Biodegradation of Escravos light crude oil by three indigenous bacteria, isolated from mechanic workshop in Lagos State Nigeria

Abstract

Introduction: Petroleum hydrocarbons can be degraded by microorganisms such as bacteria, fungi, yeast and microalgae. However, bacteria play an imperative role in hydrocarbon degradation. Microorganisms are endowed with metabolism machinery to use petroleum products as a carbon and energy source Aims: The aim of the study is to isolate hydrocarbon degrading bacteria from hydrocarbon polluted site (mechanic workshops) in Lagos state. Materials and Methods: The physical, chemical and microbiological properties of the three soil sample were analyzed using standard procedure. Hydrocarbon degraders were isolated on 1% crude oil mineral salt medium via enrichment technique. The best hydrocarbon degrader were identified on the basis of their colonial morphology, biochemical characteristics and complemented with analytical profile index (API) kit. Hydrocarbon degradation were monitored using total viable count and residual oil was determined by Gas Chromatography equipped with Flame Ionized detector (GC-FID). Results: Alkaline pH were observed for all three soil samples, the total nitrogen detected were 0.07, 0.04 and 0.1. The total heterotrophic bacteria (THB) estimated were 3 x 1010, 6.5 x 109 and 1.7 x 1010 cfu/ml while the total hydrocarbon utilizing bacteria estimated via vapour phase were 1.89 x 106 , 4x104 and 9.62 x 107 cfu/ml for Ikeja, Iyana-Iba and Mushin sample. The organisms had a generation time of 5.56, 9.09 and 10.9 (d), the degradation half-life were 3.85, 6.3 and 7.5 (d) respectively. Over 60% hydrocarbon degradation were determined within 10 days for all three isolates. The Gc-fid prints shows reduction in peak area of various hydrocarbon fractions with a decrease in pH of the medium. Conclusion: The study showed that hydrocarbon degraders are ubiquitously distributed in the hydrocarbon polluted soil sample. Their degradation potential can be optimized so as curtail the adverse effect of petroleum in the environment