Degradation Characteristics and Metabolic Pathway of a Pyrene-Degrading Pseudomonas aeruginosa Strain

Abstract

Polycyclic aromatic hydrocarbons (PAHs) pose a potential threat to ecosystems due to their mutagenic, carcinogenic, and teratogenic effects. Microbial degradation has been suggested as the best way to remove PAHs from contaminated environments. Screening of bacterial strains capable of efficiently degrading PAHs is the key to the bio-remediation technique. With the method of enrichment culture, the bacterial strain LX2, which can use pyrene as the sole carbon source, was isolated from sludge contaminated with PAHs. The strain was identified as Pseudomonas aeruginosa (Pseudomonas sp. LX2) according to the results of the analyses of its morphology, physiology, and phylogeny of its 16S rDNA sequence. The degradation rate of pyrene by Pseudomonas sp. LX2 was 32.1% after 21 days of cultivation at an initial pyrene concentration of 50 mg·L-1. Pyrene, 4,5-dihydro-, 2'-Hydroxypropiophenone, Phenol, and Protocatechuate were identified as the major metabolites by GC/MS analysis. Based on the identified metabolites, it was concluded that pyrene was degraded via two different routes by Pseudomonas aeruginosa, namely the 'naphthalene' and the 'phthalic acid' routes.