Abstract: Petroleum spill has caused serious environmental problems and enormous economic losses. The microbial bioremediation have been shown to be the most effective way for the removal of petroleum pollution in environments. We isolated a biosurfactant producing and petroleum degrading bacteria from petroleum contaminated soil in the region of Qilian Mountain Baoping River in the Qinghai-Tibet Plateau. We further investigated the petroleum emulsifiability, degradation properties, and degradation conditions of the isolated strain, as well as the uses of hydrocarbons with different carbon chain by the isolated strain. A biosurfactant producing and petroleum degrading strain, assigned as 23-1, was successfully isolated on the medium with petroleum as sole carbon source using the blood plate screening method. Morphological and 16S rRNA gene sequence analysis identified this isolated strain as Lysinibacillus fusiformis strain 23-1. The colorimetric and ultrasonic analysis indicated that the emulsifiability and emulsion stability of strain 23-1 were 19.6% and 37.5%, respectively, suggesting that L. fusiformis strain 23-1 can reduce the oil-water interfacial tension and enhance the oil solubilization. The gravimetric method analysis showed that 57% petroleum added in the medium could be degraded by L. fusiformis 23-1after 8-d incubation, with pH 7.5 and 25 ℃. Further GC-MS measurement indicated that L. fusiformis 23-1 strongly degraded direct chain saturated alkanes, partly degraded the short chain alkanes and long chain alkanes, but weakly degraded the aromatic hydrocarbons. L. fusiformis 23-1 can produce certain biosurfactant and degrade petroleum during growth in the medium added with petroleum as sole carbon source. This strain could be used for bioremediation of petroleum contaminated environments.

Key words: petroleum degrading bacteria, Lysinibacillus fusiformis, biosurfactant, petroleum degradation properties