The Analysis Of Active Substances Of Anti-bacteria JK-2 Crude Toxin And The Induced Resistance To The Banana Wilt Disease

The antagonistic bacterium JK-2 (Brevibacillus brevis JK-2) was identified by the fatty acids, wich was isolated from soil by ourselves, having the abilities inhibiting on Fusarium oxysporum and Ralstonia solanacearum. The growth curve of antagonistic bacterium, Brevibacillus brevis JK-2, was determined for the crude toxins extraction. The results showed that it was better for F. oxysporum f. sp. cubense to cultivate 36 h under the conditions of 30℃, 170 r/minn to get the crude toxins for testing. The crude toxins had a certain thermal stability of antibacterial activity, with 1h water bathing at different temperatures, It was measured higher antibacterial activity at 30℃. Although the optimum pH of the crude toxins was 7.0,At pH 3.0 and pH 11.0, It could keep a high antibacterial activity, The crude toxins was nonsensitive to protease K, light and ultraviolet irradiation.The crude toxin of antagonistic bacterium JK-2 precipitated by sulfuric acid was lost its basic activity. Experimental results by 80% ethanol precipitated crude toxin show that: supernatant and precipitation have antibacterial activity on Fusarium oxysporum f. sp. cubense, but at 100℃after 0.5 h in a water bath, sedimentation lost its activity. The supernatant of the activity has not changed. This shows that the crude toxin contain two active substances at least. The use of SDS-PAGE, HPLC and other means for dealing broth were studied. Exopolysaccharide of antagonistic bacterium JK-2 by Column Chromatography, Infrared Spectroscopy and other methods to determine their identification,With Sephacryl S-200 and Superdex-75 gelation column, all appeared obviously single peak, Infrared Spectroscopy show it was composed of carboxylic acids, pyrane monomer, but not peroxyacetyl group.The infection characteristics of GFP-JK-2 and the disease-resistant of banana's related enzyme activity was studied. The results showed that: In the conditions of 30℃, 12 h dark and 12 h light, GFP-JK-2 could not be infected it. the activity of PPO and POD was significantly higher than the CK, and delayed the time of PPO's maximum activity. SOD's activity did not change in the roots. The SOD's activity of stems and leaves were lower than CK. MDA content increased than CK, and MDA in the body content of plant tissue: leaves> roots> stems.Different treatments was set up in order to study induced resistance, After inoculated the bacterium, SOD's, POD's and PPO,s activity and MDA content were determined. The results showed that: The treatment wich was inoculated GFP-JK-2 made PPO, POD activity was significantly higher than other treatments, its activity was induced after 6d, 4d respectively but pathogens were the first impact of POD, The SOD activity of plant roots of all the treatments compared with CK no significant change but the SOD activity of leaves markedly improved wich was only inoculated Fusarium oxysporum f. sp. cubense. Pathogenic bacteria vaccination and antagonistic bacterium JK-2 made plants MDA content increase in various degrees, but two strains inoculated at the same time wich made smaller changes than others. Therefore, After treatment, the pros and cons of the plant to be further studied.