Mechanism of improved cellulase production by Trichoderma reesei in water-supply solid-state fermentation

High production cost of cellulases limits its commercial application on lignocellulose. Solid-state fermentation (SSF) has special advantages of water and energy conservation, however, the lack of free water and water loss during fermentation limits its application. In this paper, a constructed water-supply SSF was used to improve carboxymethyl cellulose activity and filter paper activity of 1.7-fold and 2.3-fold by Trichoderma reesei Rut-C30, respectively. The dynamic changes in substrate physical prosperities and water characteristics during fermentation indicated that water supply by superabsorbent polymers could improve substrate utilization. Transcriptome results showed that the cells were more active at the early water-supply SSF, accumulating a lot of energy and precursors for cellulase production. Cellulase activity-related genes were significantly up-regulated, especially the glycoside hydrolase family and major facilitator superfamily. These findings provide a mechanism for SAPs to promote high cellulase activity production in solid-state fermentation.