Nutrition promotion of brewer?s spent grain by symbiotic fermentation adding Bacillus velezensis and Levilactobacillus brevis

作者：Zeng, Jiarui; Sheng, Feibi; Hu, Xi; Huang, Zhenfeng; Tian, Xiaofei; Wu, Zhenqiang^*

来源：Food Bioscience, 2022, 49: 101941.

DOI：10.1016/j.fbio.2022.101941

• Brewer ?s spent grain
• Symbiotic fermentation
• Nutrition promotion
• Bacillus velezensi s
• Levilactobacillus brevis

Brewer's spent grain (BSG) is the main byproduct of the beer industry and is commonly used as a low-value animal feed or food ingredient. This study investigated the role of symbiotic fermentation with Bacillus vele-zensis and Levilactobacillus brevis in improving the nutritional value of BSG. The addition of B. velezensis increased the cell growth of L. brevis by over thirty-fold higher than that in the single-strain system. Simultaneously, cellulase and protease activities were substantially increased, and more soluble sugars were produced. Total amino acid, glutamic acid, and gamma-aminobutyric acid (GABA) levels increased by 52.2%, 155.1%, and 144.1%, respectively. Conversely, lactic acid production decreased. Genetic analysis showed that the glycolysis-related gene pykA , pentose phosphate pathway gene gnd , and GABA-related gene gad were upregulated, while the heterolactin-related gene xpkA was downregulated, explaining that B. velezensis might inhibit heterolactin fermentation while enhancing GABA biosynthesis. This study provides a potential strategy for the high-value utilization of BSG in the food or feed industry.