Cost-efficient sugar-based cellulase production

Enzymes remain a significant operational cost in biochemical biorefining processes. Inexpensive streams of sugar are available at many potential biorefining sites, and these could be an optimal raw material for the on-site production of cellulase enzymes. However, simple sugars do not support cellulase production using conventional cellulase-producing strains, necessitating either process or strain improvements. Here we describe improved glucose-based enzyme production processes enabling industrially relevant cellulase production kinetics. Extracellular protein titers of up to 53 g/L could be reached in under 93 hours, representing an up to 260% improvement in productivity over previously reported results. Glucose-produced enzyme is also shown to perform well on pre-treated corn stover. Using the NREL biorefinery model, enzyme production costs are estimated to be $2,8/kg protein or 6/L produced ethanol. Additionally, we briefly discuss how organic nitrogen could be cycled in enzyme production, and how the described processes could fit into existing and emerging biorefining operations.