Solid Fermentation Conditions Of Streptomyces Roseflavus Men-myco-93-63 And Its Control Effect On Root-knot Nematode Disease

In this study,the the solid fermentation substrate and the fermentation conditions for Streptomyces roseoflavus Men-myco-93-63 were screened and the storage stability of the solid fermentation products was measured.Through greenhouse and field experiments,the effect of corn grits solid fermentation on vegetable root-knot nematodes was tested as well as the quality and yield of watermelon and cowpea.The results were as follows:Through single factor and orthogonal experiments,the best solid fermentation medium formula and conditions of Streptomyces roseflavus Men-myco-93-63 were finally determined.Corn grits was selected from the three solid substrates of corn grits,rice and sorghum with the diameter of corn grits 3-5 mm,the ratio of rice husk char(m):corn grits(m)1:4,the inoculation amount 10%,the fermentation time 7 days,the substrate thickness 2 cm or 3cm,the initial water ratio 0.8:1,and the pH value 7-8 being the best.Under these conditions,the sporulation of the corn grits solid fermentation products of Streptomyces roseflavus Men-myco-93-63 was 1.16×109cfu/g.By measuring the amount of spores of the solid fermentation product of Streptomyces roseflavus Men-myco-93-63 with corn grits as the substrate,the storage stability of the solid fermentation product was tested.The solid fermentation product was stored according to the cold storage and heat storage test temperature of chemical pesticides.It was found that the spores after storage at 54℃ for 7 d and 14 d were 90.23%and 76.79%of the initial spores respectively,showing a certain decrease.The amount of spores stored at-20℃ for 7 d and 14 d was 93.84%and 93.49%of the initial spores respectively,exhibiting a slight decrease.These indicated that the solid fermentation products had certain stability under these conditions.The spore volumes were 3.83×108cfu/g 3.53×108cfu/g,2.80×108cfu/g,2.92×108cfu/g,2.03×108cfu/g,respectively,after stored at room temperature for 1,2,4,6,and 15 months,which were 94.49%,85.25%,67.56%,70.51%,49.06%of initial spore volume which was 4.14×108cfu/g.The spore volumes were 8.89×108cfu/g,8.77×108cfu/g,8.12×108cfu/g,8.30×108cfu/g,6.82×108cfu/g respectively,after stored at room temperature with vacuum packaging for 1,2,4,6,and 15 months which were 92.60%,91.35%,84.58%,86.77%,71.04%of the initial spore volume which was 9.60×10cfu/g.These results indicated that the amount of spores stored at room temperature without vacuum packaging decreased greatly compared to that of vacuum-packaged.Therefore,Vacuum packaging could be used as a long-term storage method for this solid fermentation product.The solid fermentation product of Streptomyces roseflavus Men-myco-93-63 with corn grits as a substrate was used to control root knot nematode disease.The greenhouse pot experiment showed that it had a certain control effect on root-knot nematode disease without any harmness to the tested plants.Among them,10 g/plant has the best control effect with the value of 30.99%,followed by 7.5 g/plant and mixture of solid fermentation product and soil with 1:50.In the field test of watermelon root-knot nematode disease in the greenhouse of Panggezhuang,Daxing,Beijing,the control effects of the first and second harvest were 34.92%and 26.67%,respectively.The test of individual fruit weight,center and edge sugar content found that the application of the solid fermentation product had no effect on the sugar content of watermelon,but increased the single weight compared with the control.In the field efficacy test of cowpea root knot nematode disease,the control effect of the solid fermentation product on root knot nematode disease was 21.81%.During the harvest period,it was found that the treatment with solid fermented product had a significant increase in yield,which was 21.92%higher than the control.