Institute of Catalysis, CSIC 1 article published in JoVE Biology Directed Evolution Method in Saccharomyces cerevisiae: Mutant Library Creation and Screening Javier Viña-Gonzalez1, David Gonzalez-Perez1, Miguel Alcalde1 1Department of Biocatalysis, Institute of Catalysis, CSIC We present a detailed protocol to construct and screen mutant libraries for directed evolution campaigns in Saccharomyces cerevisiae.