Preliminary Study On Solid State Fermentation Of Streptomyces Strain Men-myco-93-63

Streptomyces roseoflavus strain Men-myco-93-63 was isolated from potato scab declined soil,which showed strong antagonistic abilities on many plant pathogens,such as Verticillium dahliae,Bipolaris sorokiniana,Botrytis cinerea,Vegetable root-knot nematodes and so on.In greenhouse and field test,Men-myco-93-63 and its fermentation showed a good control effect on cucumber powdery mildew,and the control effect was up to 90%in the field.In this research,sporulation of Men-myco-93-63 was used as the evaluation index to study the effect factors of solid state fermentation of the bio-control strain,including of nutritional substrate,formula of fermentation medium,culture conditions,and extra nutritional conditions,which would provide scientific technical parameters and basis for the biogen research and its commercial production.At first,the formula of solid state fermentation media were determined.The sporulation of Men-myco-93-63 on different substrates,such as wheat bran,millet bran, cornstalk meal,cornmeal,combits,mille,rice,sorghum,black rice,barley,oat,and oatmeal were investigated,and there were six kinds of substrates adapted to the production of spores,including rice,millet bran,cornstalk meal,sorghum,barley,and black rice.Then, the sporulation of Men-myco-93-63 on different substrate mixtures was tested,and there were 4 substrates adapt to spores production.The suitable medium which contains rice, sorghum,millet bran,and rice hull with the proportion of 2:2:3:3 was selected and optimized for the spore production of Men-myco-93-63 by orthogonal experiments.Rice hull was used as filling material to increase the ventilation amount.To determine the cultural conditions,initial ratio of water contents,state amount added,inoculation quantity,and culture temperature were tested by single-factor experiments and orthogonal experiments.The appropriate parameters were as followed:the initial water vs.state material was 15 g in 500 mL erlenmeyer flask;initial ratio of water content was 1.7:1.0(v/w,rice hull excluding),inoculating quantity was 7 mL,culture temperature was 28℃.On this basis,the fermentation time and initial pH as effect factors were selected by single factor experiments,and the conditions were determined as that the optimal fermentation time for sporulation was 10 d,and the optimal pH was natural. Finally,based on the screening of nutritional substrate,formula of fermentation medium,and culture conditions,the extra nutritional conditions were tested.The effects of adscititious carbon source,such as glucose,cane sugar,and maltose,nitrogen source,such as peptone,urea,KNO₃,and NH₄NO₃,and inorganic salt,such as Na⁺,K⁺,Zn²⁺,Fe²⁺, Mg²⁺,and Ca²⁺on the sporulation of Men-myco-93-63 were tested.The results showed that,adding 1.0%glucose and 2.0%peptone,or 0.1%Ca²⁺salt could improve the sporulation obviously.