Kingdom: Fungi Phyla and Subphyla Ascomycota Saccharomycotina (true yeasts) Taphrinomycotina Schizosaccharomycetes (fission yeasts) Basidiomycota Agaricomycotina Tremellomycetes Pucciniomycotina Microbotryomycetes Yeasts are eukaryotic microorganisms classified in the kingdom Fungi , with 1,500 species currently described [ 1 ] (estimated to be only 1% of all fungal species). [ 2 ] Yeasts are unicellular