Figure 2. Glucoamylases production by wild type and recombinant S. cerevisiae strains. (A) Hydrolysis of raw starch appears as clear zones around S. cerevisiae colonies secreting functional glucoamylases; strain (a) Y294 (reference), (b) Y294[yASAG] secreting the native GAI, (c) Y294[ySYAG] secreting the codon-optimized sGAI, were grown for 4 d on agar containing raw starch and then stained with iodine solution. (B) Glucoamylase and α-amylase activities of the strains Y294[yASAG] and Y294[ySYAG]; glucoamylase activity, determined at pH 5.4 and 30°C, was reported as nanokatals per gram dry cell weight (nKat/g DCW), which is the enzyme activity needed to produce 1 nmol of glucose per second per gram dry cell weight. α-amylase activity, detected at pH 5.4 and 50°C, was expressed as Ceralpha Units per gram dry cell weight (CU/g DCW), which is the enzyme activity required to release 1 micromol p-nitrophenyl per min per gram dry cell weight.