Application of feruloyl esterase BpFae03105 and xylanase XynAS Co-enzymolysis to produce ferulic acid from wheat bran

Wheat bran, rich in phenolic compounds like ferulic acid (FA), faces limited bioconversion due to its recalcitrant lignocellulosic structure. This study developed a synergistic catalytic system using feruloyl esterase (BpFae03105) and xylanase (XynAS) for efficient conversion into FA and xylo-oligosaccharides (XOS). A multi-stage optimization strategy was employed. First, the effective ranges of eight basic parameters were determined through single-factor experiments. Then, Plackett-Burman design was used to screen for significant factors influencing FA yield, identifying enzymatic hydrolysis temperature, time, and enzyme addition ratio as the most critical. The conditions were further optimized using the Box-Behnken response surface method, resulting in the following optimal conditions: enzymatic hydrolysis temperature of 43 °C, reaction time of 4.2 h, shaker rotational speed of 120 rpm, pH 5.0 phosphate buffer, solid-to-liquid ratio of 1:115 (w/v), enzyme addition ratio (BpFae03105:XynAS) of 1:11.2, BpFae03105 concentration of 8 U/mL, and wheat bran particle size greater than 20 mesh. Under these conditions, the FA yield reached 77.98%, a 2.65-fold increase compared to the unoptimized process. In addition, XOS production achieved a substantial yield of 26.24%, marking a significant breakthrough in co-product generation. The proposed mechanism suggests XynAS degrades xylan, disrupting the lignocellulosic matrix and exposing feruloyl ester groups, thereby enhancing substrate accessibility and BpFae03105 catalytic efficiency. The synergistic enzymatic action overcame limitations of traditional individual enzymes systems, particularly product inhibition, enabling integrated wheat bran valorization. Overall, this study provides a novel, scalable biorefinery approach for high-value utilization of agricultural by-products, offering economic and environmental benefits for sustainable biomass processing.