Yeasts are the non-mycelial (unicellular) saprotrophic ascomycetes. They are also cosmopolitan in distribution that grows in sugar-rich medium, milk, sweet fruits, decaying vegetables & some on animal excreta.
Types of yeast:
True yeasts (ascosporic yeasts): Develop ascospores inside the asci or ascocarps. They generally include 68 species belong to 14 genera, e.g., Saccharomyces, Zygosaccharomyypces. Schizosaccharomyces, Nodosonia. Pichia etc.
False yeasts (asporogencus yeasts): Similar to the true yeasts but they don’t form spores or asci. They are also included under Deuteromycetes (fungi imperfecti), e.g. Candida, Mycoderma etc.