To develop B. Subtilis BS501a into a biological fungicide, the mycelium growth inhibition rates of B. Sublitis BS501a fermentation supernatant to 15 kinds of plant pathogenic fungi were tested. The results showed that B. Subtilis BS501a fermentation supernatant had strong inhibiting effect on 10 kinds of them, such as rice blast, and the mycelium growth inhibition rates to them were over 85 % . The green house control efficiency of BS501a fermentation supernatant to rice blast was 63. 8% . The biological safety of B. Subtilis BS501a were tested by feeding freeze-drying fermentation supernatant powder to KM mice whose weight were about 20 g. The LD50 of the freeze-drying fermentation super-natant powder to KM mice were over 500 mg · kg-1. The results showed that the fermentation superna-tant of B. Subtilis BS501a had no toxicity and met the requirement of green biological pesticide. The physical-chemical characters of B. Subtilis BS501a fermentation supernatant were tested. The results showed that the antifungal activity of B. Subtilis BS501a fermentation supernatant was stable when the temperature reached 45 ℃ , and the antifungal metabolites were soluble and had strong antagonistic ac-tivities in Ph 7 ~9 environment. The antifungal activity of B. Subtilis BS501a fermentation supernatant still kept stable after it was kept in (4 500 ±500) 1x for 10 days and even after the digestion of proteinase K. At the tenth generation, the antifungal activity of B. Subtilis strain BS501a fermentation su-pernatant had no significant difference with that of the first one. The results demonstrated that the an-tagonistic metabolites of B. Subtilis BS501a had wide antifungal spectrum, high efficiency, biological safety and stable physical-chemical characters. B. Subtilis BS501a had great potential to develop into a biological fungicide.%为将枯草芽孢杆菌BS501a开发成生防杀菌剂,采用菌丝生长抑制试验,研究其发酵上清液对15种植物病原真菌的抑制效率,发现BS501a发酵上清液对稻瘟病菌等10种病原真菌有很强的抑制作用,菌丝生长抑制率在85％以上.在温室条件下研究其对稻瘟病的防治效果,发现BS501a发酵上清液对稻瘟病的防治效果为63.8％.以体重20 g左右的KM小鼠为试验对象,对BS501a发酵上清冻干粉进行急性经口毒性试验,LD50＞ 500mg· kg-1,说明BS501a发酵上清无毒,符合绿色生物农药要求.研究BS501 a发酵上清理化稳定性和遗传稳定性,发现发酵液低于45℃活性稳定；pH值在7～9环境下可溶,且有较强的拮抗活性；光照度(4500±500)lx照射10 d活性稳定；蛋白酶K作用后,拮抗活性不变；转接10代后拮抗活性稳定.结果表明,枯草芽孢杆菌BS501a拮抗代谢物广谱、高效、安全、性能稳定,BS501a菌株有进一步研发价值.
展开▼
