Study On Biological Characteristics And Polysaccharides Of Isaria Farinosa CH7

With the decrease of wild Cordyceps sinensis resource and the increase of consumer demand, to find the substitutes, explore simple and feasible artificial cultivation technology and research the biological activities has led a boom. This strain which separated and purified from the field is a fungus. It is found to have a good fruiting body when cultivated on silkworm chrysalis and grain raw material. When it is cultivated in liquid culture, the growth period is shorter, the character is stable, besides and the sugar yield it produces is higher. A combination of traditional method and molecular biology method is used to study the biological characteristics of this strain. Evolutionary tree is built to study the relationships between the strain with other types; different vaccination ways on different hosts is used to discuss its life cycle; according to the mycelial biomass and exopolysaccharide content, the fermentation conditions are optimized. On the basis of preliminary exploration, their moisture moisturizing properties and the strength of the antioxidant activity in vitro of exopolysaccharides (EPS I, EPS Ⅱ) and intracellular polysaccharides (IPS I, IPS II) are explored. The main research contents and results are as follows:1) Biological characteristics analysis of Isaria farinosa CH7:the strain is identified belongs to Paecilomyces by means of morphological description and ITS sequence analysis, the pattern and 99% DNA are same, which is named Isaria farinosa CH7, the evolutionary tree of the strain is closely related to the strains which belong to the same genus. According to Koch’s postulates, the mycelium by liquid culture infects the tussah pupa and castor silkworm chrysalis by the means of injection, can grow fruiting body which can process with the original sample on the same strain, on this basis, the life cycle is realized. Besides, the growth state in different culture medium after sterilization is studied. Through different artificial medium about the solid culture of silkworm chrysalis, grains and liquid culture of conical flask, it is found that the fruit body quality and quantity are ideal. Liquid culture cycle is short; the production product is higher, which has a wide development prospect.2) Liquid culture optimization of Isaria farinosa CH7:According to the mycelial biomass and exopolysaccharide content, the optimized fermentation conditions of I. farinosa CH7 are as follows:sucrose 2.5%, beef extract 0.8%, initial pH 4.0 and fermentation at 28℃. The highest production of mycelium biomass yield and exopolysaccharide content are increased by 15.01% and 60.41% than before optimization, respectively. In the process of 30 L fermentation tank, the mycelium biomass and polysaccharide content is increased by 7.98% and 10.72% than in the conical flask cultures. Liquid culture has many advantages, such as the liquid culture conditions are more easy to control, the metabolic product is easy to extract, its product is not limited by time, location, season, etc, can be large-scale promoted in production practice, which can provide sufficient raw materials in production and research.3) The function analysis of polysaccharides about Isaria farinosa CH7:There are many products related cosmetics based on the efficacy of polysaccharide, which has been used on the market sales and circulation. To explore the practical value of I. farinosa CH7, the hygroscopic and moisture capacity and antioxidant activity are the evaluation about its function of intracellular and extracellular polysaccharides. In the experiment, studies have shown that the four polysaccharides all have certain moisture absorption and moisturizing ability, overall, the moisture absorption ability of intracellular polysaccharides is superior to exopolysaccharide and the moisturizing ability of extracellular polysaccharide is better than that of intracellular polysaccharide. By eliminating hydroxyl free radicals and chelating ferric ion ability to evaluate the antioxidant activity of polysaccharide, the results show that four polysaccharides all have the ability of scavenging hydroxyl free radicals and chelating ferric ion. The EC50 values demonstrate EPS II has strong antioxidant activity of obvious superiority, can increase the development and utilization in the future. In the later process of product development, the strengthening and mixed use of the polysaccharide can be considered, these exploration for I. farinosa CH7 in high-end cosmetics provides possible to meet the market demand.It establishes the foundation for the further development of I. farinosa CH7 resource, realizing industrialized production, development related products and solving the contradiction between supply and demand, maintaining the ecological balance identification. These explorations have important academic, economic and social value.