The discharge of used crankcase oil from vehicles is a major source of oil pollution in Buea. The
objectives of this study were to isolate and characterize bacteria capable of effectively degrading and
cleaning up waste engine oil in this locality and also to ascertain the influence of some environmental
factors on the rates of degradation of these isolates. Seventy-two soil samples collected from
lubricating oil dump sites (3 auto-mechanic workshops and 3 petrol filling stations, comprising
impacted soils) and uncontaminated plots (non-impacted soils) (controls) were analysed for oildegrading
and heterotrophic bacteria following standard microbiological and biochemical methods. The
ability of cultures to degrade lubricating oil was also tested individually and in mixed bacterial
consortium at different temperatures and nutrient concentrations. Results were analysed using the chisquared
test. P values of < 0.05 were considered significant. Heterotrophic bacterial counts were
significantly higher (P < 0.05) in non-impacted than in impacted soils. Conversely, the population of oil
degraders was significantly lower (P < 0.05) in non-impacted than in impacted soils. Oil degraders
isolated included Pseudomonas fluorescens, Bacillus mycoides and Serratia marcescens. Of the pure
isolates, Serratia marcescens degraded the highest amount of oil (36.2%). However, a mixed culture of
the isolates proved to be more effective, degrading 38.1% of oil within 20 days. All the isolates
exhibited highest degradation at 32°C; and degradation rates of Pseudomonas fluorescens and Bacillus
mycoides increased with increase in nutrient concentration. This study, the first of its kind in Buea,
revealed the presence of oil-degrading bacteria in soils as well as the physico-chemical requirements of
these bacteria for optimum degradation. This finding could be exploited in case of oil-spill clean-up
campaigns.