Exploring the fermentation quality, bacterial community and metabolites of alfalfa ensiled with mugwort residues and Lactiplantibacillus pentosus

Abstract

Abstract Background The inefficient utilization of plant residues leads to serious environmental pollution and loss of plant nutrition. Nevertheless, the herbal residues including valuable mugwort have been rarely explored. Ensiling has been considered as a promising technique to reuse plant residues. Thus, this study investigated the effect of mugwort residues (M) and Lactiplantibacillus pentosus (LAB) on the fermentation quality, bacterial diversity, and metabolites of alfalfa silage after 60 days of ensiling. Results The results showed that compared with control, adding LAB, M and their combination significantly decreased pH (P < 0.05). Among all treatments, LAB + M had the lowest pH, butyric acid and ammonia nitrogen (NH3-N) concentrations (P < 0.05). Besides, lactic acid concentration of LAB + M treatment was increased nearly by 3 times compared with control. A shift on the bacterial profile was clearly observed, of which Lactiplantibacillus pentosus abundance increased to beyond 90% of total bacteria in LAB + M and all additives decreased Enterobacter hormaechei abundance than control (P < 0.05). Meanwhile, metabolite analysis indicated that mugwort residues addition enhanced the metabolites of apiin and apigenin 8-C-[xylosyl-(1- > 2)-galactoside] relevant to flavonoids (P < 0.05). Conclusion The addition of mugwort residues combined with Lactiplantibacillus pentosus significantly improved fermentation quality with the high relative abundance of Lactiplantibacillus pentosus. Moreover, mugwort residues addition could contribute to the upregulation of specific metabolites such as flavonoids, which would provide a new insight for facilitating fermentation with herbal residues. Graphical Abstract