Fed-batch high-solids enzymatic saccharification of lignocellulosic substrates with a combination of additives and accessory enzymes

The operation of high-solids enzymatic saccharification at low cellulase loading is required for the commercialization of the current cellulase-mediated lignocellulosic bioethanol. In this study, high-solids (30 %) fed-batch enzymatic saccharification at low cellulase loading (3 FPU/g) was attempted by fed-batch mode with a mixture of additives and accessory enzymes. The saccharification process began with 10 % (w/v) solids content and 6 %, 6 %, and 8 % of substrates were fed at 6, 12, and 24 h to achieve 30 % (w/v) of the total solids content. With the optimization of additives, namely 40 mg/g Tween 80, 30 mg/g tea saponin, 8 mg/g BSA, and 2.4 mg/g xylanase and 0.4 mg/g AA9 as accessory enzymes, the saccharification process released 180 g/L of fermentable sugars with 70 % glucose yield after 72 h. The fed-batch mode along with the mixtures of some additives and accessory enzymes has been found to be a beneficial approach to run a high-solids enzymatic saccharification at low enzyme loading.