The Study Of Lipid And Carotenoids Production By Rhodosporidium Toruloides Mutant

The rapid development of industrial society today is accompanied by excessive exploitation and consumption of fossil fuels,which lead to environmental pollution,climate warming and energy crisis and many other issues.Looking for clean,sustainable development of new energy has become a hot research nowadays.Microbial oil as a kind of chemical,food and energy applications in the field of oil products have attracted the attention of researchers.Microbial oil,also known as single cell oil(SCO),is a saturated or unsaturated fatty acid triglyceride synthesized from yeast,mold,bacteria or algae and other microorganisms using carbohydrates,hydrocarbons or common oils as carbon sources under certain conditions.Microbial oil can be used as raw materials of biodiesel,which contain many advantages of short growth,no restriction by climate and geographical conditions.Furthermore,due to the richness of unsaturated fatty acids,microbial oil will become an important part of healthy food in people's growing demand for healthy food.Rhodosporidium toruloides is a oleaginous microorganism that has high accumulation of oil(cell dry weight of more than 40%)and wide range of substrate-producing.In this thesis,the type of linolenic acid in the oil of R.toruloidesACCC 20341 was identified as a-linolenic acid for the first time.The effects of nitrogen source and C/N ratio in the fermentation medium on the oil production of R.toruloidesACCC 20341 and R.toruloidesM18 were studied.Interesting results were obtained that the yield of R.toruloidesM18 was higher than that of R.toruloidesACCC 20341 in the same culture conditions and the total yield of R.toruloides M18 reach(12.4±0.2)g/L was determined by using tryptone and(NH4)2SO4 as nitrogen source and C/N ratio of 400:1.In the process of a-linolenic acid synthesis,R.toruloides ACCC 20341 and R.toruloidesM18 had the highest content of 4.7%and 5.67%respectively with glutamic acid and tryptone as nitrogen source and C/N ratio of 400:1.The binary vector pCAMBIA 1300-gpd-fad 15 containing the ? 15-desaturase gene was constructed by overlapping extension PCR and Gibson assembly.The R.toruloidesT transformants was successfully obtained by Agrobacterium tumefaciens mediated transform(ATMT).The contents of a-linolenic acid in oil and fat of R.toruloides M1 8 and R.toruloides T in the same conditions were 4.44%and 4.66%,respectively,Which indicated that overexpression of ?15-desaturase in R.toruloides could not increase the production of ?-linolenic acidR.toruloides can also synthesize carotenoids under appropriate culture conditions.The variation of the carotenoids synthesis of R.toruloides at the same time as the oil synthesis was explored.The results showed that the high C/N ratios in the culture medium were more favorable for the synthesis of carotenoids of R.toruloides.the total carotenoids yield of R.toruloidesACCC 20341 and R.toruloidesM1 8 were(11.62±10.2)mg/L and(24.09±0.02)mg/L,respectively.The relationship between the accumulation of oil and the synthesis of carotenoids was studied.The yield of carotenoids increased with the increase of oil production.