Production of biosurfactant and its role in the biodegradation of oil hydrocarbons.

Based on indigenous bacteria from the oil-contaminated site of Dawu water source area in Zibo city of China, the production of biosurfactant and its role in the biodegradation of oil hydrocarbons have been investigated. Batch experiments were performed with paraffin as the sole substrate under temperature of 30 degrees C and pH of 7. Two high-effective species of bacteria (Z1 and Z2) were isolated. During the growth of both species, biosurfactants were produced, as indicated by the decrease of surface tensions of the enrichment medium from 61 to 45 mN/m. The critical micelle concentration (CMC) of Z1 ferment liquid was 0.4 (volume content). When reaching the CMC, Z1 ferment liquid demonstrated the effect of dissolution enhancement, that is, it could enhance the dissolved concentration of phenanthrene to above 1 mg/L, which was higher than the saturated solubility of phenanthrenene under standard condition. Elementary identification results revealed that both Z1 and Z2 belongs to bacillus. Z1 was 0.5 microm in diameter, 0.5-3 microm in length, and bearing flagellum, while Z2 was 0.2 microm in diameter, 0.5-1 microm in length and no flagellum.