Study On Antagonistic Mechanism Of Antagonistic Bacterium Strains B₁ And B₅ For Grape Botrytis Cinerea And Field Control Efficiency

The antagonistic bacterium strains B1 and B5 isolated from microflora of grape inhibite Grape Botrytis cinerea strongly. The strain B5 belongs to Bacillus sp. while the strain B1 isn't still identified. We have tested the bacteriostatic effects, fermentation conditions, bacteriostatic protein activity and characteristics of the strains B1 and B5, and field control efficiency of antagonists bacterium mixed with pesticide. We get the main conclusions:bacteriostatic effects of antagonistic bacterium strains B1 and B5According to test the bacteriostatic effects, acting mechanism and antimicrobial spectrum of the strains, the results showed that strains B1 and B5 with Botrytis cinerea together for 5d, there shows the bacteriostatic belt wide 6.9～9.67mm on the culture plate, the inhibition maintained 10d later. Prefiltration fermentation of the strains B1 and B5 can inhibit conidia germination of the pathogen significantly, with inhibitive rate ranging from 97.51% to 98.12%. The mechanism of the strains B1,B5 is to induce hyphae deformity, bioplasm concentrate, conidia germination inhibition and distort germ tubes of conidia. The result indicates the strains B1,B5 also have broad antifungal spectrum which can at least inhibit the hyphae growth of 10 pathogens at the rate of 50%.fermentation conditions of antagonistic bacterium strains B1 and B5In order to improve the number of bacterium and antibacterial activity of the strains B1 and B5, the fermentation medium component and conditions have be studied on the shaking table .The result indicates the optimal carbon and nitrogen source of the strain B1 are lactobiose and ammonium nitrate separately while they are glucose and peptone separately in the strain B5.The optimal culture conditions of the strain B1 are that temperature is 28-33℃, culture time is 36-48h, initial pH is 6.0, fluid volume is 50-250ml. The strain B5 is the same to the strain B1 except that the initial pH is 7.0.bacteriostatic protein activity and characteristics of the strains B1 and B5The bacteriostatic efficiency is optimal that protein crude extract salted out from zymotic fluid of the strains B1 and B5 through 70%-80% ammonium sulphate on the growth of Grape Botrytis cinerea. The bacteriostatic belt wide is 21.5 and 22.4mm separately. Bacteriostatic protein of the strains B1 and B5 are steady at high temperature and their activity are constant on the whole when heated at 80℃. Meanwhile they are steady relatively for prolease K. The bacteriostatic protein shows high antibiotic activity under pH 5-10 while the bacteriostatic effect is optimal under neutrality condition. The effieciency is better under alkaline condition compared with acidic condition. Bacteriostatic protein of the strains B1 and B5 have the storage property, and their activity are constant when stored at normal temperature for 30d.field control efficiency of antagonists bacterium mixed with pesticide0.1mg/ml Sanmate(25% wettable powder) screened out by the experiment have no bacteriostatic effects on the antagonistic bacterium strains B1 and B5. There is synergized action if they mixed with the strains B1 and B5. The results indicate that when 0.1mg/ml Sanmate mixed with the strains B1 and B5, the control efficiency on Grape Botrytis cinerea is 87.41% and 88.50% separately in the room while the efficiency also can reach 80% in the trellis greenhouse. The control efficiency is 81.38% when 0.1mg/ml Sanmate mixed with the strains B5 while the disease rate is only 6%. It is better than the efficiency using antagonistic bacterium and Sanmate only.