General characteristics of Yeast

General characteristics of Yeast

Yeast is basically chemorganotrophs as they can use the inorganic chemical as a source of energy.
Mostly yeast isolated from the surfaces of fruit and berries like apple, peaches and exudates from plants such as plants saps or cacti.
Yeast can be present in the gut flora of mammals and some insects and even in the deep-sea environment.
Yeast mostly grows at a temperature ranging between 20 to 28 degree Celsius at an acidic pH of 3.5 to 4.
For maintenance and preservation of yeast culture slant with 2%, caco3 can be used.
Classification of yeast can be done using its morphological characteristics, cultural characteristics and sexual characteristics and physiological characteristics.

Morphological characteristics:-

The characteristics of vegetative reproduction and a vegetative cell can be used to classify yeast.
Vegetative reproduction is done either by fission or by budding or by the formation of conidia.
Reproduction by fission is a typical characteristic of endomycetacea.
Morphology of the vegetative cells cultivated in liquid and solid media is founded on whether the cells are spherical, ovoid, cylindrical etc.

Cultural characteristics:-

Yeast grown in watery media may result in the formation of residue a ring, a pellicle.
Pellicle formation on a watery medium is a product associated with oxygen demand of yeast.
Growth on solid media may be either butyrous, friable, pigmented.
Lipomyces shows characteristics of mucoid growth.

Physiological characteristics:-

Yeast developing on a carbon source must either be able to format it or utilise it by respiration.
It has been found that when yeast utilises carbon source fermentatively it is also able to utilise it oxidatively.
The ability or inability to ferment carbohydrates to ethanol and carbon dioxide is the most important for differentiating spaces.
Variety of sugars is formatted by a variety of yeast.
Nitrogen metabolism is the fundamental feature of development the ability or inability to utilise various derivations of nitrogen can be made use of in classifying yeast.
The use of the ability or inability to grow in a synthetic medium devoid of vitamins like biotin and folic acid, inositol etc.
Except for genus saccharomyces which only grows in media containing certain east or protein hydrolysates all yeast can utilise a variety of nitrogen sources.
Practically every yeast uses urea at low concentration as a single source of nitrogen contributed that a sufficient amount of vitamins are supplied.
Fermentative yeast from a variety of oysters is varying amounts.
Ethyl acetate has been found to be the commonest and the most readily detectable Easter formed by yeast.
It is approved that the potential of yeast to soften gelatin is a very restricted taxonomic importance as very few are strongly proteolytic.

Sexual characteristics:-

Sexual characteristics involve the presence of the mode of ascus formation is characteristic of homothallic species.

Reference