Schizosaccharomyces pombe Isolation Protocol.

This chapter describes a methodology to isolate yeast strains from Schizosaccharomyces pombe species. The method is based on a selective-differential medium that notably facilitates the isolation of S. pombe. The main difficulty in isolating microorganisms from this genus is their extremely low incidence in nature when they are compared to other microorganisms. The proposed methodology allows isolating and selecting strains from this species for industrial purposes. Methodologies allows detecting the presence of those yeasts when they are considered spoilage microorganisms. Several selective-differential agents based on the basic physiological characteristics of S. pombe species are exposed during the chapter introduction and the use is properly justified. Some of those representative characteristics are its extraordinary resistance to high sugar concentrations, sulfur dioxide, sorbic acid, benzoic acid, acetic acid, or their unique malo-ethanolic fermentation ability. The proposed selective medium is mainly based on S. pombe resistance to the antibiotic actidione and the unusual tolerance to the inhibitory agent benzoic acid compared to possible microorganisms that could produce false-positive results during an isolation process. In addition, malic acid is proposed as the main differential factor due to the exclusive ability of this species to metabolize malic acid into ethanol. This fact allows the detection of malic acid degradation. Cloramphenicol is used to inhibit bacteria growth and liquid media to avoid fungi development.