Screening of Biosurfactant-Producing Bacteria Isolated from River Rido, Kaduna, Nigeria
Biosurfactants which are produced by microorganisms, are known to reduce the surface tension of viscous liquid. Among the roles of biosurfactants is solubilization of hydrophobic substrates especially petroleum. River Rido is a point where petroleum-rich effluents from Kaduna Refinery and Petrochemical Company are discharged. There is need to isolate and characterize bacteria capable of producing biosurfactant from River Rido, Kaduna, which will serve as a tool for bioremediation. Water samples contaminated with refinery effluents were collected from four different sites along River Rido. Biochemical tests revealed that the bacteria isolated from the water sample belong to the genera of Bacillus (36.36%), Pseudomonas (27.27%), Corynebacterium (18.18%) and Streptococcus (18.18%) species. The isolates were coded as BS1 – 11. Among the bacteria, 18.2% showed α-haemolytic activity, 54.5% showed β-haemolytic activity and 27.3% showed γ –haemolytic activity. BS1, BS2, BS4, BS6, BS7 and BS11 showed positive results for oil spreading test. BS1, BS2, BS4, BS6, BS7 and BS11 were all positive for the drop-collapse assay. Isolates BS1, BS2, BS4, BS6, BS7 and BS11 were able to emulsify crude oil. Analysis of Variance revealed that there is a significant difference in the emulsification activity of the isolates at various pH levels. Also, emulsification index of the isolates at varying temperatures are significantly different. This study revealed that Bacillus species, Corynebacterium spp. and Pseudomonas spp. isolated from River Rido have been confirmed biosurfactant producer with ability to produce assayable biosurfactants and can be useful tools for various environmental and industrial processes, especially in the area of bioremediation of oil pills.
Keywords: Biosurfactant, Emulsification, River Rido and Bacteria