Journal of Emerging Trends in Engineering and Applied Sciences: Research Areas

Article Title: A Study of the Abilities of Pseudomona Aeruginosa and Pseudomonas Fluorescens to Degrade Diesel Oil
by O.O. Olanipekun; A.O. Ogunbayo; and S.K. Layokun

Abstract:
Pseudomonas aeruginosa and Pseudomonas fluorescens are among the common bacteria found to mediate in the biodegradation of hydrocarbon, as well as in cleaning up environment contaminated with such. But little is known about their contributions, in term of their abilities in degrading diesel oil. Therefore, this study is with a view to establish and compare their bioremediating potentials on diesel oil. The pure and mixed cultures of Pseudomonas aeruginosa and Pseudomonas fluorescens were incubated in mineral salts media with diesel oil as the source of carbon and energy, at 28oC for 14 days in a Gyratory shaker at 200 rpm. Samples were withdrawn at 48-hours intervals, and centrifuged at 5000 rpm for 30 minutes. Biomass growth was measured on dry weight basis while diesel oil consumption was estimated from the supernatants after treatment with petroleum ether by spectrophotometric methods. The growth and substrate utilization parameters based on integrated balance analysis were obtained and the results obtained showed that P. aeruginosa and P. fluorescens, in both pure and mixed cultures propagated well on diesel oil. It was observed that within 5 days of incubation, 54%, 51% and 75% of the diesel was consumed by P. fluorescens, P. aeruginosa and the mixed culture, respectively. From the re-parameterized Monod Kinetic model, the Monod constant values obtained were 10.25, 22.84 and 2.64 gl-1 for P. aeruginosa, P. fluorescens and the mixed culture, respectively. The maximum specific substrate consumption rates of 1.008, 1.066 and 0.668 gg-1.day-1 were obtained for P. aeruginosa, P. fluorescens and their mixed culture, respectively. These results showed that with relatively higher percentage of degradation and lower maximum specific substrate consumption rate the P. aeruginosa and the mixed culture gave better degradation than the P. fluorescens.

Keywords: biodegrading-abilities, pseudomonas aeruginosa, pseudomonas fluorescens, mixed culture, diauxic growth, diesel oil

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