Directed Evolution Tools in Bioproduct and Bioprocess Development

This chapter focuses on the strategies for diversity generation that are applicable to the development of bioproducts and bioprocesses via directed evolution. Microorganisms and the enzymes they hold have been exploited by man for thousands of years, for example, in the production of food products through fermentation. Directed evolution tools have been increasingly used to engineer new or improved enzymes, metabolic pathways, and whole genomes for various bioprocessing applications. In the past decade, numerous molecular biology techniques have been developed to create genetic diversity through random mutagenesis and/or homologous or nonhomologous recombination in the target genes, pathways, and genomes. Coupled with the development of powerful high-throughput screening or selection methods, these evolutionary techniques have been successfully used to solve challenging problems in protein engineering and metabolic engineering. In addition, directed evolution is highly complementary to rational design. Its capability is rapidly growing due to recent advances of structural genomics and computational biology. It seems that the combination of directed evolution and rational design represents the most powerful tool for protein engineering and metabolic engineering.