A Study On The Tobacco Endophyte And The Inhibitive Strains Antagonized Against Ralstonia Solanacearum

Tobacco bacterial wilt is a very important quarantine bacterium on the tobac -co,which has not yet been inhibited effectively .so it is significance to find a bio -controlled bacterial strain to inhibit the disease.Nineteen pathogen were isolated from inflected plant and one hundred sixty endophytic bacterial strains were isolated in health tobacco from Yongzhou , chen zhou,Hengyang and Ningxiang region in the research. By identifying, the pathogen strain 2316 was most strong one on inflecting capability. Thirty-two endophytic strain had antagonistic action to tobacco bacterial wilt. According tomorphologi -cal ,physiological and biochemical characteries ,strain 001,009,011 were identified and the strain 001 belong to Bacillus subtilis .strain 009 and 011 belong to Bacillus brevis. By strain 001,009,011 used as bio-control agent against tobacco bacterial wilt in frield, the results show that the three strains had strong inhibitive effect. The inhibitive efficacy was respectively 82.5%, 100%, 84.5%.The inhibitive strain xiang2-3 and 2-qing-9 have good controlled effect for many years in the field .The fermentation conditions are studied in order to enable the two strains to be used for industry product. The result showed that the optimum culture medium for the strain xiang2-3 is : soybean cake meal 20 %, fish mea13% KH2PO40.8%,CaCO3 3%; the optimum fermentation conditions is : fermentation temperature 28C,fermentation time 24h , inoculum size 4%,dissolved oxygen120ml; The optimum culture medium for the strain 2-qing-9 is : soybean cake meal 25 %, fish mea13% KH2PO4 0.7%,CaCO3 4%; the optimum fermentation conditions is : fermentation temperature 30C .fermentation time 26h ,inoculum size 3%,dissolved oxygen80ml.