Improvement of fermentation quality and cellulose degradation in Caragana korshinskii silage by supplementation with an Aspergillus oryzae wheat bran culture overexpressing cellulase

This study aimed to evaluate the use of fermented cultures from A. oryzae strains overexpressing cellulase genes as additives in C. korshinskii silage. The genes celA and celB were overexpressed in A. oryzae, yielding four transformants. These transformants exhibited higher cellulase activity than the wild type. The CelA enzyme was purified and characterized, exhibiting optimal activity at 50°C and pH 4.0. During solid-state fermentation using wheat bran, transformants 2A and 2B produced substantial amounts of enzymes and mycoprotein. Adding this AOC to silage provided substrate for lactic acid bacteria, boosting lactic acid and lowering pH. It also increased crude protein content while reducing the fiber components, including NDF, ADF, HC and CEL. These results provide a feasible approach for enhancing plant fiber utilization through microbial engineering technology.