Using soybean and corn processing co-products in different fermentation systems

Abstract

Two agro-industrial co-products, soybean cotyledon fiber and distiller’s dried grains with solubles (DDGS), were used as the substrates to evaluate the effect of co-culturing three different fungi, Aspergillus oryzae, Trichoderma reesei, and Phanerochaete chrysosporium, on enzyme production by solid-state fermentation (SSF). When soybean fiber was used as the substrate, maximum xylanase activity of 757.4 IU/ g and cellulase activity of 3.2 IU/ g were achieved with the inoculation and incubation of T. reesei and P. chrysosporium for 36 h, followed by A. oryzae for additional 108 h. This inoculation scheme also resulted in the highest xylanase activity of 399.2 IU/g compared to other fungi combinations in the SSF of DDGS. A large scale SSF by this fungi combination produced fermented products that had xylanase and cellulase activity of 35.9-57.0 and 0.4-1.2 IU/g, respectively. These products also had 3.5-15.1% lower fiber and 1.3-4.2% higher protein contents, suggesting a potential feed quality improvement.