Utilising rice straw to prepare a culture medium for synthesizing lactic acid bacteria biofilms and regulating silage...

To effectively utilize crop by-product resources, we developed a low-cost natural culture medium using rice straw as material, successfully synthesized a lactic acid bacteria (LAB) biofilm conducive to silage, and activated LAB activity to drive the silage fermentation process. Commercial freeze-dried LAB strains FG1 (Lactiplantibacillus plantarum) and TH14 (Lacticaseibacillus casei) and their corresponding culture medium, used for the preparation of silage from orchard grass and timothy grass. The crude protein and mineral content in fresh grass was higher than 14.4 % and 3.0 g/kg based on dry matter (DM), respectively, and formed a microbial biofilm structure and symbiotic network dominated by harmful microorganisms. Compared with the control and other treatments, silage prepared using the FG1 medium exhibited excellent fermentation quality, with pH and ammonia nitrogen content below 3.6 and 0.7 g/kg of fresh weight (FW) (P < 0.05), respectively, while lactic acid content exceeded 1.1 g/kg of FW (P < 0.05). The single LAB biofilm constructed using the FG1 medium developed in this study promoted a rapid shift in the silage biofilm community structure from Gram-negative to Gram-positive bacteria. Ultimately, a biofilm structure dominated by Lactiplantibacillus plantarum was formed. This structure effectively regulated the dynamic symbiotic network of silage fermentation microorganisms, increasing the relative abundance of Lactiplantibacillus plantarum to 35.4 %, significantly driving carbohydrate metabolism and global and overview map metabolic pathways while inhibiting amino acid metabolic pathways. This study achieved low-cost and high-quality silage fermentation by scientifically designing the biofilm structure of microorganisms related to silage fermentation.