Assessment of the Plasmid Mediated Biodegradation of Crude Oil under Optimal Growth Conditions

Abstract

The present study was undertaken to assess the role of plasmid-mediated biodegradation of crude oil under optimal growth conditions. Enrichment techniques, turbidometric test, antimicrobial susceptibility testing, plasmid curing test and optimal biodegradation conditions were carried out using standard procedures. The results indicated that 22 of the isolates were observed to have high pollutant degrading potentials (A600nm > 0.3) due to their crude oil utilization ability. Isolates designated as C₁, D₁, L₂ and J₃ showed various degrees of growth after curing of their plasmids whereas isolates G₂, H₄, K₄ and I₆ were unable to grow after plasmid removal. It was observed that 4 plasmid-borne cells resisted the antibiotics tested after pre-cured examination but these isolates were 95% sensitive to the same antibiotics after post cured test. The results further indicated that isolates which were able to degrade crude oil belonged to genera Bacillus, Pseudomonas sp., Ochrobacterium sp. and Enterobacter sp. Moreso, neutral pH, 35 °C temperature and 3 % crude oil concentration were found to be optimal conditions for crude oil bioaugmentation study. Thus, the study indicated that the crude oil-utilizing bacteria which are part of the soil ecosystem could be exploited for natural and terrestrial remediation of crude oil-polluted environments.