SCREENING OF BIOSURFACTANT-PRODUCING BACTERIA FOR DEGRADATION OF PETROLEUM HYDROCARBON AND ITS DEGRADATION CONDITIONS

A biosurfactant-producing strain，named XJBM，was isolated from the oil contaminated soil of Karamay of field in Xinjiang，with crude oil as the sole carbon and energy source via enrichment culture． XJBM was identified as Pseudomonas Aeruginosa based on morphology，physiological and biochemical characteristics and the analysis of Biolog system． Glycolipid was found as the main components of the produced biosrfactant，which was examined by thin-layer chromatography． Under the optimal fermentation conditions，the yield of biosurfactant produced by XJBM could reach 2. 25 g /L． This biosurfactant could reduce the surface tension of culture broth from 68. 20mN/m to 32. 50 mN/m and emulsify paraffin oil to an appreciable level ( E24 = 81. 8%) ． The results of the single factor experiments showed that the optimum degradation conditions for strain XJBM were as follows: initial pH of 7. 5，temperature of 30 ℃，salt concentration of 5 g /L and inoculation amount of 10%． Under that condition，the degradation rate of strain XJBM for oil concentration with 1 g /L was 63. 78% after 7 days at shaking rate of 150 r /min．