Overexpression of D-Xylose Reductase (xyl1) Gene and Antisense Inhibition of D-Xylulokinase (xyiH) Gene Increase Xylitol Production inTrichoderma reesei

摘要

T. reeseiis an efficient cellulase producer and biomass degrader. To improve xylitol production inTrichoderma reeseistrains by genetic engineering, two approaches were used in this study. First, the presumptive D-xylulokinase gene inT. reesei(xyiH), which has high homology to known fungi D-xylulokinase genes, was silenced by transformation ofT. reeseiQM9414 strain with an antisense construct to create strain S6-2-2. The expression of thexyiHgene in the transformed strain S6-2-2 decreased at the mRNA level, and D-xylulokinase activity decreased after 48 h of incubation. This led to an increase in xylitol production from undetectable levels in wild-typeT. reeseiQM9414 to 8.6 mM in S6-2-2. TheT. reeseiΔxdh is a xylose dehydrogenase knockout strain with increased xylitol production compared to the wild-typeT. reeseiQM9414 (22.8 mM versus undetectable). The copy number of the xylose reductase gene (xyl1) inT. reeseiΔxdh strain was increased by genetic engineering to create a new strain Δ9-5-1. The Δ9-5-1 strain showed a higherxyl1 expression and a higher yield of xylose reductase, and xylitol production was increased from 22.8 mM to 24.8 mM. Two novel strains S6-2-2 and Δ9-5-1 are capable of producing higher yields of xylitol.T. reeseihas great potential in the industrial production of xylitol.