The study evaluated the impact of fermentation with Bacillus sp. on the nutritional quality of soybean meal (SBM) and the changes of bacterial community structure during fermentation. High protease-producing strains were screened to degrade SBM macromolecular protein and anti-nutritional factors (ANFs). Unsterilized SBM then underwent an anaerobic solid-state fermentation method to evaluate the effects of fermentation. Results showed that for the nine high-producing protease strains that were screened, acid-soluble protein (ASP) contents in fermented SBM increased, with the highest value found to be 13.48%, which was fermented using strain N-11. N-11 was identified as Bacillus subtilis. N-11 fermentation reduced ANFs such as glycinin and β-conglycinin by 82.38 and 88.32%, respectively. During N-11 fermentation, the bacterial richness and diversity in SBM increased but not significantly. The high-yield protease strain B. subtilis N-11 selected in this experiment improved the nutritional quality of SBM through fermentation, and it can be used for industrial large-scale production.
Keywords: Bacillus; anaerobic solid-state fermentation; anti-nutritional factor; bacterial community structure; soybean meal.
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