CHAPTER 16: Cloning, Mutation and Over-Expression of Lignocellulase Genes

Enzymatic degradation of lignocellulose is recognized as the hydrolysis method with the greatest potential for improvement and cost reduction for conversion processes. Methods for biomass pretreatment have been developed to increase the reactivity and digestibility of lignocellulosic materials; these have made the enzymatic hydrolysis of lignocellulose possible. However, the cost of enzymes for converting lignocellulose to fermentable sugars remains a major impediment to the development of an economical biofuel industry. The main factors contributing to the cost of enzymes are enzyme properties including specific activity, stability, susceptibility to inhibitors, and the efficiencies of industrial-scale enzyme production. Molecular biotechnology is now a crucial technique for finding novel enzymes, improving enzyme properties, and increasing enzyme yields. This chapter focuses on cloning lignocellulase genes from animal guts and gut microbiota, gene-expression systems for the production of recombinant lignocellulases, improving the expression levels and properties of recombinant enzymes via mutagenesis and the cutting-edge technologies developed in recent years.