Isolation and Identification of Hydrocarbon-Degrading Bacteria from Diesel-Contaminated Soils

Aim: To Isolate, screen and identify bacterial species with hydrocarbon biodegradative potentials from diesel-polluted soils using redox indicator (2% v/v of 2,6 – dichlorophenol indophenols- DCPIP) and Turbidity measurements. Place and Duration of Study: Microbiology laboratory in the Department of Environmental Management and Toxicology, Federal University of Petroleum Resources, Effurun, between 2022 and 2024. Methodology: Soil samples from diesel-contaminated site were collected from diesel mechanic workshop, analysed using the spread plate isolation technique on Bushnell Haas mineral salt agar selective medium, were screened for Bacterial species with hydrocarbon degradative potential using the redox indicator (2% v/v of 2,6 – dichlorophenol indophenols- DCPIP) and Turbidity measurement. Selected Bacterial isolates were used for the hydrocarbon degradation studies, were characterized based on biochemical tests and identified with the aid of the Biolog database and 16S rRNA gene sequencing techniques. Results: Eight diesel degrading Bacteria species were identified, belonging to the following genera; Acinetobacter, Klebsiella, and Pseudomonas. Among these, the four most potent degraders were identified as Acinetobacter rudis (M2712942.1), Acinetobacter bereziniae (MT111619.1), Pseudomonas koreensis (MW794239.1), and Klebsiella aerogenes (CP070520.1) and the % diesel reduction achieved in 15 days were; 70%, 48%, 47% and 45%, while the % Turbidity increase were 84%, 79%, 78% and 76% respectively. Consequently, the partial 16S rRNA gene sequences revealed the two most potent diesel degrading bacterial strains were Acinetobacter rudis and Acinetobacter bereziniae with 70% and and 48% respectively. Conclusion: These findings demonstrate the potential of indigenous bacteria for effective bioremediation of petroleum-contaminated environments. The study provides critical insights into sustainable solutions for mitigating hydrocarbon pollution, contributing to advancements in environmental microbiology and ecosystem restoration.