Characterization And Application Of Biosurfactant Produced By Cold-Adapted Bacteria Planococcus Sp.XW-1

In northern China,the temperature of surface sea water is low in winter,and oil spills often occur.Low temperature reduces the bioavailability of petroleum pollutants.Although bioremediation methods have the outstanding advantage,low temperature is the bottleneck that limits the degradation of petroleum hydrocarbons.Therefore,petroleum-degrading bacteria that can use petroleum hydrocarbons as carbon source to produce surface-active substances at low temperatures was screened from northern sea of China.Focusing on the properties' of the surface-active substances and its potential for application in bioremediation of oil pollution,mainly including the solubilization,promotion degradation and elution of petroleum hydrocarbons,and the effect of the addition of biosurfactants on the bacterial community in seawater.The main research results include:1.A strain of marine low-temperature petroleum-degrading bacteria was selected and named as Planococcus sp.XW-1.The strain XW-1 can produce biosurfactant with petroleum hydrocarbon as the sole carbon source at low temperature.The biosurfactant has low critical micelle concentration(60 mg/L)and low surface tension(26.8 mN/m).It has stable performance under conditions of salinity(1%?18%),pH(2?12)and temperature(-18?105?).After TLC and FTIR analysis,it was identified as a glycolipid biosurfactant.2.The surface-active substances produced by the strain Planococcus sp.XW-1 can significantly promote the solubility of petroleum hydrocarbons in water and the degradation of crude oil.After adding 240 mg/L(3xCMC)biosurfactant,the dissolved amount of phenanthrene,pyrene,diesel oil and crude oil increased by 430%503%,505%and 600%respectively.When the biosurfactant concentration exceeded CMC,WSRphenanthrene(0.0234)>WSRpyrene(0.0165)>WSRdiesel oil(0.0015)>WSRcrude oil(0.0027).After adding biosurfactant,the degradation rate of crude oil in seawater increased from 54%to 73%;the degradation rate of crude oil in sand-water mixture increased from 65%to 86%.3.After adding the biosurfactant,the crude oil adsorbed on the sand with different particle sizes was significantly eluted,and the elution rate increased with the increase of the particle size.When the particle size was below 0.45 mm,the elution rate of crude oil increased from 17.1%to 87.9%.When the particle size of sand was above 2 mm,the elution rate of crude oil increased from 22.7%to 94.28%.4.With the addition of biosurfactants,the biodiversity of bacterial community and the abundance of Oleispira and Pseudoalteromonas increased significantly in oil-contaminated seawater.