Exploration of the catabolic plasmid genes profile of crude oil degrading bacteria isolated from aged oil contaminated soils of Anambra State

Abstract

This study was undertaken to explore the catabolic plasmid genes profile and molecular identification of crude oil degrading bacteria isolated from aged oil contaminated soils of Anambra State. Enrichment technique, turbidometric test, plasmid profiling and curing tests, biodegradation capability testing as well asmolecular identification method were carried out using standard procedures.A total of sixty (60) bacterial isolates were encountered in the four different soil samples. Of the total bacterial isolates, 22 strains demonstrated high crude oil degrading potentials (A600nm > 0.3). The plasmid DNA was present in 8 out of the 22 bacterial strains such that bacteria strains G2, H4, and K4 had one plasmid each with molecular weight of 9416 base pairs while bacteria strains C3, D1, J3 and L2 had two plasmids each with molecular weight of 2111 base pairs. The bacterial strains C1 and J3 recorded the highest growths on the solid media after the plasmid removal. The isolates belong to various species which are Bacillus cereus C12 (100 % similarity), Pseudomonas aeruginosa KAVK01 (100% similarity), Bacillus licheniformis 126 (96 % similarity), Ochrobacteriumintermedium E85b (97% similarity), Bacillus subtillis SDDlas (100 % similarity), Bacillus subtillis LK4.5 (97 % similarity),Enterobacter cloacae GEBRI III (97 % similarity) and Bacillus cereus So24 (100 % similarity). Therefore, plasmid-borne Pseudomonas aeruginosa and Ochrobacteriumintermediumare recommended for use in bioremediation because of their resilience to the crude oil contaminant and degradation capacities.