Isolation And Screening Of Degrading Strains And Construction Of Microbial For Lubriacan-castor

Lubricant-castor is a kind of green lubricants with excellent biodegradability. It can bedecomposed into small molecules by microorganism and reduce the pollution ofenvironment. Therefore, it has significance and application prospects for oil pollutioncontrol to screen natural strains and constructing a microbial consortium. In this study,oil-polluted soil in DaGang oil field was chosen as experimental material, and strains whichcould degrade the waste lubricant-castor were acquired after enrichment、separation andscreening。The traditional weight method and the improved weight method were used todetermine degradation rate, and gas chromatography-mass spectrometry(GC-MS) was usedto evaluate the composition of degradation products. Then, a high-effective microbial florawas constructed. It would provide a theoretical basis for the practical applications ofmicrobial degradation by kinetic analysis.Six strains of bacteria which could degrade the waste lubricant-castor are screenedfrom oil-polluted soil in DaGang oil field, and named B1、B2、B3、B4、B5、B6. It wasweighting the oil after extraction and calculating the degradation rate by traditional weightmethod, and the degradation rates of the six strains of bacteria were22.3%、31.7%、64.9%、72.4%、26.9%、28.5%. In the improved weight method, extraction was replaced bycentrifugal refrigeration method, and the degradation rates of the six strains of bacteriawere27.6%、42.5%、68.2%、81.5%、33.8%、37.6%. Besides, biodegradability index BDIof B6which could produce CO2was82.37%by the rapid determination.Lubricant-castor is a mixture of a variety of substances by GC-MS, and there are foursubstances with high level. Diisooctyl sebacate was the most one as base oil, and the otherthree substances were components of additive. B4mainly degraded the base oil, B5mainlydegraded the components of additive, and B6could completely degrade to produce CO2, sothe optimal combination was confirmed as B4+B5+B6with86.9%as its degradation rateby the improved weight method.The concentrations of residual oil were determined during12consecutive days, andthe degradation rates were calculated. The biodegradation regularity model was fitted likethat for it met exponential equation between the concentrationsof residual oil and degradation time. The biodegradation regularity model was fitted like that v(t)=1.199t/(2.4441+t) for it met hyperb.lic vel.city model between the degradation rate and degradation time.95％was chosen as the confidence level for regression testing kinetic model by F-test,and the regression results were Obvious.