Growth of S. cerevisiae strains expressing codon-optimized genes of the l-arabinose utilization pathway. Growth of recombinant yeast strains with different combinations of codon-optimized genes and original genes were tested in shake flask cultures at 30°C on YNB medium with 20 g liter−1 l-arabinose as the sole carbon source. ⧫, BWY1-SI; ▵, BWY1-SE; □, BWY1-SK; ▴, BWY1-SEK; ▪, BWY1-4S; ⋄, BWY1-4M.