Optimization Of Fermentation Conditions Of Bacillus Subtilis BH-8 And The Control Of It Against Tomato Gray Mould

Tomato grey mould,caused by Botrytis cinerea Pers.,invaded not only tomato,but also other plants,which inflicted serious production losses.The control measures in production mainly rely on chemical control at present,but long-term use of chemical agent led some problems such as vestigital and fungicide resistance and so on.A strain called BH-8 was screened through soil plate separation method,which has an antagonistic effect to tomato grey mould.Then optimizing fermentation conditions,testing the stability of fermentation filtrate and control efficiency of fermentation filtrate are implementing by leaves in vitro and greenhouse pot experiment.The results were as follows:1.BH-8 was initially identified as Bacillus subtilis through analyzing 16 S rDNA sequence.2.Optimized fermentation conditions and liquid fermentation medium,and the results of the best bed fermentation showed that 3% inoculation volume,initial pH 7.0,amount of load 50-75 mL,bed rotation speed 180r/min,reaction temperature 28?,fermenting for 5 days.The optimal medium ingredients were corn flour 2%,beef extract 1.5% and KH2PO4 0.15%.3.The test of stability results showed that BH-8 fermentation filtrate has a wide pH range at 3.0-10.0,strong ultraviolet and temperature stability.4.The control efficiency of BH-8 fermentation filtrate was 81.01% in vitro.In the potting,control efficiency of BH-8 fermentation solution and fermentation filtrate was 90.01% and 89.84%.Both of them had good control efficiency to tomato grey mould,which is equal to chemical agents.And in the potting,control efficiency of BH-8 bacterium suspension was 64.49%,indicating that both of thallus and fermentation had control efficiency to tomato grey mould.