High Molecular Weight Polycyclic Aromatic Hydrocarbons Biodegradation by Bacteria Isolated from Contaminated Soils in Nigeria

Abstract

Bacteria isolated from various contaminated soils in Nigeria were investigated for their potential to utilize and biodegrade high molecular weight polycyclic aromatic hydrocarbons which include chrysene, fluoranthene and pyrene. Biochemical and morphological studies identified the isolates as Sphingomonas sp., Pseudomonas sp. and Pseudomonas putida. Biodegradation studies showed that Sphingomonas sp., Pseudomonas sp. and P. putida degraded 100 mg L-1 chrysene to 30.5±0.3, 40.6±0.7 and 17.2±0.2 mg L-1, respectively after 8 days of incubation. Similarly, fluoranthene was degraded to 2.0±0.1, 2.0±0.4 and 0.12±0.1 mg L-1 while pyrene to 0.16±0.2, 6.5±0.3 and 6.6±0.4 mg L-1 correspondingly. Consortium of the isolates degraded 100 mg L-1 chrysene, fluoranthene and pyrene, respectively to 21.3±0.9, 2.2±0.8 and 10.6±0.8 mg L-1. In the presence of phenanthrene as co-substrate, chrysene, fluoranthene and pyrene were, respectively degraded by consortium to 12.4±0.5, 0.2±0.3 and 0.7±0.2 mg L-1 while phenanthrene was undetectable. This study showed that there was delayed degradation of chrysene and fluoranthene in the presence of phenanthrene, this may account for the persistence of these compounds in polycyclic aromatic hydrocarbons polluted sites. This is the first report on the potential of these isolates simultaneous utilization and biodegradation of chrysene, fluoranthene and pyrene when used as sole carbon and energy source.