As estimated in the
report by Klein-Marcuschamer et al. (2012), the cost of producing
cellulase was much higher than that commonly assumed in the lit-erature. The cost of cellulase (10 FPU/g cellulose) was found to be
$1.13/gal if the conversion of the C6 sugar was 95% efficiency but
not C5 sugars. Also, they pointed out that if the cellulase loading
could be lowered to 5 FPU/g cellulose, the cost contribution of
enzyme would be $0.55/gal. The cellulase loading in the present
study was 7.5 FPU/g cellulose which resulted in a slight higher
enzyme cost than $0.55/gal