Strategies towards Reduction of Enzyme Cost for Ethanol Production from Cellulosic Biomass

Abstract

To reduce the enzyme cost for commercial production of ethanol from cellulosic biomass, synergistic improvement of the following three technologies are quite important: (1) Low-cost production of enzymes, (2) Optimization of enzyme cocktail for saccharification to obtain more than 500 g of the sugar yield from 1 kg of biomass in 24 hours incubation, and (3) Recovery and reuse of enzymes. In this work, based on the above concept, a method for standardization of evaluation on the efficiency of enzymatic saccharification process has been established. Using this method, performance of a commercial enzyme cocktail for saccharification of ammonia-treated Erianthus ravennae derived cellulosic biomass has been evaluated and the actual strategy towards reduction of the enzyme cost in our process has been focused. In conclusion, to attain less than 10 JPY of the enzyme cost for 1 L of ethanol production from the ammonia treated cellulosic biomass, most feasible combination of the three technologies are elaborated as follows: the enzyme production cost, 1,000 JPY/kg of enzyme as protein base; the enzyme dose by biomass for saccharification, 1/100; the recovery of enzyme as protein base, more than 75 %.