ASSESSMENT AND CHARACTERIZATION OF INDIGENOUS BACTERIAL SPECIES FROM HYDROCARBON-CONTAMINATED SOILS IN MAIDUGURI, BORNO STATE, NIGERIA.

ABSTRACT Petroleum hydrocarbon contamination from the indiscriminate discharge of used engine oil poses a significant environmental risk in urban areas of Borno State, Nigeria. This study was conducted to assess the intrinsic bioremediation potential of microbial populations across three mechanic workshop sites in Maiduguri: 777 Housing Estate, Federal Low-Cost (FLC), and Ngomari Old Airport (NOA) mechanic sites. Standard microbiological techniques, including serial dilution, plating on selective media (Bushnell-Haas Agar), and definitive biochemical characterization, were employed. The results showed a highly enriched microbial community, with Total Heterotrophic Bacterial Counts (THBC) consistently exceeding CFU/g in all samples. The percentage frequency of Hydrocarbon-Degrading Bacteria (HDB) was exceptionally high, reaching 112.97% at the FLC site, confirming a profound endemic adaptation to hydrocarbon stress. A total of ten (10) isolates were purified and identified, belonging to seven distinct bacterial genera, including the globally recognized, potent hydrocarbon degraders: Pseudomonas (P. aeruginosa, P. fluorescens), Bacillus (B. licheniformis, B. cereus), Acinetobacter, Flavobacterium, and Nocardia. The isolates uniformly tested Catalase and Citrate positive, demonstrating high metabolic versatility and resilience against oxidative stress associated with oil degradation. The study concludes that the hydrocarbon-contaminated soils in Maiduguri possess a strong intrinsic bioremediation potential due to this diverse and metabolically fit indigenous bacterial consortium. These findings provide a critical foundation for developing cost-effective, locally-tailored bioaugmentation strategies for petroleum cleanup in the region. Keywords: Bioremediation, Hydrocarbon Contamination, Pseudomonas, Bacillus, Indigenous Microflora, Used Engine Oil, Maiduguri.