Study On Production Of Mycelium And Polysaccharides Of Inonotus Obliquus Fermented In Liquid Medium Of Raw Materials Of Three Kinds Of Agricultural Products

Inonotus obliquus is a rare medicinal fungus that mainly parasitic on birch,silver birch,eucalyptus,alder,etc.It is rich in bioactive ingredients,such as triterpenoids,polysaccharides,polyphenols,lignan,melanin,etc.It has a variety of pharmacological effects,such as anti-tumor,anti-virus,anti-oxidation,hypoglycemia,hypolipidemia,Immunoenhancement,etc.The growth rate of wild Inonotus obliquus is extremely slow,and the natural resources are expensive because of its scarcity.Liquid fermentation technology has the advantages of short production cycle,high yield,less restrictions of season,and a wide range of fermentation raw materials.It can be used as a reliable way to obtain the mycelium raw materials and other metabolites of Inonotus obliquus.The mycelium of Inonotus obliquus has rich nutritional substances,which can replace the wild fruiting body to alleviate the shortage of fruit body resources of wild Inonotus obliquus.The annual yield of rice flour,soybean flour and wheat bran is high,and they are rich in nutrients.It is worth further exploring their deep processing development and utilization.Especially,the high efficiency and high value utilization of wheat bran with low price needs to develop new technology.Therefore,the theme of this study is to obtain mycelium and polysaccharides by using the liquid fermentation bran medium of Inonotus obliquus and adding rice flour and soybean powder in appropriate amount,which will provide theoretical and technical support for the possible practical application.Therefore,The detailed contents and results are as follows.（1）The optimization of liquid fermentation medium for Inonotus obliquusThe effect of the addition of wheat bran,rice flour,soybean powder,KH₂PO₄ and MgSO₄·7H₂O on the fermentation indexes were studied on the basis of single factor and U₂₄（24⁵）uniform experiments design.Regression analysis of the test indexes was carried out by using SPSS software,and the regression equations of mycelial dry weight and mycelial polysaccharides weight were obtained.The optimal medium composition of each index was obtained by the regression equations based on the exploitation and utilization of wheat bran.The fermentation conditions were determined to be rotation speed of 150r/min,temperature of 28℃,time of 7 days.Taking the mycelial dry weight as index,the100mL optimal medium compositions were as follows:4.8g wheat bran,2.4g rice flour,2.4g soybean flour,0.015g KH₂PO₄,0.015g MgSO₄·7H₂O,the mycelial dry weight was3.679g.Taking the mycelial polysaccharides weight as index,the 100mL optimal medium compositions were as follows:4.8g wheat bran,2.4g rice flour,2.4g soybean powder,0.36g KH₂PO₄,0.015g MgSO₄·7H₂O,the weight of mycelial polysaccharides was 0.250g.（2）The growth kinetic model of mycelium by liquid fermentation of Inonotus obliquusThe growth dynamics of Inonotus obliquus by liquid fermentation was studied.The results showed that the growth curve was approximately S-shaped.According to the design table of U₂₄（24⁶）,the uniform design experiments were carried out to study the effect of wheat bran,rice flour,soybean powder,KH₂PO₄ and MgSO₄·7H₂O and time on the results of fermentation.The empirical kinetic equations of mycelial dry weight was obtained by regression analysis with SPSS software.Based on the mycelial growth empirical kinetic equation,the mycelial dry weight of 20 groups in the U₂₀（20⁵）uniform design table were predicted.The expressions of the model parametersμ_m and C_x,_maxax in Logistic model were obtained by nonlinear regression with SPSS software,then the mycelial growth theoretical kinetic model by liquid fermentation of Inonotus obliquus was obtained.（3）The extraction of mycelial polysaccharides from Inonotus obliquus by enzymatic hydrolysis ultrasonic methodUnder the conditions of fixed enzyme dosage,ratio of material to liquid,enzymatic hydrolysis temperature and pH.The effects of enzymatic hydrolysis time,ultrasonic power and ultrasonic time on the yield of mycelial polysaccharides from Inonotus obliquus were studied by multi-sample experiment.The linear regression model of polysaccharide yield was obtained by SPSS software.Combined with the results of linear programming and experimental data,the optimal extraction conditions of polysaccharides were obtained as follows:material to liquid of 1:50,cellulase addition of 3.0%,pH natural,enzymatic hydrolysis time of 75 min,ultrasonic power of 300 W,ultrasonic time of 15 min.Under these conditions,the extraction rate of polysaccharides was not less than 7.2%.（4）Qualitative characterization of mycelial polysaccharides and determination of amino acid composition and heavy metal content of mycelium from Inonotus obliquusThe qualitative properties of mycelia polysaccharides from Inonotus obliquus was determined.The results showed that the polysaccharides was non-starch polysaccharides.The compositions and content of amino acids in fermented mycelium were analyzed.The results showed that the species of amino acids in mycelium are multiple and the content of amino acids is high.17 kinds of amino acids were detected,the total content of amino acid is 3.926g/100g dry mycelium,which contained 7 kinds of essential amino acids.The contents of heavy metals and arsenic in mycelium were determined by inductively coupled plasma mass spectrometry（ICP-MS）.The results showed that the content of Pb,As,and Cd in mycelium is 0.294mg/kg,0.0175mg/kg,0.0534mg/kg respectively.Hg was not detected,which are lower than the limited standard of health food.The content of Cr is 6.79mg/kg,which needs to be reduced by blending or post-treatment.