The Study On Synthesis And Function Of Truffle Polysaccharide Enhanced By Diosgenin In The Process Of Solid-state Fermentation

Diabetes,as a chronic endocrine disease,has a growing number of patients.The diet therapy is one of the preferred methods to manage the occurrence and development of diabetes.Truffle is a kind of nutritious and precious edible fungus.It has various activities such as anti-oxidation,immune regulation,anti-tumor and hypoglycemic activity.How to safely and efficiently increase the biological active ingredients of truffle and to improve its bio-medical function is the bottleneck for developing truffle as functional food.To increase the key bio-active ingredients yield of truffles by the natural products is a better strategy.In the early stage,we discovered that diosgenin can increase the yield of truffle polysaccharides?TP?,change its structure,and increase its antioxidant activity in the process of liquid-state fermentation.The aim of the dissertation is to study the effect of diosgenin on the synthesis and function of t TP in the process of solid state fermentation.The main findings are as follows:?1?After compared with six grains,the oats was believed as substrate applied to solid-state fermentation of Tuber melanosporum.the optimum medium to increase TP yield by diosgenin included 60g oatmeal,1.8g fructose,1.2g sucrose,0.48g fishmeal peptone,0.72g yeast extract,0.06g MgSO₄,0.12g MnSO₄,0.09g KH2PO4,0.01g VB₂,and 0.45g Diosgenin.The optimum cultivation conditions included 19.2 mL inoculation volume,12.9 d cultivation time,26.6°C cultivation temperature,0.85water-materials ratio,15.2g corn bran.The final polysaccharide yield was 106.7±2.4mg/g,which was 5.6 times higher than before optimization.?2?Based on transcriptome analysis,diosgenin resulted in a total of 4482differential genes in truffles,including 1742 up-regulated genes and 2740down-regulated genes.KOG differential gene classification shows that differential genes are mainly distributed in general function prediction,post-translational modification,and protein turnover;GO enrichment analysis shows that differential genes are mainly distributed in metabolic processes,cellular processes,and single biological treatment processes;KEGG analysis of differences Genes mainly involve metabolic processes,cellular processes,environmental information processes,organic systems,and genetic information processes.The mechanism of TP yield increase and structure change was obtained by analyzing the expression of some key enzymes in the process of polysaccharide synthesis?3?After comparing the activities of TP and STP,TP and STP possess antioxidant activity and to control hypoglycemic activities.The ability of the antioxidant power and inhibitory action to?-glucosidase and?-amylase of STP is higher than those of TP.The kinetic analysis to scavenge DPPH·showed that increased DPPH scavenging rate of STP is depended on the increase fo the maximum reaction rate.The result indicated that STP itself has higher DPPH·scavenging ability.The improvement of ferric reduction antioxidant activity caused by STP was depended on the increasing their maximum reaction rate and affinity to substrate.The kinetic analysis to inhibit·OH generation showed that the inhibition of·OH generation and?-amylase by TP and STP was contributed to competitive inhibition,while the inhibition of?-amylase was anti-competitive inhibition.