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.