Cellulases: Structure, Function, and Applications, Chapter 8

The cellulosic biomass-to-alcohol bioconversion process must become more economical before industry can commercialize this technology on a large scale. Recent advances in the production of fungal cellulase preparations have stimulated interest in enzyme-based biomass conversion processes. The promise of highly efficient conversion coupled to a 'green' technology is now universally appealing. Ingeneral, hydrokytic enzymes offer depolymerization of naturally occurring polymers in high yield, with few or no by-product disposal problems, unlike acid-based processes. Also, cellulase biochemistry has now reached an enabling phase of development, where combined efforts in biochemistry and molecular biology can deliver engineered cellulase systems for industrial application. Now that manyfactors governing cellulase component action on crystalline cellulose; i.e. enzyme synergism, specific activity, and the thermodynamics of enzyme binding and release, have been discovered, the use of advanced concepts to design engineerecd recombinant cellulase systems, such as enzyme component selection and site-directed mutagenesis, is at hand. To be commercially viable, such systems mustproduce highly active cellulases with specific activities, gravimetric yield, and production cost consistent with current fungal preparations. Once these goals are reached, the ability to tune recombinant systems should permit access to new feedstocks and markets.