ABSTRACT
For thousands of years man has made profit on the products synthesized by yeasts. In the beginning it was bread leavening, beer and wine fermentation, alcohol production later on yeasts provided man with other products such as glycerol, enzymes, coenzymes and vitamin. Yeasts of industrial interest reproduce asexually by budding. Ascosprogeneous yeasts under certain environmental conditions can reproduce sexually, leading to the formation of ascospores. In the budding process a small localized area of the cell wall protrudes outwardly; cytoplasm from the parent cell streams into the area, nuclear material replicates by mitosis and one of the daughter nuclei moves into the distended protuberance. The developing bud continues to increase in size until it attains about a third of the size of the mother cell. Ascomycetous yeasts can reproduce sexually through a cycle that involves altering the haploid and diploid states of their life-cycles and leads to the production of sexual spores in an ascus.
