Is yeast a fungus?

Yeast is the earliest microorganism used in the history of human civilization. it can survive in both aerobic and anaerobic environments. It is a facultative anaerobes. It is widely distributed in nature and mainly grows in acidic, moist, sugar-containing environments. According to the ability of yeast to produce spores (ascospores and basidiospores), it can be divided into three categories. Let's take a look at whether yeast is a fungus.

Is yeast a fungus?

Yeast is a fungus. Yeast is a unit of some unicellular fungi rather than a taxonomic unit. It is a general term for unicellular fungi of several families, such as ascomycetes and basidiomycetes. It generally refers to all kinds of unicellular fungi that can ferment sugars, belonging to higher microorganisms. Like higher plant cells, they have nuclei, cell membranes, cell walls, mitochondria, the same enzymes and metabolic pathways.

The reproductive mode of yeast

1. Sexual reproduction: when the nutritional status is not good, some yeasts that can reproduce sexually will form spores (generally four) and germinate when the conditions are right.

2. Asexual reproduction

① budding: mature yeast cells first grow a small bud, bud cells grow to a certain extent, continue to grow away from the mother cell, and then form a new individual.

② fission: a few species of yeasts, like bacteria, reproduce by transverse division.

③ bud cleavage: mother cells always sprout at one end and form a septum at the base of the bud, and the daughter cells are bottle-shaped. This way is rare.

Growth conditions of yeast

1. Nutrition: Saccharomyces cerevisiae needs similar nutrients like other living organisms. Like bacteria, it has a set of intracellular and extracellular enzyme systems to break down macromolecular substances into small molecular substances that can be easily used by cell metabolism.

2. Acidity: yeast can grow in the range of pH 3.0 to 7.5, and the optimum pH is 4.5 to 5.0.

3. Moisture: yeasts, like bacteria, must have water to survive, but yeasts need less water than bacteria. Some yeasts can grow in environments with very little water, such as honey and jam, indicating that they are highly tolerant to osmotic pressure.

4. Temperature: yeast cells generally can not grow when the temperature is lower than the freezing point of water or higher than 47 ℃, and the optimum growth temperature is generally 20-30 ℃.

5. Oxygen: yeasts can grow in both aerobic and anaerobic environments, that is, yeasts are facultative anaerobes that decompose sugar into carbon dioxide and water under aerobic conditions and grow faster. In the absence of oxygen, yeast breaks down sugar into alcohol and carbon dioxide.