Strain isolation of fermentative process

Yeast strains were isolated from inoculated and spontaneous fermentations from the commercial wineries of DO “Vinos de Madrid”. The samples were taken at density values between 1040 and 1010 g/L corresponding with the middle of fermentative phase. The samples were aseptically removed, homogenised, transferred to 100-mL sterile plastic vials, kept under refrigeration and transported to the laboratory. These samples were diluted and spread on plates with glucose-agar-chloramphenicol medium (yeast extract 5 g/L, glucose 20 g/L, agar 20 g/L, chloramphenicol 0.1 g/L, Pronadisa, Madrid). Plates were incubated at 28 °C for 48 h, after growth on plates, 20 colonies from each sample were randomly isolated and replicated on YPD and lysine agar to discriminate between Saccharomyces and non-Saccharomyces strains (Settani et al. 2012).