Screening Trichosporon Cutaneum Under Cellulase Stress By Ultra-high Speed Centrifugation And Microbial Lipid Fermentation

Microbial lipid fermentation using lignocellulose is one of the important ways to produce biodiesel raw materials.Trichosporon cutaneum is an oleaginous yeast which can resist the inhibition of lignocellulosic source and has excellent adaptability to lignocellulose.Screening methods for high-yield oil-producing yeast are generally complex and have low screening efficiency.Therefore,it is important to find a simple,fast,and high-throughput screening method without omission.In the previous research work,based on the principle of the density difference with different lipid content,high-speed centrifugal screening method was used to obtain the T.cutaneum MS 28 with increased lipid production.Microscopic observations show that T.cutaneum MS 28 has larger cell volume and thinner cell wall than the original strain,so it is speculated that there is a close relationship between cell morphology and lipid accumulation.The cell wall of Trichosporon cutaneum is mainly composed of dextran,mannan and a small amount of chitin.Cellulase can degrade glucan in the cell wall and affect biosynthesis.This article takes T.cutaneum ACCC 20271 as the starting strain and adds cellulase to T.cutaneum ACCC 20271 fermentation medium for long-term adaptive evolution.Results showed that T.cutaneum ACCC 20271 cells under cellulase stress rapidly changed its cell wall composition and cell morphology,the cell wall became thinner,and the cell volume became larger rapidly;T.cutaneum with thinner cell walls and larger volume has larger space for microbial oil accumulation,which is more conducive to the transfer of nutrients,biosynthesis and oil accumulation.Using ultra-high-speed centrifugal screening for the adaptive evolution of T.cutaneum under cellulase stress,a mutant strain T.cutaneum YY 52 with significantly improved lipid production was finally obtained.The fermentation performance of T.cutaneum YY 52 in the lignocellulose system was measured.When T.cutaneum YY 52 was fermented with wheat straw as raw material,the final lipid concentration reached 55.39 g/L.When fermented with corn stover as raw material,the final lipid concentration is as high as 58.39 g/L.Both fermentation indicators are currently the highest levels of microbial lipid production by lignocellulose.Lipid are intracellular products,and the difficulty in extracting lipid is one of the main problems restricting the industrial application of cellulose lipid.Cell wall rupture is not only time-consuming but also costly.This article attempts to add cellulase to the T.cutaneum fermentation medium.While obtaining high lipid production,the cells rupture due to the extremely thin cell wall in the late stage of fermentation,making it easier and faster to extract the oil.In summary,in this paper,by adding cellulase to the adaptive evolution medium of T.cutaneum,the cell morphology is rapidly changed,and lipid accumulation ability is enhanced.The ultra-high speed centrifugal screening method is used to finally screen a high-yield lipid yeast T.cutaneum YY 52,which achieves high-index cellulose microbial lipid fermentation,this method provides a new idea for improving the production of microbial lipid and microbial intracellular products...