Screening Of Biosurfactants Producing Strain And Study On Degradation Of Petroleum

Surfactant occupies an important status in the industrial field,due to the chemical surfactant is more harmful to the environment,the use of surfactant is limited.Biosurfactants are amphiphilic nature of the secondary metabolites of microbial microbial growth process,a new green surfactants.The study of biosurfacants get attention in recent years Biosurfactants low toxicity,environmentally friendly features to make it widely use in various fields.There has a broad development prospects,especially in the oil exploration industry.In this study,trough enrichment culture,blood agar plate,crude oil plate,oil spreaing and surface tension determine screen a biosurfactants producing strain DGY-3.The strain was preliminarily identified as Bacillus by morphological observation and 16SrDNA sequence analysis.By the thin layer chromatography and infrared spectrum identified as Lipopeptide biosurfactant.The critical micelle concentration is 30mg/L,the emulsifying activity is 77.4%,in the pH 2-12,the temperature range of 50-120?,22%NaCl,CaCl2 concentration 3200mg/L still maintain good surface activity.The medium and culture conditions for produced biosurfactant Bacillus were optimized by single factor and orthogonal test.The optimized medium are soluble starch 20g/L,ammonum chloride 2g/L,KH2P?46g/L,K2HP?42g/L,MgSO4·7H2O 0.3g/L,NaCl 2g/L,CaCl20.08g/L.EDTA0.4g/L.Culture conditions are the 4%inoculum,seed age 16h,pH value7,culture temperature37?,shaking flasks speed 160r/min,culture time 48h.After optimizaion of the fermentation condition,the surface tension of fermentation broth reduces from initially 67.5mN/m to 24.8mN/m,and the yield of lipopeptide reached 1.08g/L.The effect of adding lipopeptide biosurfactants and inoculating lipopeptide product stain was investigated.,the lipopeptide biosurfactant effective to emulsify crude oil and form oil-in-water emulsion,Adding lipopeptides can enhance the degradation rate of crude oil,different crude oil degradation rates were increased by 21.0%and 19.8%respectively.