Screening and Selection Techniques

In order to efficiently assess mutant libraries encompassing genetic diversification, screening, and/or selection methods are highly required in directed enzyme evolution. High-throughput gas chromatography (GC)- or high-performance liquid chromatography (HPLC)-based screening techniques are routinely employed. Growth-coupled, UV/vis/fluorescence-based, or molecular probe-dependent screening systems can also be chosen based on the signals of enzyme-catalysis. Exerting growth selection pressure on host strains, including antibiotic resistance, auxotrophy, or detoxification, is sometimes possible. This chapter summarizes critically the frequently-used screening and selection systems and documents their applications, particularly when attempting to alter stereo- and/or regio-selectivity.