Screening Of Marine Cold-adapted Petroleum Degrading Bacteria And Study On Its Surface Active Substance Production

The average temperature of surface seawater in winter in northern China is about 2 ? on average,and oil spills are frequent.Due to the low temperature that can lead to the persistence of petroleum pollutants and the difficulty of oil spill emergency work,the same degree of oil spill occurred if Low temperature conditions are more harmful.The use of thermophilic bacteria to degrade petroleum pollutants is an effective method to control marine oil spill pollution at low temperature.However,the currently screened strains capable of effectively degrading petroleum at about 0 ?are mainly screened from the polar marine environment and seldom isolated from China.The bioavailability of petroleum hydrocarbons is reduced under low temperature conditions.Bioactive surfactants can promote the dissolution,emulsification and dispersion of petroleum hydrocarbons,which can significantly improve the bioavailability of petroleum hydrocarbons.Therefore,oil-degrading bacteria with surface-active substances are particularly important for the bioremediation of oil-contaminated waters at low temperature.However,at present,oil-degrading bacteria that produce surface-active substances are concentrated in the bacteria at room temperature,and there are very few low-temperature bacteria.Therefore,the purpose of this study is to screen low temperature petroleum degrading bacteria from the marine environment of our country and to study their degradation performance on petroleum hydrocarbons and the production of surface active substances.The main research results are as follows:1?Four strains of low-temperature petroleum-degrading bacteria with surface-active substances were selected and identified as Pseudmonas sp.QXL₁,Halomonas sp.QXL-2,Halomonas sp.QY2,Halomonas sp.QY3.2?The four strains screened all can degrade petroleum hydrocarbon under the condition of low temperature.After 60 days of initial crude oil concentration of 5 g/L,inoculum size of 10%?V/V?,0 ? and 120 r/min,compared with the control group without petroleum degrading bacteria,Degradation rate was significantly improved.Among them,Halomonas sp.QY-3 strain had the strongest ability to degrade crude oil,reaching 65.6%.After degradation for 30 d under the conditions of 1%?V/V?diesel inoculum,10%?V/V?inoculum,120 r/min and 0 ?,Than,diesel degradation rate increased significantly.Among them,Halomonas sp.QXL-2 had the strongest degradation ability to diesel fuel,reaching 62.9%.3?The four strains screened can produce bioactive surface active substances.Among them,the strain Pseudomonas sp.QXL-1 with the best surface-active property was able to reduce the surface tension of the fermentation broth to 42.4 mN/m and its E24 up to 53.3%compared with the control.The resulting surfactant had the lowest critical micelle concentration of 2.0 g/Land a surface tension of 35.1 mN/m at this time.The results of acid deposition and FT-IR showed that the surface active substances produced by the four strains were all glycolipid surface active substances.