Isolation And Screening Of Antagonistic Bacteria Against Fusarium Proliferatum And Optimization Of Fermentation Conditions

Corn Sheath Rot caused by Fusarium proliferatum is a new disease in maize production in China in recent years. It doesn’t only influences the production of maize seriously, but also harm the health of human and animal by producing Fumonisins. For the prevention and control of Corn Sheath Rot, there is no effective measures now. From the viewpoint of ecology, the antagonistic microorganism is isolated from the soil of maize field to investigate the control method of the disease in this study. In this study, seven bacterial strains, which was isolated from the corn field, showed the inhibitory activity against Fusarium proliferatum. Main results are shown as follows:1. Seven bacterial strains, which was isolated from the corn field, showed the inhibitory activity against Fusarium proliferatum. It is named as YM-6, YM-7, YM-8, YM-10, YM-13, YM-14, YM-15 respectively. Based on the morphological, physiological and biochemical characteristics and 16 S r DNA sequences analysis, the strains YM-6 and YM-7 were identified as Bacillus mojavensis. YM-8, YM-10 and YM-13 were identified as B. amyloliquefaciens. YM-14 was identified as B. subtilis. YM-15 was identified as B. tequilensis.2. By inoculating pathogen spore suspensions and different antagonistic bacteria in the field, the bio-antagonistic effect of antagonistic bacteria against pathogenic fungi of Corn Sheath Rot and Ear Rot was further verificated under the natural conditions. The degree of disease was investigated in stage of milky repeness and the yield of maize was measured after harvest. The results showed that different antagonistic bacteria have certain control effect against the pathogens, and further can save the yield loss of maize caused by pathogen, among which the combination of strain YM-8 and YM-15 had the best effect. Field control effect reached 84.21%3. The fermentation conditions of two strains YM-8 and YM-15 were optimized. The optimal fermentation conditions of YM-8 were sucrose 3.0%,tryptone 3.0%,KH2PO4 0.01%,Ca Cl2 0.01%,primary p H 9.0, inoculation 2%, with a shaking flask volume of 30 m L/250 m L, 120 rpm under 28℃. The optimal fermentation conditions of YM-15 were lactose 1.0%,yeast powder 1.0%,Mg SO4 0.005%,primary p H 7.0, inoculation 2%, with a shaking flask volume of 50 m L/250 m L, 180 rpm under 28℃. After the optimization, the antagonistic activity of the two strains increased by 81.17% and 122.65% respectively.