAHs.

Results: An HMW-PAHs degrading bacterium,HBS1, was obtained. HBS1 could use several HMW-PAHs such as pyrene, benzoanthracene, benzopyrene, chyrsene, indeno[ 1,2,3-cd] pyrene, benzo[g,h,i]perylene and fluoranthene as sole carbon source for growth. HBS1 was identified as Gordonia sp., based on the high sequence similarities (more than 99%) of both 16S rRNA gene and gyrb gene to those of Gordonia amicalis. When the initial concentration of pyrene was 50 mg/L, HBS1 could consume 97% of the pyrene in 17 days. One fragment of the dioxygenase gene was obtained by PCR with size about 300 bp, which was closest to the counterpart from Mycobacterium sp. with 93.8% similarity.

Conclusion: We isolated a strain HBS1 from seriously PAHs-polluted soils and identified as a Gordonia sp. The isolate had the degradation potential of high-molecular weight polycyclic aromatic hydrocarbons.