Nutrient composition, microbial diversity, and functional prediction of Baijiu distiller's grains fermented feed via solid state fermentation at different temperatures.

The utilization of Baijiu distiller's grains (BDGs), commonly used as a feed ingredient, remains limited due to challenges such as elevated levels of anti-nutritional factors (ANFs), high fiber content, and low protein concentration. Microbial fermentation has been recognized as an effective strategy to improve the nutritional quality of feed substrates. However, its efficacy is highly dependent on process parameters such as temperature. Despite its significance, the effect of temperature on the interaction between microbial communities and the physicochemical properties of BDGs during fermentation remains poorly understood. To address this gap, BDGs were fermented using Bacillus subtilis, Candida utilis, and Geotrichum candidum under varying temperatures. Comprehensive physicochemical analyses combined with high-throughput sequencing of microorganisms were performed to investigate the dynamic changes in both fermentation products and microbial kinetics. The results revealed that the optimal fermentation performance was achieved at 34 °C. At this temperature, compared to untreated BDGs, phytic acid, tannin, and crude fiber levels were significantly reduced by 65.18%, 30.69%, and 15.34% respectively, whereas crude protein and amino acid contents increased by 15.5% and 7.13%. Furthermore, temperature was found to play a crucial role in shaping the dynamics of microbial community succession, with Stenotrophomonas, Bacillus, Pseudomonas, Paenibacillus, and Pediococcus identified as key bacterial genera influencing the nutritional composition of BDGs. Temperature variations drive shifts in microbial communities and consequently affect the nutritional quality during fermentation. These findings provide valuable experimental evidence and support the potential of fermented BDGs as a viable protein ingredient substitute in animal feed.