| Sophorolipids is an important glycolipid biosurfactant with excellent solubility and emulsifying activity,foaming property,thermal stability,low surface tension,good performance,which has the research value and huge economic benefits and has been widely used in food,environmental governance,petroleum industry,chemical industry and medicine field.However,the low yield and high price of sophorlipids,therefore,it is of great significance to reduce the production cost and improve the production of sophorlipids.In order to solve the problem of low conversion rate of fat soluble carbon source,the optimization of fermentation technology and molecular biological methods are used to change the intracellular oxygen transfer and dissolution rate and to solve the problem of low yield.The Starmerella bombicola O-13-1 were added to shake flask and 5L fermentor with transgenic soybean oil and non-transgenic soybean oil and Corn oil No.1,corn germ oil as the fat soluble carbon source for the production of sophorolipids.The results showed that transgenic soybean oil is suitable fat soluble carbon source for the production of sophorolipids,the yield reached 58.59g/L,197.96g/L,respectively.In this paper,four kinds of fat soluble carbon sources were methylated and analyzed by GC-MS.The four kinds of fat soluble carbon sources were separated and purified.The structure was analyzed by HPLC-MS.The results showed that the fatty acid composition of four kinds of oil were C16:0,C18:0,C18:1,C18:2,difference C18:0do not contain fatty acids 1,corn oil and corn embryo oil;fatty acid composition of sophorolipids produced by the difference is not large,fatty acid composition and content respectively: The transgenic soybean C18:0(15%),C18:1(53.9%),C18:2(20.7%),non-transgenic soybean oil(C18:0 15%),C18:1(53.9%),C18:2(20.7%),corn germ oil,C18:0(8.7%)C18:1(58.2%),C18:2(21.7%),corn oil 1 C18:0(12.9%)C18:1,(53.5%),C18:2(21.9%),and fat type sophorolipids is the highest content with more than 70% among of lipid types.In the transgenic soybean fat soluble carbon source,the highest production ofsophorolipids reached 59.39g/L with shake flask fermentation when pH=6.As the fermentation kinetics showed,the cell growth achieved steady stage and began producing sophorolipids when time reached 30 h,and the fermentation reached mid index at 96 h,sophorolipids yield reached the highest and as the best time for the end of fermentation at 108 h.Using mono factor experiment to optimize the fermentation process of sophorolipids,results show that the constant p H is 3.5,with the continuous flow of genetically modified soybean oil yield of sophorolipids is 139.06g/L;the speed 450r/min,sophorolipids output 186.55g/L;ventilation quantity is 1.5VVM,sophorlipid yield was 197.96g/L;the dissolved oxygen content of 50%,sophorolipids yield was 192.37g/L;64h before fermentation temperature is controlled at 30 ?,then the temperature at 25 ?,sophorolipids yield is 216.37g/L.At the end of fermentation,the fermentation broth after removal of the precipitate product showed good surface activity and low critical micelle concentration(CMC),which was about 192mg/L.All have good salt tolerance(3-24%),strong acid and alkali resistant(p H2-8)and high temperature(boiling water for 120min)performance;emulsification index of n-hexane and sixteen were respectively 57.5% and 67.5%,cut also has good emulsification in strong acid,strong alkali,high temperature and high salinity.The expression vector of the yeast Starmerella bombicola was constructed using the modern molecular biology gene recombination technology in this paper,in order to obtain a stable and high yield recombinant engineering strain. |
PDF Full Text Request