Biotechnological Prospects of Indigenous Oil‐Degrading Bacteria for Engine Oil Remediation and Environmental Restoration in Mekelle, Ethiopia

This study addressed environmental pollution from engine oil discharge in Mekelle's workshops by isolating and characterizing oil-degrading bacteria for bioremediation applications. Soil and water samples collected from 10 garage centers were analyzed for physicochemical properties, yielding six isolates: Pseudomonas aeruginosa, Bacillus cereus, Staphylococcus aureus, Acinetobacter baumannii, Bacillus pumilus, and Bacillus megaterium. Oil degradation assays on Bushnell-Haas agar with engine oil at 37°C for 14 days revealed that B. pumilus (98.9% ± 91.6%) and A. baumannii (98.7% ± 80%) were most effective in soil, while B. megaterium (96.9% ± 92.8%), B. cereus (96.7% ± 88.2%), and P. aeruginosa (96.5% ± 84.6%) excelled in water, with B. megaterium also showing high degradation in media (98.9% ± 88.8%). Biosurfactant production was strongest in P. aeruginosa, A. baumannii, and B. cereus; heavy metal tolerance was broad in S. aureus and A. baumannii; and salt tolerance was notable in P. aeruginosa, B. megaterium, B. cereus, and B. pumilus. Antibiotic susceptibility testing indicated that P. aeruginosa, A. baumannii, and B. megaterium could be safely applied in bioremediation, while resistance in B. cereus, S. aureus, and B. pumilus requires careful management. In conclusion, these isolates demonstrate strong potential as ecofriendly agents for oil spill remediation in Mekelle and similar environments.