Regulatory effects of molasses on microbial community and amino acid profiles during alfalfa high-temperature fermentation

The harvest period of alfalfa is highly concentrated in midsummer. To clarify the impact of high temperature on the fermentation process and the regulatory effect of fermentation methods on microbial community structure and amino acid metabolism, this experiment designed treatments involving fermenting alfalfa with molasses additives for 60 days under two temperature conditions: 35 °C and ambient temperature. High-temperature molasses fermentation promotes thermotolerant bacteria proliferation. Treated alfalfa's bacterial community differs sharply from fresh samples, with the most obvious changes at high temperatures. High temperature lowers <i>Weissella</i>'s relative abundance, but it still reproduces in molasses-rich environments. It restricts glutamine-glutamic acid interconversion, reducing most amino acids. Molasses reshapes microbiota, regulates amino acids, and better inhibits degradation at high temperatures. In conclusion, temperature alters fermented alfalfa's microbial structure and amino acid expression; molasses aids amino acid retention under high heat.