Biodegradation of pyrene by a newly isolated Proteus vulgaris

Abstract

This work was aimed at identifying a new strain which can degrade pyrene effectively and quickly. Strain 4Bi was identified as Proteus vulgaris based on several morphological, biochemical characters and 16S rRNA phylogeny by using conventional methods, API and 16S rRNA gene sequence analysis. 16S rRNA gene sequence of the bacterium has been deposited in GenBank database under the accession number FJ799903. Carbon free mineral medium (CFMM plus pyrene) used for P. vulgaris 4Bi was excessively sufficient for positive improvement of bacterial growth and pyrene removal. The growth rates and pyrene degradation rates were increased depending on the time in CFMM. At a biodegradation rate with an initial pyrene concentration of 0.5 mg /ml, 71.5% of pyrene was degraded in 7 days. Pyrene-degradation metabolites were detected by HPLC and TLC analyses. Pyrene is a highly stable compound containing four fused aromatic rings and is one of the representative higher molecular weight-polycyclic aromatic hydrocarbons that are recalcitrant to biodegradation. Whereas, our bacterium could degrad pyrene effectively and quickly. With our study, the strain of P. vulgaris was firstly reported among pyrene-degrading bacteria. The ability of this strain is very useful for the remediation of pyrene one of PAH pollutants. Also, degradation metabolites detected in the study are not toxic or nonpersistent compounds in nature. These results indicated that this novel pyrene-degrading strain has a strong potential for further bioremediation processes without undesirable metabolites. Key words: Polycyclic aromatic hydrocarbons, pyrene, Proteus vulgaris,identification, biodegradation, metabolites.