Degradation of crude oil by the microbial populations of Lagos and Ologe lagoon waters

Abstract

Introduction: hydrocarbon contamination of surface waters as a result of anthropogenic activity poses threat to ecosystems and counter their beneficial uses. Some indigenous microbial communities have the potential to purify such waters unaided. Aims: To show the biodegradative potential of microbial communities in Lagos and Ologe Lagoons during minimal pollution with crude oil. Materials and Methods: The total heterotrophic bacteria and hydrocarbon utilising bacterial and fungal populations were estimated from Lagos and Ologe lagoon water samples contaminated with 1% crude oil over 42-day incubation period by plate count and vapour-phase transfer techniques. Residual hydrocarbons were determined by Gas chromatography. Results: The predominant bacterial genera identified from the lagoons include Enterobacter, Klebsiella and Proteus, while Escherichia, and Morganella. Aspergillus and Mucor were the predominant fungal genera in both waters. The hydrocarbon degradation rate in the Lagos Island microcosm was 65.391±0.370 mg/l/d, degradation rate constant 0.05±0.01 /d, half-life 9.559±0.093 /d and percentage degradation of 95.315 ± 0.134. Corresponding values in the Ologe water were 61.190± 8.542 mg/l/d, 8.725 ±0.389 /d, 0.055±0.003/d and 96.345±0.488 respectively. There was almost complete disappearance of the various fractions of the oil in the two samples. The microbial communities from both lagoons effectively utilised majority of the hydrocarbon fractions after 42 days where 66.890±1.075 and 100±000 were recorded for benzene, toluene had 100±000 percent degradation, anthracene 96.755±0.119 and 99.726±0.026, and pristane had 91.674±0.222 and 99.943±0.015 while phytane had 96.44±0.058 and 99.670±0.104 respectively. Conclusion: Efficient biodegradation of moderate contamination crude oil could be achieved by indigenous microbial flora present in Lagos and Ologe lagoon waters.