Abstract: Indigenous microbial strains of the soil were habituated by adding thick oil intentionally. Thirtythree bacterial strains were isolated with thick oil as the carbon source alone. Two higher biosurfactant producedstrains and nine higher thick oildegrading strains were screened from all the isolates. The biosurfactants produced by strain XJ1 and SJ4 in the fermentation broth could reduce the surface tension of water from 72.4 mN/mto 36.1 mN/mand 36.2 mN/m respectively. In the process of inoculating the two strains, the rates of thick oildegradation were 35.89% and 31.59% after treatment for 14 days. For strains XJ1 and SJ4, the relation between biology quantity and the surface tension of fermentation broth was studied simultaneously. Infraredspectral analytic results show the biosurfactants are both kinds of glycolipid.

Key words: biosurfactant, thick oildegrading bacteria, bioremediation of contaminated soil, thick oil