Preliminary Study On The Production Of Tuber Polysaccharide By Submerged Culture Of Tuber Sinense K. Tao Et Liu

Truffle, known as"black diamond", has long been a popular folk in Europe because of their highly nutritional attributes. T. sinense was treated as the most potential Truffle in china. The intracellular polysaccharides isolated from fruiting body also have immunomodulating and antitumor activity. Submerged culture of Truffle is viewed as a promising alternative for efficient production of valuable metabolites and has received increasing attention around the world.A process for the production of Tuber polysaccharide by submerged fermentation of T. sinense was developed in this work. The effects of culture media and conditions on submerged culture of T. sinense for production of polysaccharide were investigated in shake flasks.For inoculation density within the range of 160～653 mg DW/L, a large inoculation density led to a high production of extracellular polysaccharides (EPS), the maximum EPS production of 1.97 g/L at the inoculation density of 653 mg DW/L while a level of only 0.97 g/L was obtained at 160 mg DW/L.Effects of carbon source were investigated then. The results indicated sucrose was best for the cell growth. The maximum cell density reached 14.97 g DW/L while a biomass level of only 4.65 g/L was obtained when lactose was used. The influence of initial sugar concentration (20～125 g/L) was also investigated. The results showed that an initial sucrose concentration of 80 g/L was beneficial for the cell growth as well as IPS production. The maximum dry cell mass and IPS production reached 22.81 g DW/L and 2.92 g/L, respectively. When the initial sucrose concentration exceeded 80 g/L, the average growth rate decreased while the production of EPS increased correspondingly and the peak (2.85 g/L) was obtained at the highest sucrose concentration (125 g/L).The results showed that Mg2+ and K+ were favorable for the EPS production. In contrast with basal fermentation medium, their productions were 4.29 g/L and 3.32 g/L , which were enhanced by 68.9% and 30.7%, respectively. At the range of Mg2+ concentration(5～50 mmol/L), the maxmum EPS production (4.17 g/L) was obtained at the highest Mg2+ concentration(50 mmol/L). While lowest K+ concentration (10 m mol/L) was favorable for both cell growth and polysaccharide synthesis.The result of Full Factorial Design indicated that the interaction between Mg2+ and K+ was beneficial for EPS production, at the lowest concentration of Mg2+ (30 mmol/L) and K+ (10 mmol/L), the production of EPS reached the peak (5.86 g/L).Under the best culture condition of our study, the maximum cell density of 21.99g DW/L was obtained, and the highest production of intracellular and extracellular polysaccharide was 2.23 g/L and 5.86 g/L, respectively. To our best knowledge, there were not any references reported on submerged culture of T. sinense at present.