ISOLATION AND IDENTIFICATION OF ZINC RESISTANT BACTERIA FROM ENGINE OIL CONTAMINATED SOIL

Soil contamination from prolonged disposal of used engine oil remains a pressing environmental concern, especially around auto-mechanic workshops in developing regions. Such pollution introduces heavy metals, including zinc, into the soil, which disrupts ecological balance and poses health risks. This study was undertaken to isolate, characterize, and evaluate zinc-tolerant bacteria from engine-oil contaminated soils collected around Sa’adu Zungur University, Bauchi State, Nigeria. Soil samples were aseptically collected, serially diluted, and cultured using standard microbiological techniques. Pure isolates were obtained and subjected to morphological, Gram staining, and biochemical characterization. Results revealed a Bacillus species, identified as Gram-positive, rod-shaped, catalase and coagulase positive but indole-, Voges Proskauer-, and urease-negative. Growth studies demonstrated that the isolate exhibited optimal proliferation at 25 °C, moderate growth at 35 °C, and reduced growth at 45 °C, reflecting its mesophilic nature. When exposed to varying zinc concentrations, the bacterium showed strong tolerance at moderate levels (100-200 µL) but reduced growth at higher concentrations (300-500 µL). These findings highlight the resilience of Bacillus spp. in zinc-polluted environments and suggest its potential application in bioremediation strategies for contaminated soils. This study underscores the importance of harnessing native microbial resources for sustainable environmental management.