Biodegradation of mixed polycyclic aromatic hydrocarbons by Pseudomonas sp. isolated from estuarine sediment

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are released into the environment via several natural and anthropogenic sources leading to long-term consequences that severely affect the environment, ecosystem, human and animal health. In this study, the extent of PAH pollution was measured at two estuarine locations of the major rivers of Goa, Zuari and Mandovi. Out of the 16 PAHs marked as carcinogenic, 13 PAHs were detected from the sediment samples collected. Bacterial strains were isolated from these PAH-contaminated sediments using conventional plating method. Six of these selected bacterial isolates were checked for their efficacy to degrade both low (phenanthrene) and high molecular weight (fluoranthene and pyrene) hydrocarbons. Amongst them, two bacterial isolates exhibited over 80% degradation of phenanthrene. Isolate NIOSV7 (Pseudomonas pachastrellae) could degrade 83.33% phenanthrene, 40.22% fluoranthene and 45.28% pyrene, while isolate NIOSV8, identified as Pseudomonas oleovorans, showed 85.09% phenanthrene, 70.61% fluoranthene and 67.18% of pyrene degradation in 120 h, at 100 ppm initial concentration of phenanthrene and 75 ppm of fluoranthane and pyrene. Though many Pseudomonas sp. are documented for PAH degradation, this is the first report showing PAH-degradation by Pseudomonas oleovorans strain. This study also shows that the bacteria isolated from estuarine sediments contaminated with PAH have good potential to degrade low and high molecular weight PAHs. These toxic pollutants can be bio-transformed into nontoxic metabolites with the help of microorganisms isolated from the same habitat.