Fig. 4From: Metabolic engineering of Escherichia coli for efficient biosynthesis of fluorescent phycobiliproteinDirected evolution of CpcS. a The expression of wild-type CpcS resulted in pink clones and a null mutation in CpcS resulted in white clones, while the clones expressing CpcS mutant with enhanced activities showed red or purple coloration, which could be easily distinguished from the library. b Cell pellets of the wild type and five selected mutantsBack to article page