Biodegradation of Diesel Oil Using Acinetobacter Ncimb 110507 and Pseudomonas Putida Nas 1(4)

Characterization and screening of stock cultures for application in diesel degradation was undertaken. Two isolates from the stock cultures from University of Wolverhampton Culture Collection (UWCC) were selected based on their positive growth on streak plates containing hydrocarbon media and were isolated into pure culture. The isolates were characterized and their identities were reconfirmed by carrying out a different biochemical test. All the tests and the biochemical characteristics agreed with the expected results of each organism. The isolates consisted of two Gram-negative rods P. putida NAS 1(4), and Acinetobacter (NCIMB 110507). The results showed that Acinetobacter and P. putida grew better in 0.5% and 1.0% concentration of the compounds. Optimum growth was observed at the temperature of 20⁰C to 37⁰C and no growth was observed at 40⁰C. Also, as the concentration increased from 0.5% to 2.0%, the rate of growth on these compounds reduces. Pseudomonas putida NAS 1(4) had a better growth at 2.0 %v/v concentration of hexadecane, sodium benzoate, and diesel oil as compared to Acinetobacter. The minimum inhibitory concentration (MIC) for P. putida was more than 50% for all the compounds and the MIC for Acinetobacter NCIMB 110507 was 12.50 % for Sodium Benzoate and more than 50% for hexadecane and diesel oil. Acinetobacter had better growth at 20⁰C having the highest optical density of 1.77 and percentage TPH degradation of 85.2% after 144hrs of incubation, degradation was higher for Acinetobacter than for P. putida NAS 1(4). Acinetobacter NCIMB 110507 degraded 100% most of the light fraction of diesel alkane at 20⁰C (C8, C9, C10, C11, C14, C20, C22) and 64.31% for C19 while at 40⁰C, the range of degradation was 1.18 to 100% as demonstrated by GC-FID chromatogram analysis. For P. putida NAS 1(4), the range of degradation for C8-C22 at 20⁰C was 0 to 35.0% while at 40⁰C it was 0 to 21.0%.