Analysis of Crude Oil Degradation of Biosurfactant Produced by Citrobacter Murliniae and a Chemical Surfactant

In the past decades, biosurfactants have gained increasing attention due their low toxicity, biodegradability and environmental acceptability when compared with chemical surfactants. In this study, Citrobacter murliniae isolated from spent-oil polluted soil, produced biosurfactant when grown on mineral salt medium using 2% glycerol as the sole carbon source. The isolate was identified based on 16S rRNA sequence. Biosurfactant production was determined by drop collapse test, oil displacement test and emulsification index measurement. The biosurfactant produced by C. murliniae was able to reduce surface tension of water from 72mN/m to ~42mN/m, with critical micelle concentration (CMC) of 60mg/L. Assessment of emulsification activities of the partially purified biosurfactant produced by C. murliniae with various hydrocarbon substrates, gave highest emulsification index (E24) of 73.33% with palmoil, 70% E24 with crude oil and least E24 of 33.33% with fuel. On investigation of the crude oil degradation capacity, C. murliniae was able to degrade crude oil by 94%, it attained 96% crude oil degradation when the partially purified biosurfactant was introduced into the medium and 78% degradation when supplemented with Tween-80. This shows that biosurfactant has great potential to be used in bioremediation processes, especially in the petroleum industry.