An approach to develop bioremediation by isolation and characterization of microorganisms from soil contaminated with used lubricating oil

Soil contamination with used lubricating oil (ULO) is an emerging environmental threat in many parts of the world. Bioremediation is a novel, cost effective green technological approach with a great potential to remediate soil contaminated with ULO. Therefore, the present study aimed to isolate, and characterize microorganism/s with the capability to degrade ULO from the ULO contaminated soil as an attempt to develop a bioremediation technique. Two novel strains, RUH-K01 and RUH-F07 were isolated from ULO contaminated soil as efficient ULO degraders. They were identified as P. aeruginosa RUH-K01 and A. fumigatus RUH-F07 with respect to their morphological characteristics and analysis of 16S rRNA gene sequences. Microcosm experiments revealed the contamination level dependent slight reduction in ULO degradation in both strains when the ULO contamination level increased (1-4% w/w). The potential to produced biosurfactant and other species specific factors might have caused for the resulted more efficient biodegradation of ULO by P. aeruginosa RUH-K01 compared to A. fumigatus RUH-F07. The resulted significant (P<0.05) negative correlation between the residual total petroleum hydrocarbon (TPH) content and total microbial activity (TMA) of both strains confirmed the applicability of FDA assay as an alternative method to characterize ULO degradation efficiency of microorganisms. Therefore, the overall results indicate that the greater potential of P. aeruginosa RUH-K01 and A. fumigatus RUH-F07 to be used in remediation of ULO contaminated soil. The findings of the present study will be vitally important for establishing a bioremediation technique mediated by microorganisms.