Screening of Solid State Fermentation Conditions of Waste Stem for Producing Bacillus Thuringiensis

Using waste tobacco stem as raw material, the medium compositions and conditions of solid state fermentation for Bacillus thuringiensis HD-1 growth were optimized by orthogonal design and single factor experiments. The results showed that the optimal medium composition was: tobacco stem 88.13%, dusty yeast 1.17%, peptone 1.17%, ground soybean cake 5.88%, corn flour 2.93%, KH₂PO₄ 0.18%, MgSO₄·7H₂O 0.24%, FeSO₄ 0.12% and MnSO₄ 0.18%. The best culture conditions were: inoculation concentration 6%, initial water content 65%, initial pH of the medium 7.5, under which sporulation stabilized at 9.5×10₁₀ CFU/g. It was feasible to produce Bacillus thuringiensis by solid state fermentation using waste tobacco stem as the main medium．