[Population shift and degrading characteristics of a pyrene-degrading bacterial consortium during incubation process]

The work aimed to obtain pyrene-degrading bacterial consortium and use it for bioremediation of polycyclic aromatic hydrocarbons-contaminated soil.

We enriched and incubated a bacterial consortium utilizing pyrene as the sole carbon source from the contaminated soil of Beijing Coking Chemical Plant. We analyzed the degrading ability and growth of the consortium by high performance liquid chromatography (HPLC) and spectrophotometer. We investigated the degradation activities of the consortium after several times transfer and freeze-drying deposit. We also investigated the shift of bacterial consortium composition after several times transfer by combining of culture-dependent and culture-independent methods. We constructed and analyzed the 16S rRNA gene clone libraries at different transfer times (3 times PYR-3, 6 times PYR-6 and 9 times PYR-9) for monitoring the bacterial population changes.

The degradation rate of pyrene, phenanthrene and fluoranthene reached 89%, 86% and 49% respectively after incubation of the consortium for 12 days. The degradation activities of the consortium were stable after several times transfer and freeze-drying deposit. We isolated nine strains from the consortium, affiliated to genus of Achromobacter, Bacillus, Arthrobacter, Exiguobacterium and Parapedobacter. Phylogenetic analyses showed that Proteobacteria were the main group at contaminated soil sample (100%) and bacterial consortium incubated in pyrene (PYR-3, 83%). Bacterial community structure was shifted and biodiversity was increased during the transfer process, the proportions of gamma-Proteobacteria was decreased from 77% (PYR-3) to 33% (PYR-6) and 18% (PYR-9), while beta-Proteobacteria increased from 13% (PYR-3) to 36% (PYR-6) and 55% (PYR-9).

The bacterial consortium could utilize pyrene as sole carbon and energy source for growth and the degradation ability for pyrene was stable.