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अमूर्त

Biodegradation of Fresh and Used Engine Oils by Pseudomonas aeruginosa LP5

Oluwafemi S Obayori, Lateef B Salam and Oluwatoba S Ogunwumi

Pseudomonas aeruginosa strain LP5, a hydrocarbon degrader isolated from petroleum contaminated soil based on its ability to grow on pyrene, was used to degrade two different grades of fresh and used engine oil (SAE 40W and SAE 20W 50) in liquid cultures. The organism degraded more than 90 percent of all oil types within 21 days with values of 95%, 93%, 96% and 92% for fresh SAE 40W, used SAE 40W, fresh SAE 20W 50 and used SAE 20W 50 respectively. Similarly, growth rates were slightly higher in the fresh oils with values of 0.17, 0.13, 0.14 and 0.13 d-1 recorded respectively for fresh SAE 40W, used SAE 40W, fresh SAE 20W 50 and used SAE 20W 50. Significantly higher initial rates of degradation of 177.42 mg l-1d-1 and 207.14 mgl-1d-1 were recorded for fresh SAE 40 and SAE 20W 50 in the first 21 days compared to the values for the used oil counterparts, which were 73.23 mgl-1d-1 for SAE 40 and 74.37 mgl-1d-1 for SAE 20W 50. In the used oils, lower peaks that were not present at Day 0 reappeared on Day-21. All peaks greater than C20 also disappeared. In all cases, it was the medium fraction ranges of C14, C15, and C17 that remained with discernible peaks on Day 21, albeit at very low heights of less than 10% of Day 0 values. Thus whereas degradation rates differ on oil types and fresh oil appear more amenable to early degradation, the organism Pseudomonas aeruginosa LP5 showed remarkable potential for use in degradation of both fresh and used engine oils.