Study On The Fermentation Of Bacillus Amyloliquefaciens WH1 And Its Biocontrol Effect On Colletotrichum Gloeosporioides And Tumor

The research includes two parts:one is optimization of fermentation medium of Bacillus amyloliquefaciens WH1 and its control effect towards Colletotrichum gloeosporioides;the other is study of the antitumor effect of surfactin produced by WH1.1. Lipopeptide produced by Bacillus plays an anti-fungal role by act on the cell membrane to elicit pores on it or induce apoptosis. B. amyloliquefaciens WH1 isolated from the root of rice was found to produce cyclic lipopeptide which is a broad spectrum antibiotics with an effect of being against fungi. In this study, the WH1 fermentation broth was detected with the activity to deform the mycelium of C.gloeosporioides, and the 50 fold diluted fermentation broth still had a significant control effect on Camellia oleifera Abel leaves in vitro.Take the WH1 as a dedicated biocontrol agent for C.gloeosporioides, its fermentation condition was optimized by Plackett-Burman design, One-factor experimental design and Taguchi array design. The result of Plackett-Burman design shows, among the medium components screened, soybean meal, NH4NO3, Na2HPO4 and culture temperature significantly affect the yield of lipopeptide. The main factor optimization was conducted by One-factor experimental design, and finally the highest yields medium composition obtained through Taguchi array design, Medium cost and other factors into account, the optimal medium composition for lipopeptide production was soybean meal 12 g/L, NH4NO32 g/L, Na2HPO42 g/L, starch 15 g/L.The fermentation in 3 L,20 L and 500 L fermentor was scaled up successfully. Ten fold diluted fermentation broth of fermentation in 500 L fermentor have 50.8% inhibitory rate on C.gloeosporioides, and still reserved 86.2% inhibitory rate on fungus after spray drying. The control effect test in nursery showed the inhibition of WH1 powder on C.gloeosporioides was significantly higher than that of commonly used chemicals. 2. Lipopeptide surfactin has been reported to have a strong anti-tumor activity. The research proved that it could inhibit tumor in vitro, but having a strong hemolytic activity. The inhibitory effect of lipopeptide on ascites tumor and solid tumor was studied by gavage and intraperitoneal injection, the result showed that the gavage and intraperitoneal injection of lipopeptide could not reduce the death caused by ascites tumor or slow down the growth of solid tumor. There is no effect to cure cancer simply by lipopeptide.