Two-stage fermentation of corn and soybean meal mixture by Bacillus subtilis and Lactobacillus acidophilus to improve feeding value: optimization, physicochemical property, and microbial community

Microbial treatment can reduce the antinutritional factors and allergenic proteins in corn-soybean meal mixture (CSMM), but the role of the microbial community in hypoallergenicity and digestibility during the fermentation process remains unclear. Therefore, the fermentation strains of Bacillus and LAB were determined, and the compatibility and fermentation process of two-stage solid fermentation composite bacteria were optimized, and the dynamic changes in physicochemical property and microbial community during two-stage fermentation were investigated. Results showed that Bacillus subtilis NCUBSL003 and Lactobacillus acidophilus NCUA065016 were the best fermentation combinations. The optimal fermentation conditions were inoculum 7.14%, solid–liquid ratio of 1:0.88 and fermentation time of 74.30 h. The contents of TI, β-conglycinin and glycinin decreased significantly after fermentation. Besides, TCA-SP, small peptides and FAA increased. Bacillus and Lactobacillus were the main genera. Pathogenic bacteria genera were inhibited effectively. This study suggests the feasibility of two-stage fermentation in improving the nutrient values and safety of the CSMM.