Yeast is divided into fresh yeast and dry yeast. It is an edible and nutritious single-celled microorganism. Unlike chemical substances, it has biological activity, and there is no distinction between acid and alkali. In nutrition, it is called "inexhaustible nutrient source".

Yeast is rich in nutrients, such as protein, carbohydrates and lipids. Besides various trace elements, yeast is also rich in vitamins, minerals and enzymes.

Extended data

Yeast is a unicellular fungus, not a unit of phylogenetic classification. A tiny single-celled microorganism invisible to the naked eye, which can ferment sugar into alcohol and carbon dioxide, is distributed in the whole nature. It is a typical heterotrophic and facultative anaerobic microorganism, which can survive in both aerobic and anaerobic conditions and is a natural starter.

Generally, it refers to all kinds of unicellular fungi that can ferment sugars, which can be used for brewing production and can also be pathogenic bacteria-model organisms for genetic engineering and cell cycle research. Yeast is the earliest microorganism used in the history of human civilization. At present, there are more than 1000 kinds of yeast.

The life history of various yeasts can be divided into three types: 1. Haploid 2. Diploid 3. Monodiploid.

1, haploid

Monodiploid is represented by beer yeast.

Characteristics: Both haploid vegetative cells and diploid vegetative cells can germinate. Vegetation can exist in haploid or diploid form; Sexual reproduction under certain conditions. Haploid and diploid stages are equally important, forming generation alternation.

2. Haploid type

Haplotype is represented by Schizosaccharomyces octosporus.

Characteristics: vegetative cells are haploid; Asexual reproduction is carried out by fission; Diploid cells can't live independently, because the diploid stage is short, and they undergo meiosis as soon as they are produced.

3. Double body shape

The diploid is represented by Lutheran yeast.

Characteristics: The vegetative body is diploid, budding continuously, the vegetative stage of diploid is long, and the haploid ascospores are jointed in the ascus. Haploid stage only exists in the form of ascospores, so it cannot live independently.

References:

Baidu Encyclopedia-Yeast