Rice is one of the most important food crops in China,but the occurrence of rice diseases has seriously affected the development of rice industry in china.Among them,Fusarium moniliforme in rice can lead to decreasing rice yield and quality.At present,the prevention and control of Fusarium moniliforme in rice is mainly in the chemical agent.However,due to long-term using chemical agent,which results in the resistance of Fusarium moniliforme,contaminates soil and natural environment.Biological control is becoming a hot spot.Therefore,in order to obtaining high biocontrol strains,this study plans that an antagonistic strain against Fusarium moniliforme in rice was selected from the rhizosphere soil of rice.This study separated strains from the rhizosphere soil of rice by dilution coating plate method,and the antagonistic strains were screened by flat confrontation method using the Fusarium moniliforme as the indicator strain.It was identied by morphological,physiological and biochemical characteristics and 16 S rDNA phylogenetic analysis,and detected the effects of its sterile fermentation broth on the growth of Fusarium moniliforme.Also flat confrontation method was used to study the antifungal spectrum and potted experiments was used to explore the biocontrol effect on Fusarium moniliforme in rice.Six strains of antagonistic fungi were isolated,one strain SH15 with strong antagonistic effect on Fusarium moniliforme was identified as Paenibacillus polymyxa.P.Polymyxa is a kind of the plant growth-promoting bacteria with biocontrol effect,producing antibacterial protein,antibiotics and polymyxin,which has been widely used in agricultural production.Sterile fermentation broth of the P.Polymyxa SH15 had significant inhibitory effect on the growth of Fusarium moniliforme,and the antifungal spectrum of the strain SH15 was broad,and it had some antifungal activity against Fusarium moniliforme,Fusarium proliferatum,Fusarium oxysporum,Phytophthora capsici,Verticillium alboatrum,Alternaria cucumerina.Rice pot experiment showed that inoculation of the Paenibacillus polymyxa SH15 could significantly reduce the incidence index of Fusarium moniliforme in rice for the average control effect being as high as 65.68%.Therefore,Paenibacillus polymyxa SH15 has a certain application value in the biological control of Fusarium moniliforme in rice.In order to improve the viable count of Paenibacillus polymyxa SH15,fisrtly the carbon and nitrogen source were optimized by the experiment of single factor,and on the basis of this,the most appropriate amount of carbon and nitrogen source,sodium chloride,MgSO4·7H2O,CaCO3 was optimized by experiment of single factor,getting 3 main influencing factors.Then,the fermentation medium was optimized by Box-Behnken method,obtaining the optimal formula: corn flour 37.20g/L,yeast extract 25.00g/L,NaCl 4.25g/L,MgSO4·7H2O 0.50g/L,CaCO3 1.22g/L through the analysis of response surface method.Under this condition,the number of viable count of Paenibacillus polymyxa SH15 could reach 2.11×10~9cfu/mL,Which was increased by 0.99 times than before optimization.In order to improving the level of solid-state fermentation of paenibacillus polymyxa SH15,making full use of the by-product mushroom bran of mushroom industry,enhancing the value of the resources.In this paper,the mushroom bran was used as the main raw material for solid state fermentation of the Paenibacillus polymyxa SH15,so as to producting microbial fertilizer.The experimentof single factor and response surface method were used for studying of mushroom bran and wheat bran proportion,fermentation time,initial moisture content,effect of adding inorganic salt,fermentation temperature,bottling amount on Paenibacillus polymyxa SH15 growth and spore formation,determining the optimum cultivation conditions,which were mushroom bran 20 g,wheat bran 8g,the initial water content of 60.75%,manganese sulfate 0.50%(w/w),fermentation temperature 33.21℃,fermentation time 144 h,inoculation amount 10%(w/w).Under this condition,the viable count,the number of spores and spore rate of Paenibacillus polymyxa SH15 were 5.02×10~9cfu/g,4.61×10~9cfu/g,91.8%,which were far higher than the national standard GB 20287-2006 of agricultural microbial fertilizer requirements.This shows that mushroom bran can be used as raw materials in solid state fermentation culture of Paenibacillus polymyxa SH15,for producting microbial fertilizer and other agricultural microbial agents.This study can reduce the production-cost of microbial fertilizer,meanwhile,which provide a new of thinking for making full use of mushroom bran resources. |