An innovative way to treat cash crop wastes: The fermentation characteristics and functional microbial community using different substrates to produce Agricultural Jiaosu.

With the increase of global demand for cash crops, a large of cash crop waste was produced and caused severe environmental issues. To produce Agricultural Jiaosu (AJ) using these wastes is a sustainable waste disposal method. However, the fermentation mechanism, metabolites, and microbial characteristics of AJ fermented with different substrates remain unclear. In this study, the effects of different substrates (fruit and vegetable waste and Chinese herbal medicine waste) on the fermentation characteristics of AJ, including metabolites and microbial community properties, were investigated. The results revealed that AJ fermentation was a process of converting organic matter into organic acids and other metabolites, mainly including hydrolysis, acidogenesis, and maturation stages. At the genus level, Lactobacillus, Acetobacter, Hydrogenibacillus, Halomonas, and Prevotella_1 were the dominant bacteria in the fermentation system. The bacterial diversity of composite substrate AJ was higher than that of single substrate AJ. The organic acids and secondary metabolites concentration and the composition of key microorganisms depended on the substrate type. Furthermore, AJ's potential functional genes were mainly concentrated in cofactors and vitamin, carbohydrate, and amino acid metabolism. The findings of this study indicated that AJ is an innovative eco-friendly technology that can convert cash crop wastes into sustainable eco-products, and that its characteristics depend on the substrate type. Therefore, the substrate used to produce AJ should be carefully selected according to the application field.