PRODUCTION AND CHARACTERIZATION OF BIOSURFACTANTS BY ISOLATES FROM LUBRICATING OIL POLLUTED SOIL

Abstract

The study intended to isolate, Produce and characterize biosurfactant producing isolates from spent lubricating oilpolluted soil. The isolated bacteria were identified as Acinectobacter iwoffii mpe25 and Micrococcus kristinea mpe12. Both bacteria exhibited the ability in producing biosurfactants as evidenced by blood haemolysis, oil displacement, and drop collapse and emulsification activities. After the fermentation for seven days, biosurfactant from the two bacteria was successfully extracted from the fermentation by centrifugation and purified by solvent extraction using acid precipitation method. Characterization of the biosurfactants was done by thin-layer chromatography (TLC), gas chromatography and mass spectroscopy (GC-MS), and Fourier transforms infrared (FTIR) spectroscopy. The bacteria lysed red blood cells by forming cleared transparent halos (beta haemolysis) around the colonies caused the wide diameter of oil displacement of 5.5cm, 6.10cm, and high emulsification capacity of 74.5% and 65.0 % respectively. The GC-MS revealed the presence of palmitic acid, 15-hydroxypentadecanoic acid, 2, 3- dihydroxydodecanoic acid, sulfur-dodecyl-2-ethyl hexyl ester; the FTIR revealed important functional groups (S=O, C-O-C, C=O) that defined the biosurfactant to be a glycolipid with a unique sulfonyl group in both biosurfactants. These led to the assigned name of sulfoglycolipid Bios-25 and disulfoglycolipid Bios-12 to the biosurfactant produced by A. iwoffii mpe25 and M. kristinea mpe12 respectively. Due to the high emulsification capacity of these biosurfactants, it is recommended for use in bioremediation studies.