Comparetive Study On Liquid Fermentation Of Cordyceps Sinensis Strains In Rice Bran And Wheat Bran Medium

Cordyceps sinensis, a kind of edible and medicinal fungi, contains a lot of active ingredients, such as nucleotides, cordycepin, polysaccharide, protein, amino acids, fatty acids, etc., with a variety of physiological functions, such as anti-tumor, antioxidant, anti-hyperglycemic, anti-hypolipidemic, improving immunity, etc. Therefore, Cordyceps sinensis culture mycelium can be used as materials to make high-value health food. China is a big country with rich rice and wheat. As the by-products of wheat and rice, rice bran and wheat bran are in high yield, but deep processing and utilization still remain to be further developed. To combine the value advantage of Cordyceps sinensis mycelium with the deep processing demand of wheat bran and rice bran, on the purpose of using Cordyceps fermenting liquid rice bran and wheat bran to produce more value mycelium, we aimed to reveal the results of existing strains and mutagenic strain fermenting liquid rice bran and wheat bran in whole and develop out of a new theory and technology on Cordyceps strains fermenting rice bran and wheat bran in whole by using comparative study. Therefore, research contents included the complementary technology and dynamic model of original strain, the new strain obtained through mutating, the technology and dynamic model of new strain, the physicochemical properties of new strain and the comparison of fermentation results between the new strain and the original strain. The contents, methods and results were as follows.(1) Study on the technology and dynamic model of original strain fermented wheat bran and rice bran in wholeU35(57) uniform design was used to study the effect of factors including the addition of wheat bran, rice bran, potassium dihydrogen, magnesium sulfate heptahydrate, rotation ratio, temperature and time on Cordyceps sinensis CFCC83924 fermentation, with the dry weight of mixture mycelium, mixture mycelial polysaccharide, expolysaccharide, pH and mixture wet weight as criteria. Five experience dynamic equations and one growth kinetic model were obtained with the aid of SPSS software through multiple linear regression and nonlinear regression. The results showed that:when the weight of wheat bran, rice bran, potassium dihydrogen phosphate, magnesium sulfate heptahydrate, rotation ratio, temperature and time was 8 g,8 g,0.15 g,0.15 g,150 r/min,20℃,5 d, respectively, mixture mycelial dry weight, the mycelial polysaccharide and expolysaccharide were reached 12.0 g,482.9 mg and 1439.2 mg in100 mL fermentation culture medium, respectively. Compared with the results of Cordyceps sinensis CFCC83924 fermenting liquid wheat bran and rice bran, which were the previous study of our research group, we obtained a wider range of fermentation parameters, the increased significantly target yield in 100 mL fermentation culture medium and put forward the new empirical and theoretical equations of fermentation kinetics, which could be used as a contrast of the follow-up study.(2) Study on new high efficient strain by mutationWith mixture mycelia dry weight, mixture mycelia polysaccharide weight and expolysaccharide weight as criteria, ultraviolet was used to mutate Cordyceps sinensis CFCC83924 to obtain a better Cordyceps sinensis mutagenic strain named Cordyceps sinensis JSU1401, through a series of screening steps, which included ten times initial screening, five generation of flat screening and five generation of fermentation stability screening. It found that the growth rate of the new strain was 1.4±0.03 cm/d and the mixture mycelia dry weight, mycelial polysaccharide weight and expolysaccharide weight was 3.8±0.06 g、198.1±26.09 mg、190.5±5.49 mg in 100 mL fermentation culture medium, respectively. Comparing with the original strain (1.2±0.05 cm/d、 3.7±0.06 g、 144.9±6.35 mg、145.8±10.15 mg), these criteria grew up by 18.9%、3.5%、36.7%、30.7%, respectively.(3) Single factor experiments of mutagenic strainWith mixture mycelial dry weight, mixture mycelial polysaccharide weight and expolysaccharide weight as criteria, four single factor experiments of Cordyceps sinensis JSU1401 fermenting liquid wheat bran and rice bran were done. The factors included the weight of wheat bran, rice bran, potassium dihydrogen and magnesium sulfate heptahydrate in 100mL initial fermentation culture medium. We found that the weight of wheat bran and rice bran had much significant effect on the three criteria, while the weight of potassium dihydrogen had significant effect on mixture mycelia dry weight and the weight of magnesium sulfate heptahydrate had significant effect on mycelial polysaccharide weight.(4) Study on the technology and dynamic model of mutagenic strain fermented wheat bran and rice bran in wholeU24(245) uniform design was used to study the effect of factors including the weight of wheat bran, rice bran, potassium dihydrogen, magnesium sulfate heptahydrate in 100mL initial fermentation culture medium and time on Cordyceps sinensis JSU1401fermentation, with the dry weight of mixture mycelium, mixture mycelial polysaccharide weight, expolysaccharide weight as criteria. Three empirical dynamic equations and one growth kinetic model were obtained with the aid of SPSS software through multiple parameters linear regression and nonlinear regression. The results showed that:when the weight of wheat bran, rice bran, potassium dihydrogen phosphate, magnesium sulfate heptahydrate and time was 4 g,4 g,0.25 g,0.0075 g,3 d, respectively, we could obtain more mixture mycelial dry weight, the mycelial polysaccharide weight and expolysaccharide weight, which was 7.0 g,404.4 mg,878.6 mg in 100 mL fermentation culture medium, respectively. Comparing with the original strain fermenting results (5.5 g、337 mg、828.9 mg) on the same condition, these criteria improved by 27%, 20% and 6%, respectively. The fermentation technology and kinetic model of the new strain can provide as the theoretical guidance and the basis for the calculation of parameters selection. However, because of its narrow scope of application (1) of the original strains, it was impossible to compare the value of both at the upper limit(5) Study on physical and chemical properties of mutagenic strainStudying the physicochemical properties of Cordyceps sinensis JSU1401 mycelial polysaccharide, we found that the polysaccharide which showed strong antioxidant activity evidenced by scavenging abilities of DPPH and reducing powers, was none starch polysaccharide and without or having few protein and amino acid. And the activities increased by the concentration. The mycelial polysaccharide we obtained was the same kind with the original strain and had similar reducing power. It also made an additional instruction of DPPH clearance ability.