Improvement of Hydrocarbon Degrading Bacteria Isolated from Automobile Mechanic Workshop Contaminated Soil Using Rock Phosphate

Abstract

Indiscriminate discharge of used petroleum products or spillage is a source of pollution to our environment hence, the need for a concerted effort in studying the possibility of using oil degrading bacteria for remediation. This study was aimed at investigating the effect of rock phosphate supplementation on bacteria degradation of crude oil contaminated medium. Bacteria species were isolated from contaminated soil in mechanic workshops and screened for their hydrocarbon degradation potentials using standard microbiological procedures. The screened isolates and their consortium were used for the degradation of crude oil using minimal salt medium supplemented with rock phosphate for 20 d. Parameters investigated were pH, fungal load, phosphate solubilization, available phosphorus and hydrocarbon content. The identified bacterial isolates were Pseudomonas fluorescens, Corynebacterium glutamicum, Micrococcus luteus, Escherichia coli and Bacillus subtilis. The screened isolates were Pseudomonas fluorescens and Bacillus subtilis. The degradation result showed that the highest bacterial load and available phosphorus content were from rock phosphate crude oil Mineral Salt Medium (RCMSM) and consortium with values 16.69±0.40 cfu/mL and 14.97± 0.03 mg/L respectively on day 16. The least values 6.00±0.19 cfu/mL and 0.71±0.06 mg/L were from crude oil Mineral Salt Medium (CMSM) P. fluorescens and CMSM consortium respectively. Statistically, data from RCMSM and consortium were significantly different from other media and inoculum used (p< 0.05). The results suggested that the consortium of the isolates could be used in remediating crude oil contaminated soils.