Bacillus Thuringiensis Nu-1, Nu-2 Mixed Fermentation And The Protection Of The Virulence Study

According to the mixed fermentation of Bacillus thuringiensis in 3 kinds of proportions (the inoculation proportion of NU-1,NU-2 being 1:1, 1:3, 3:1, respectively),the results was as follows: for E combination ( the inoculation proportion being 3:l),the synchronous rates of mixed fermentation amount to 83%,the quantum of the strain was 68×10~8/mL on the 41st hour at the end of fermentation , the crystal protein content was 7.334mg/mL, which can be increased by 16.2% and 16.8% respectively comparing with the pure fermentation.Therefore adopted 3:1 as the best inoculation proportion of NU-1 and NU-2.The effects of different factors on protoplast formation of Bacillus thuringiensis strain NU-2 were studied . The best protoplast formation condition was cultivated for 10 hours and activated for another 5 hours, pH7.0, lysozyme dose 0.6mg/ml, 42℃ for 60 minutes.The protoplast of NU-2 was treated by UV and LiCl .The NU-2-16 strain whose fermentation period was accordant to NU-1 was selected.Its crystal protein content was increased by 10.03% comparing with original strain.The mixed fermentation of the mutagen strain NU-1and NU-2-16 showed: the synchronous rates amount to 98%, the quantum of the strain was 72.4×10~8/mL on the 40th hour at the end of fermentation, the crystal protein content was 7.896mg/mL, which can be increased by 7.7% comparing with the mixed fermentation of original strains.Studies on blend nitrogen and C/N of the mixed fermentation about NU-1 and NU-2-16 ,conclusion as follow : fermentation period ahead to 38 hours when soy flour and yeast extract were the blend nitrogen sources ; the strain and the crystal protein content were comparatively high when the ratio of C/N was 1:2.5. The result got the best medium formula (%):soy flour 2.5, yeast extract 2.5,amylum 2.0, CaCO3 0.15, K2 HPO4 0.5 ,MgSO4 0.035.On the condition, the quantum of the strain was 83.6xl08/mLon the 38th hour at the end of fermentation, the crystal protein content was 8.351mg/mL.Studied the different consistency humic acid, Congo red, methyl green, pupa powde as uv-screen on the spore livability ,the result showed: Congo red of 0.05% was the strongest anti-ultravioler effect, and then were methyl green of 0.1%, pupa powde of 0.5% and humic acid of 0.5%. SDS-PAGE electrophoresis showed :the two toxin albumen of 135 and 65 Dalton still exist which produced by the parasporal crystals of Bacillus thuringiensis with Congo red of 0.05%, on the 4th . Congo red was the strongest anti-ultravioler effect which can obviously protect for the parasporal crystals of Bacillus thuringiensis .