Isolation and Screening of Spent Engine Oil Utilizing Bacteria for the Production of Biosurfactants

Abstract

This study was conducted to isolate and screen spent engine oil utilizing bacteria for possible production of biosurfactants from spent engine oil polluted soil in Dutse Mechanic village, Jigawa State. Pour plating method through the use of sterile nutrient agar medium enriched with spent engine oil as a sole carbon source was employed to isolate the desired hydrocarbonoclastic bacteria. Emulsification assay, foaming activity and blood haemolysis tests were conducted to screen biosurfactant producing bacteria. Out of the five bacteria isolated and screened, only two (S1 and S2) showed positive results with diameter of clear zone, 2.2 and 3.1cm respectively. Foaming stability in S1 was higher than that of S2. S1 recorded higher emulsifying activity (61.9%) than S2 (45.0%). S1 recorded β blood haemolysis while S2 was γ haemolysis. The isolated and screened hydrocarbonoclastic bacteria that demonstrated tendency to produce biosurfactants in this study are possibly Bacillus subtilis and Bacillus cereus based on the morphological and biochemical attributes displayed. However, molecular identification of the bacterial isolates screened in this study is recommended with a view to confirming their identity further.