Comparison of the impacts of cellulase and laccase on fermentation quality, bacterial composition and in vitro degradability of anaerobic cofermentation derived from Sudan grass with mulberry under Lactobacillus plantarum and different lignocelluloly

Abstract The objective of this study was to evaluate the synergistic and differential effects of inoculation with lignocellulolytic enzymes and ferulic acid esterase (FAE)-producing Lactobacillus plantarum on the fermentation characteristics, bacterial community and in vitro degradability of Sudan grass and mulberry and their mixed silage. Sudan grass and mulberry were mixed at mass ratios of 10:0 (S), 7:3 (S–7), 5:5 (S–5), 3:7 (S–3) and 0:10 (M). With the following treatments were applied: no treatment (CK); L. plantarum alone (LP); L. plantarum , cellulase and xylanase combined (LCX); or L. plantarum , xylanase and laccase combined (LXL). Compared with the control, all the additives (especially the bacterium–enzyme combinations) increased the lactic acid (LA) concentration, water-soluble carbohydrate (WSC) content and relative abundance of Lactobacillus ; decreased the pH, ammonia–nitrogen (AN) concentration, coliform count and relative abundance of undesirable bacteria such as Enterobacter ; and facilitated lignocellulosic degradation. LCX was more effective in degrading neutral detergent fiber (aNDF) and acid detergent fiber (ADF), decreased the pH, increased the WSC content and simplified the structure of the bacterial network, whereas LXL was better in degrading lignin and enhanced in vitro fermentation efficiency. In addition, LXL improved the silage quality by increasing the acetic acid (AA) concentration and relative abundance of Lactobacillus buchneri . Compared with ensiling alone, mixed ensiling balanced the nutrient composition, reduced the butyric acid (BA) concentration and relative abundance of Enterobacter , increased the relative abundance of Lactobacillus , increased the bacterial network positive correlation ratio and promoted in vitro dry matter (DM) digestibility. Overall, mixed ensiling and bacterium–enzyme inoculation improved fermentation quality. Graphical Abstract