Ultrahigh-Throughput FACS-Based Screening for Directed Enzyme Evolution

Directed enzyme evolution has proven to be a powerful tool for improving a range of properties of enzymes through consecutive rounds of diversification and selection. However, its success depends heavily on the efficiency of the screening strategy employed. Fluorescence-activated cell sorting (FACS) has recently emerged as a powerful tool for screening enzyme libraries due to its high sensitively and its abillity to analyze as many as 10(8) mutants per day. Applications of FACS screening have allowed the isolation of enzyme variants with significantly improved activities, altered substrate specificities or even novel functions. This review discusses FACS based screening for enzymatic activity and its potentials application for the directed evolutions of enzymes, ribozymes and catalytic anti-bodies.