Studies On The Screening And Function Of Antagonistic Endophytic Bacteria Against Chinese Cabbage Root Rot

Chinese Cabbage Soft Rot is an epidemic disease in the world,which caused by Erwinia carotovora.It is one of the three biggst important plant diseases of Chinese Cabbage,It has the serious influence to our country vegetables quality and the vegetable farmers income.But it has not yet been inhibited effectively. So it is significant to find one kind of effective biocontrolled bacteria strain to inhibit the disease.About 400 hundred endophytic bacterial strains were isolated in health Chinese Cabbagge from Zhuzhou,Wang cheng, Ningxiang, Langli region in Hunan.Two endophytic bcterial strains were isolated from soybean.By identifying,seven endophytic strain hadantagonistic action to Chinese Cabbage Soft Rot.According to the tomorphological,physiological and biochemical characteries,strain B-401 and B-208 belong to Bacillus spp..The two strains manifested good effect in the greenhouse test.which their results showed that the two strains had strong inhibitive effect.The inhibitive efficacy was 65% respectivelyThe fermentation conditions were studied in order to enable the two strains to be used for industred product,the influence of pH,time,Temperature on bacterial growth and production of antibacteria substance was examined.The strain 401 and 208 best raised time for 48~60h, the optimum temperature is 30~32℃, and initial optimum pH of liquid culture broth for bacterial growth and antibacteria production was 7.5~ 8.0.The result indicated that antibacterial filtrated supernatant fluid of two strains had a strong resistance against the pathogen. The sensitivity of filtrated supernatant fluid of culture were determined to ultraviolet light and heat for standing. It is found the ultraviolet light made great harm to the fluid, the filtrated supernatant fluid of culture of B-401 and the B-208 maintains high antiactiveness under 100℃ temperature.