关键词: 灰葡萄孢, 解淀粉芽胞杆菌, 发酵条件优化, 生物防治

Abstract: The bacterial strain TD-7, which was isolated from the rhizoplane soil of the perennial plant peppermint by plate dilution method, had a good inhibitory effect on the tomato grey mould Botrytis cinerea. The bacterium was identified as Bacillus amyloliquefaciens based on morphological features and sequence analysis of 16S rDNA and ITS. We investigated the inhibition mechanism, optimal fermentation condition, optimal fermentation medium composition and control effect of the TD-7 fermentation filtrate. The results show that the fermentation filtrate had a strong inhibition effect on the spore germination of B. cinerea with the inhibition rate of the mycelium growth over 95%. In vitro, strain TD-7 can secrete chitinase, cellulase and protease, while the activity of beta-1,3-glucanase was undetectable. The optimal fermentation conditions for producing antimicrobial substance were 250 mL flask, volume ratio of seed liquid 3%, fermentation medium 50-75 mL, initial pH 8.0, temperature 32-36℃, rotation speed 200 r/min and fermentation time 5 d. Orthogonal test demonstrated that the optimal medium was composed of 3.0% corn meal, 1.5% peptone and 0.05% KH₂PO₄. By optimizing fermentation conditions of shake cultivation and components of fermentation medium, the inhibitory activity of TD-7 fermentation filtrate was increased by 26.39%. The TD-7 fermentation broth had remarkable control efficacies on the tomato grey mould in the pot and greenhouse experiment as 80.61% and 87.70%, respectively. The stability experiment of the TD-7 fermentation filtrate shows that the active substance had a broad adaption range to pH value (pH 4.0-9.0), and was stable under high temperatures and UV-treatment. This suggests that the strain TD-7 of B. amyloliquefaciens is promising to be developed into a biocontrol formulation for controlling the tomato grey mould.

Key words: Botrytis cinerea, Bacillus amyloliquefaciens, fermentation condition optimization, biocontrol