Biodegradation of Polycyclic Aromatic Hydrocarbon Mixtures by Rhodococcus Pyridinivorans FF2 and Pseudomonas Aeruginosa F4b Isolated from Sediments of Lagos Lagoon, Nigeria

Abstract

Polycyclic aromatic hydrocarbons (PAH) are widespread environmental pollutants that need urgent attention because of their toxicity. Development of microbial inoculants for PAH bioremediation is a potential avenue by which the environmental hazards posed by PAH can be addressed. The goal of the study was to determine if using PAH mixtures, rather than single PAH, as enrichment substrates would yield isolates that have superior PAH degradation abilities and/or are retrieve novel taxa from the PAH-contaminated sediments of Lagos Lagoon, Nigeria. The use of a quaternary mixture of PAH (pyrene, fluoranthene, fluorene, benz[a ]anthracene) was successful in yielding two isolates, Pseudomanas aeruginosa strain F4b and Rhodococcus pyridinivorans strain FF2 with capabilities to grow on multiple PAH, and thus potentially useful in bioremediation. In addition to the PAH degraded both isolates could grow on a wide range of other hydrocarbon substrates. The isolates of P. aeruginosa and R. pyridinivorans were identified as possessing PAH ringhydroxylating dioxygenases of the nahAC and narAa genotypes, respectively. The present study extends our knowledge of PAH biodegradation by P. aeruginosa and is the first report of PAH biodegradation by R. pyridinivorans. The capability of the R. pyridinivorans isolate to effectively degrade a highly toxic PAH, benz[a]anthracene, has particular importance for use in bioremediation.