Fermentation Enhancement And Transcriptome Analysis Of Tuckahoe Triterpenes Regulated By Metal Ions

[Objective]To study the process of triterpenes production through Liquid-state fermentation of Poria cocos.Selecting out the optimum fermentation conditions by screening the best regulation of metal ions and conditions,optimizing the culture medium,and analyzing the transcript set.[Methods]1.Optimum regulatory conditions tudy:The dry weight of mycelium as well as triterpenes are treated as investigative indicators.Selecting out the best metal ions,the best concentration and the best adding time.2.Medium optimization study:On the basis of the optimum conditions,the box-benhnken experiment was used to design the optimum medium ratio.3.Transcriptome analysis study:The mechanism of zinc ions regulating poria cocos metabolism was analyzed by transcriptome sequencing,fingding the core sites of zinc ion-regulated triterpene synthesis in Poria cocos.[Results]1.Cell growth and triterpenes synthesis of Poria cocos were best promoted by adding 200?M ZnSO₄ at the fermentation time of 48h,and the results were DCW2.99g/L and triterpene 27.22mg/L.2.A four-factor and three-level response surface analysis was performed on the Poria cocos triterpenes fermentation medium using a box-benhnken experimental design,and the optimal medium was obtained:the glucose concentration was 25.81g/L,the yeast extract concentration was 9.90g/L,the potassium nitrate concentration was 7.50g/L,and the zinc sulfate concentration was 265.43?M.Under the optimal conditions,the yield of poria cocos triterpenes was 31.37±2.29mg/L.3.Five key genes involved in the regulation of terpenoid metabolism were identified by the transcriptome sequencing analysis.The proteins were terpene synthetase?metal ion binding domain?,polypropylene synthetase,?/?hydrolase and citrate transfer protein,respectively.The expression levels of terpene synthetase encoded by TRINITY_DN7529_c01_g1 and the?/?hydrolase encoded by TRINITY_DN10849_c0_g1 were up-regulated by zinc ion,especially terpene synthetase encoded by TRINITY_DN7529_c0_g1.Because it contains metal ion binding domains,It is assumed that the gene is a core site for regulating the synthesis of tuckahoe by zinc ion.[Conclusions]The method of controlling the liquid fermentation of Poria cocos by zinc ion to produce triterpenoids of Poria cocos is reasonable and feasible.The yield of triterpenes in Poria cocos could be greatly increased by optimizing the culture conditions.