Enzyme productivity increases with increasing biomass concentration. The biomass concentration of T. reesei is increased by supplementing soluble sugars such as glucose or xylose along with insoluble lignocellulosic material. Mohagheghi et al. (1990) reported that the mixture of xylose and cellulose (30:30 g/l) was effective in reducing the lag phase of cellulolytic enzyme production to 6.25 days and resulted in 122 IFPU/l-h productivity. In addition, the same enzyme productivity was observed with pure cellulose, but over 8 days. At the same time, the enzyme titer was reduced by 27% for a mixture of xylose and cellulose compared to pure cellulose (Mohagheghi et al. 1990).