Optimization of Sporulation Parameters for Aerobic Composting Bacillus subtilis GX2 Strains

Abstract:

Bacillus subtilis is an important microbial agent during the aerobic composting. To reduce the production cost and improve the quality and applicability of bacteria, the spore production process of Bacillus subtilis was studied. Firstly, the culture medium and environmental conditions of Bacillus subtilis GX2 were optimized using shaking flasks. Cell concentration was further increased by a batch feed optimization method in a 3 L fermenter. Finally, single-factor and orthogonal experiments were applied to optimize the spore-forming process. The results showed that the number of viable cells and spores in the fermentation broth reached 1.57×10¹⁰ CFU/mL and 1.32×10¹⁰CFU/mL, respectively, and the spore rate was 84.1% when rotating under 150 r/min at pH 6.8 and 50 ℃. To conclude, the optimization of fermentation and spore production for Bacillus subtilis GX2 effectively increased the number of viable cells and spores in the fermentation broth, and reduced the cost of microbial agents. This work provides guidance for Bacillus subtilis culture and lays the foundation for subsequent industrial production and application of aerobic composting.