Production of Cellulolytic Enzymes and Its Techno-economic Analysis in the Context of a Biorefinery

Bioconversion of renewable and abundant lignocellulosic resources to commodity products such as energy, food, feed, and chemicals through microbial/enzymatic intervention is being intensively explored to meet the increasing demand of the growing human population along with environmental safeguards. This renewable biomass, which contains the carbohydrate polymers cellulose and hemicellulose, can be enzymatically hydrolyzed to hexose (mainly glucose) and pentose (mainly xylose) sugars that serve as building blocks for their bioconversion into various industrial products. However, as highlighted in this chapter, enzymatic hydrolysis of lignocelluloses presents a significant bottleneck due to the composition, properties, and cost of the available cellulases. The success of projected biorefinery processes depends to a large extent on the economics of hydrolytic enzyme production. Although both submerged fermentation and solid state fermentation are used for the production of cellulolytic enzymes, the industry prefers to use the former where various process variables can be controlled easily. This chapter describes various process strategies by which cellulases can be produced more economically. These include the use of soluble inducers in cellulase production among others. Finally, techno-economic analysis (TEA) and life cycle analysis (LCA) of cellulase production taking into account the different variables that affect enzyme costs are discussed.