Improvement of bioactivity of soybean meal by solid-state fermentation with Bacillus amyloliquefaciens versus Lactobacillus spp. and Saccharomyces cerevisiae

• Bacillus fermentation is optimal for improving soybean meal nutritional value.
• Antioxidative and chelating activity can be improved by solid-state fermentation.
• Bioactive peptide is important for improving fermented soybean meal bioactivity.

To evaluate the impact of fermentation with Bacillus amyloliquefaciens U304 on nutritional quality and bioactivity of soybean meal (SBM), we analyzed the solid-state fermentation process for Bacillus amyloliquefaciens, Lactobacillus spp., and Saccharomyces cerevisiae. B. amyloliquefaciens showed significant improvement in nutritional quality and bioactivity by removing the protein- and carbohydrate-based anti-nutritional factors (ANFs), as well as allergens. The total phenolic content, reducing power, free radical scavenging ability, and Ca2+ chelating ability of SBM, as indicators of the antioxidant activity, increased to 195.8, 201.7% (at 10 mg/mL), 136.6% (at 10 mg/mL), and 122.3%, respectively, after Bacillus fermentation. S. cerevisiae decomposed carbohydrate-based but not protein-based ANFs, and fermentation with this organism produced similar values of the antioxidant markers of unfermented soybean meal, except for the reducing power (160.0% at 10 mg/mL). Lactobacillus spp. was only effective for decreasing the activity of trypsin inhibitors, but not other ANFs, resulting in lower bioactivity of fermented soybean meal. B. amyloliquefaciens U304 can substantially improve both the nutritional quality and bioactivity of SBM.