Emerging and innovative utilisation of herbal medicine residues in anaerobic fermentation of corn straw: Cellulose degradation, fermentation characteristics, and microbial community structure and co-occurrence network

Abstract

To realise efficient utilisation of herbal medicine residues and reduce environmental pollution, the cellulose degradation, fermentation characteristics, and microbial community structure of corn straw silage treated with Astragalus memeranaceus F. (AM), Bupleurum falcatum L. (BF), Acanthopanar gracilistμlus W. (AG), Codonopsis pilosula F. (CPF), Salvia miltiorrhiza B. (SM), Taraxacum mongolicum Hand (TMH), Common Yam R. (CY), Plantago asiatica L. (PA), Saposhnikovia divaricata T. (SD), Poria cocos S. (CP), and Spatholobus suberectus Dunn (SSD) were investigated. In the herbal medicine residue groups, the levels of lactic acid, acetic acid, propionic acid and 2,3-butanediod levels increased to 34.29–45.34 g/kg DM, 34.39–54.28 g/kg DM, 6.21–8.48 g/kg DM and 1.28–1.92 g/kg DM, whereas the levels of ethanol and 1,2-propanediol decreased to 0.37–0.84 g/kg DM and 0.42–1.54 g/kg DM compared to those in the control group. NH₃-N levels decreased to 0.42–1.68 g/kg DM in all herbal medicine residue groups than in the control group, except for SM and SSD groups. Corn straw silage treated with BF and AG had lower acid detergent fibre and neutral detergent fibre contents than the control. The herbal medicine residue groups showed increased abundance of Lactiplantibacillus plantarum and Levilactobacillus brevis, and decreased abundance of Bacillus licheniformis and Bacillus subtilis. In conclusion, investigating the effects of herbal medicine residues on corn straw fermentation highlights their potential applications in practical agricultural settings. Moreover, BF and AG groups had the best effect, which not only degraded cellulose but also improved the fermentation quality of corn straw silage through microbial regulation.