Studies On Selection Of High-yield Oil Mutants Of Oleaginous Yeast And Technological Parameters Of Industrialized Production Of Microbial Oils

Traditional oils and fats were mainly from animals and plants,and there are a lot of disadvantages which are seriously restricted its large-scale industrial production, including unsteady yield,long process,and huge costs.Therefore,many countries are seeking and developing renewable resources.Microbial oils is as a new kind of green resource with excellent environment protection which will have a good prospect.Purposes:The goals of study was to obtain a high-yield microbial oils strain from a lot of yeast by different mutagenesis techniques.In order to improve the efficiency of the biomass and lipid production,it was optimized the fermentation conditions in fermentation medium.At the same time,potato starch hydrolyzate as carbon was used to cultivate the mutant strain,which can provide a reference for large-scale industrial production and treating potato starch waste fluids.Methods:Using ultraviolet irradiation and nitrosoguanidine mutation treatment methods were to get a high-yield lipid and test its genetic stability.The strain which cultivated in fermentation medium with glucose as carbon was used to get the best fermentation condition by optimizing.Under the optimum conditions,the strain has been studied its biomass,lipid production and fatty acid composition in potato starch hydrolyzate as carbon in the fermentation medium.Results:(1)In this experiment,oleaginous yeast EAM-AC16 (CGMCC 7429) was selected which can accumulate much more biomass and lipid after several rounds of mutation breeding.And it was Trichosporon mucoides by molecular identification. (2)The optimum fermentation condition for the highest lipid production were glucose concentration 82.47g/L,fermentation time 146.4h,quantity of inocultation 9.45%, fermentation temperature 30 ?.initial pH 6.0,install fluid 70mL/250mL,and ammonium sulfate lg/L,and lipid production was 5.204g/L.(3)The response surface methodology was used to optimize the potato starch hydrolysis conditions:potato starch concentration 20mg/mL,ratio of enzyme dosage to dry starch of 3.2%,enzyme ratio of a-amylase and glucoamylase 2.17:1, initial pH4.06 and reaction time 4.28h,and the glucose concentration was 15.061mg/mL in hydrolyzate.(4)Under the optimize fermentation conditions,strain EAM-AC16 was cultivated in fermentation medium which potato starch hydrolyzate was as carbon.At last,the biomass was 15.135g/L,lipid production 5.261g/L in 250mL flask;In 5.0L fermenter,biomass was 14.276g/L, lipid production 5.105g/L.(5)The microbial oils from strain EAM-AC16 was comprised of C16 and C18 fatty acids with different carbon source in fermention medium,which mainly contain palmitic acid, linoleic acid, y-linolenic acid and elaidic acid.