Facultative thermophilic microorganisms were isolated from oil and water samples from Malaysian oil wells. The isolated microorganisms grow in an enrichment medium containing kerosene (hydrocarbon) as the source of carbon and energy. Batch-growth kinetic studies were carried out in a 500 ml shake flask and the production of biosurfactant and biopolymer were found to be cell growth associated. Two of the isolated microorganisms (S24A and S21A) are capable of producing biosurfactant in sucrose and glucose containing medium. These are indicated by the reduction of interfacial tension (IFT) of the supernatant. These two strains obtained the IFT reduction in both sucrose and glucose medium for more than 20 dynes/cm. Strain S19 and S12A can reduce the surface activity of growth medium only in sucrose and glucose medium respectively. Strain S19 can reduce the IFT of sucrose growth medium for 25.27 dynes/cm and no decreased in surface tension and interfacial tension were observed when S19 was grown in glucose medium. Adversely strain S12A can only reduce the IFT of glucose growth medium for more than 30 dynes/cm. Another two isolated bacteria was found to produce biopolymer and increase the viscosity of supernatant from 1 cp to 4 cp are strain S13 and S17A. These isolates produce exopolymer like material when grown on agar medium containing 5% sucrose.

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