Saccgaromyces cerevisiae is known as “baker’s or brewer’s” yeast and is a model species for studying fungal pathogenesis. Besides the typical staining through the Gram stain, other stains that are usually done include:
-Calcofluor white which is a typical blue dye that binds to cellulose and chitin
-Concanavalin A (conA) which is a lectin that binds to alpha-mannopyronosyl and alpha-glucopyranosy residues located in the cell wall and is stained in various colors
-Wheat Germ Agglutinin (WGA) which is another lectin that binds sialic acid and N-acetylglucosamine
-Thiazole orange that is a green dye for yeast cytoplasmic and nuclear localization
-ViaFluor which is a green dye that is hydrolyzed through esterase enzymes that causes release of the active component called carboxyl-fluorescein SE
Amongst the various other dyes commercially used in the clinical microbiology.
Clinically, Saccharomyces is being seen as an emerging pathogen in immunocompromised patients and thus is a opportunistic mycoses that can be used to cause pneumonia, endocarditis, liver abscess, fungemia, and sepsis.
When stained with the typical Gram Stain, ascospores (appear when grown on V-8 medium/acetate ascospor agar/Gorodkowa medium) which are globose and are located in asci which each individual ascus containing 1-4 ascospores that usually rapture on maturity. are seen microscopically as gram negative while the vegetative cells are gram positive.
A good source to read about the membrane of this species is the follow link