Bacillus Thuringiensis Nu-1, Nu-2 Virulence And Protection Of Research

The main topic of the paper is the increase and protection of toxicity of two Strains , NU-1 and NU-2, of Bacillus thuringiensis.The culture of strains and seeds of NU-1, NU-2 was researched to screen out the suitable culture condition. The orthogonal experiment was tested to select the best fermentation medium. The crystal protein was purified and its density was measured. Result showed: when the No1 seed medium, the inoculation of 4%, 72 hours' culture of strain and 7 hours' culture of seed were used, the fermentation of NU-1 in No2 and No10 fermentation media were highest and fermentation of NU-2 in No.4 fermentation medium get the best effect. In No.2 fermentation medium of NU-1, the quantum reached 85.8 X 108/ml, and the density of crystal protein was 6.320mg/ml after 40 hours. The result of NU-1 in No. 10 fermentation medium was similar to No.2. In No4 fermentation media of NU-2, the quantum reached 78.0X108/ml, and the density of crystal protein was 6.085mg/ml after 42 hours. The curves of growth and pH were tested.Chemical additives were used to enhance the activity of Bt. The results indicated that No.l and No.2 additives both increased the quantum of strains and shortened the time of fermentation.Experiments were designed to treat Bt with different preservations. Results showed that No. 1 and No.2 restrained strongly the sprouting of spores and the growth ofBt within 0-96 hours.The Ultraviolet-mediated impairment and protection of NU-1 and NU-2 were studied by the means of SDS-PAGE, test of enzyme activities and SEM. Results showed: the morphology and surface of PC were damaged by UV rays; the activities of enzymes and the solubility of parasporal crystal were almost lost after 24h radiation. Bt suspension with 0.5% amaranth exhibited the good solubility and retained most activities of enzymes after UV radiation. It was proved that Bt suspension with amaranth showed strong anti-ultraviolet effect.