ABSTRACT
Cellulase production is an essential and important step in the biomass-to-ethanol process. This chapter reviews the cellulase production technology with an emphasis on realistic processes in relation to ethanol production. Cellulose is a major structural polysaccharide of plants with high tensile strength and resistance to degradation. Functionally complete cellulase enzyme systems can be produced by diverse microorganisms such as aerobic and anaerobic bacteria, white rot fungi, soft rot fungi, and anaerobic fungi. In cellulase fermentations, enzyme activities are customarily reported in filter paper units (FPU)/mL, and there is a standard International Union of Pure and Applied Chemists (IUPAC) protocol for determining FPU/mL. The carbon/nitrogen (C/N) ratio and the types of carbon and nitrogen sources and their individual concentrations are important parameters in cellulase production. Fed-batch enzyme production is strongly influenced by the feeding rate and final effective substrate concentration.
