Scientific Name : Saccharomyces cerevisiae
Family : Saccharomycetacea
Tamil Name :Madunam
Description: Saccharomyces cerevisiae also known as Baker’s yeast is perhaps the most useful yeast, having been instrumental to winemaking, baking, and brewing since ancient times. It is one of the most intensively studied eukaryotic model organisms in molecular and cell biology. Saccharomyces when translated means “sugar fungus”
Distribution and status: Baker’s yeast is a cosmopolitan organism and is used daily by human beings.
Habitat: It is believed to have been originally isolated from the skin of grapes (one can see the yeast as a component of the thin white film on the skins of some dark-color fruits such as plums; it exists among the waxes of the cuticle). Many proteins important in human biology were first discovered by studying their homolog in yeast; these proteins include cell cycle proteins, signaling proteins, and protein-processing enzymes.
Habits: Baker’s Yeast is Eukaryotic and single cell organism. Yeast gets its food from glucose. In nature, yeast cells are found primarily on ripe fruits such as grapes (before maturation, grapes are almost free of yeasts). Since S. cerevisiae is not airborne, it requires a vector to move. In fact, queens of social wasps overwintering as adults (Vespa crabro and Polistes spp.) can harbor yeast cells from autumn to spring and transmit them to their progeny.
Food: Baker’s yeast is commonly isolated from human, mammals, birds, wine, beer, fruits, trees, plants, olives, and soil.
Life cycle : Reproduction is done by both sexual and asexual method. Two forms of fungal yeast cells can survive and grow: haploid and diploid. The haploid cells undergo a simple lifecycle of mitosis and growth, and under conditions of high stress will, in general, die. This is the asexual form of the fungus. Under conditions of stress, diploid cells can undergo sporulation, entering meiosis and producing four haploid spores, which can subsequently mate. This is the sexual form of the fungus.
Role in the environment : The yeast species S. pombe and S. cerevisiae are both well studied; these two species diverged approximately 600 to 300 million years ago, and are significant tools in the study of DNA damage and repair mechanisms. S. cerevisiae has been highly studied as a model organism to better understand aging for more than five decades and has contributed to the identification of more mammalian genes affecting aging than any other model organism
Photo source: http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae