Brewers’ spent grain (BSG) is the most abundant by-product of brewing. Due to its microbiological instability and high perishability, fresh BSG is currently disposed of as low-cost cattle feed. However, BSG is an appealing source of nutrients to obtain products with high added value through microbial-based transformation. As such, BSG could become a potential source of income for the brewery itself. While recent studies have covered the relevance of BSG chemical composition in detail, this review aims to underline the importance of microorganisms from the stabilization/contamination of fresh BSG to its biotechnological exploitation. Indeed, the evaluation of BSG-associated microorganisms, which include yeast, fungi, and bacteria, can allow their safe use and the best methods for their exploitation. This bibliographical examination is particularly focused on the role of microorganisms in BSG exploitation to (1) produce enzymes and metabolites of industrial interest, (2) supplement human and animal diets, and (3) improve soil fertility. Emerging safety issues in the use of BSG as a food and feed additive is also considered, particularly considering the presence of mycotoxins.

Key points

• Microorganisms are used to enhance brewers’ spent grain nutritional value.

• Knowledge of brewers’ spent grain microbiota allows the reduction of health risks.

啤酒厂的废谷物（BSG）是酿造最丰富的副产品。由于其微生物的不稳定性和高易腐性，新鲜的BSG目前作为低成本的牛饲料被处理掉。但是，BSG是吸引人的营养来源，可通过基于微生物的转化来获得具有高附加值的产品。因此，BSG可能成为啤酒厂本身的潜在收入来源。虽然最近的研究已详细涵盖了BSG化学成分的相关性，但本综述旨在强调微生物的重要性，包括新鲜BSG的稳定/污染对其生物技术的利用。实际上，对与BSG相关的微生物（包括酵母，真菌和细菌）的评估可以使其安全使用和最佳的利用方法。这项书目检查特别着重于微生物在BSG开发中的作用（1）产生工业上感兴趣的酶和代谢产物；（2）补充人和动物的饮食；（3）改善土壤肥力。还考虑了在使用BSG作为食品和饲料添加剂时出现的新安全性问题，特别是考虑到真菌毒素的存在。

关键点

•微生物用于提高啤酒酿造者的谷物营养价值。

•了解啤酒酿造者的废粮微生物群可以降低健康风险。