The Combined Cultivation of Feruloyl Esterase-Producing Strains with CMCase and Xylanase-Producing Strains Increases the Release of Ferulic Acid

Abstract

Feruloyl esterase (FAE)-producing micro-organisms to obtain ferulic acid (FA) from natural substrates have good industrial prospects, and the synergistic effect of multiple bacteria can better improve the yield of FA. In this study, on the premise of the synergistic effect of FAE, hemicellulose, and cellulase, the key strain Klebsiella oxytoca Z28 with FAE was combined with CMCase and Xylanase-producing strains to produce FA. The combination of strains with higher FA production are Klebsiella oxytoca Z28, Klebsiella pneumoniae JZE, Bacillus velezensis G1, and their FA production can reach 109.67 μg/g, which is 15% higher than that of single bacteria. To explore the effects of temperature, Ph, inoculum amount, distillers grains concentration and fermentation time on the FAE activity of the combination of strains in the fermentation process, and determined that temperature, Ph, and fermentation time were the main influencing factors and optimized through orthogonal design. The optimized fermentation conditions are 34 °C, Ph 8.0, and fermentation days for 6 days, the FAE activity can reach 270.78 U/L, and the FA yield of the combined strain is 324.50 μg/g, which is 200% higher than that of single-strain fermentation.