| The widespread presence of petroleum hydrocarbon contaminants in theenvironment had a serious threat to human health and a damage to the balance of theecosystem. In view of the serious harm of oil pollution, countries all over the worldare researching and developing a series of oil pollution treatment technology,Including physical, chemical and biological methods. Biological treatment technologyfor the safe, efficient, economic and no secondary pollution, without large equipment,attracts more and more people’s attention. The low bioavailability of petroleumhydrocarbons, becomes a limiting factor for biodegration. Adding surfactants canimprove the bioavailability. Biosurfactants was non-toxic and biodegradable, canincrease the solubility of hydrophobic organic compounds in the aqueous phase,increasing the mass transfer rate and bioavailability, which makes them widely used inthe hydrocarbon biodegradation.The fermentation conditions of the biosurfactant was optimized, the physical andchemical properties of the biosurfactant were analysed, the biodegradation of thecrude oil was investigated by GC-MS. The main conclusions are as follows:（1）Biosurfactants producing bacteria Lz-2was isolated from oil polluted watercollected from Dongying, Shandong Province, China, which was identified asbelonging to Bacillus through its physiological and biochemical experiments. Themetabolites were analyzed. Under the optimum conditions of sodium citrate30g·L-1,peptone5g·L-1, NaCl5g·L-1, pH=9, and temperature37℃, the surface tension canbe lowered from initial75mN·m-1to30.6mN·m-1, the biosurfactant production canreach about1.228g·L-1.（2）The biosurfactant produced by Strain Lz-2was glycolipid surfactant, the CMCof the biosurfactant was240mg·L-1.The biosurfactant had better stability while the temperature at the range of25-90℃, the salinity at the range of2%-10%, pH at therange of2-12. In addition, the HLB value of the biosurfactant was14.27, indicatingthat the glycolipid surfactant was suitable for organic solubilization.（3）The solubilization of polycyclic aromatic hydrocarbons （PAHs） by theglycolipid biosurfactant was investigated, which were mainly discussed biosurfactantconcentrations, pH, salinity and temperature on PAHs solubilization capacity. Theresults showed that the solubilities of naphthalene, phenanthrene and pyrene wereincreased linearly with glycolipid biosurfactant dose at the surfactant concentrationabove the biosurfactant CMC. The molar solubilization ratio （MSR） values weredecreased with increasing solute molecule, and following a decreasing order ofnaphthalene> phenanthrene> pyrene. The solubility of PAHs in glycolipidbiosurfactant solution was increased with pH and salinity, and reached the maximumvalue under the conditions of pH11, which the solubility of naphthalene was4.47mg L-1,phenanthrene was2.43mg L-1,and pyrene was1.6mg L-1.When theconcentration of salinity was8g·L-1, the solubility of naphthalene was2.27mg L-1,phenanthrene was1.57mg L-1,and pyrene was0.98mg L-1.The solubility ofphenanthrene and pyrene was increased with the temperature increasing, but thesolubility of naphthalene was increased firstly and then decreased, it reachedmaximum at30oC.（4） Crude oil was degraded by strain Lz-2, the components of the petroleumhydrocarbon was analyzed by GC-MS. The results showed that: crude oil got aconsiderable biodegradation by strain Lz-2in fermentation tank through seven days,the degradation rate can reach77.9%. In the expanding culture experiments, thedegradation rate of total alkanes was27.98%, the degradation rate of total polycyclicaromatic hydrocarbons was10.38%, the degradation rate of total biomarkers was8.50%. The order of the degradation rate was total alkanes> polycyclic aromatichydrocarbons> biomarkers, the results showed that the utilization of the simplestructure components such as alkanes was high, the utilization of the complexstructure components such as polycyclic aromatic hydrocarbons and biomarkers waslow. |
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