Isolation Of Phenanthrene Degrading Bacteria From Oil-contaminated Soil And Their Effects On Phenanthrene Degradation

Polycyclic aromatic hydrocarbons (PAHs), which consist of two or more fused aromatic rings, are widespread in the environment and persist over long periods of time. The decontamination of PAH-polluted environment is of importance because some PAHs are toxic, mutagenic, and carcinogenic and therefore are health hazards. In this paper, isolation of polycyclic aromatic hydrocarbon-degrading bacteria was conducted in plate medium by selective enrichment culture. Two isolates of FC31 and FC32 were obtained by the method of sublimation from petroleum-contaminated soil;FC31 was identified as Bacillus firmus and FC32 as Achromobacter xylosoxidans subsp. denitrificans based on analysis of 16S rDNA sequence and Biolog-GN profile;Both strains grew well on sole carbon of phenanthrene and degrade it efficiently and both strains showed catechol dioxygenase activity and higher phenanthrene-degrading capacities in broth assay;The amount of phenanthrene degradation was correlated with the OD value. The results indicated that the ability of phenanthrene-degrading increase greatly when they were used as a mixture;With the method of plasmid elination,it was proved the genes encoding for degradation of phenanthrene locate on a plasmid;Study showed that different nutritional elements had significant effects on phenanthrene-degrading rates and phenanthrene uptake of crops in soil, but different organic amendments had insignificant effects on rice biomass and the emumeration of phenanthrene-degrading bacteria.