Difference Between Yeast and Fungi

Main Difference – Yeast vs Fungi

Fungi and yeast are two closely-related organisms, which belong to the kingdom Fungi. The main difference between yeast and fungi is that yeast is a unicellular, rounded-shape organism whereas fungi is a multicellular organism with filamentous hyphae. Yeast is a type of fungi. The multicellular, filamentous hyphae of fungi are called mold. Most mold can be seen with the naked eye in various colors. Both fungi and yeast live as saprotrophs. They secrete digestive enzymes on external food sources and absorb simple nutrients through the cell wall.

Key Areas Covered

1. What is Yeast
      – Definition, Characteristics, Role
2. What are Fungi
      – Definition, Characteristics, Role
3. What are the Similarities Between Yeast and Fungi
      – Outline of Common Features
4. What is the Difference Between Yeast and Fungi
      – Comparison of Key Differences

Key Terms: Budding, Eukaryotes, Fungal Hyphae, Fungi, Multicellular, Saprotrophs, Unicellular, Yeast

What is Yeast

Yeast is a microscopic fungus, which comprises a single, oval-shaped cell, that reproduces through budding. Most of the times, yeast is colorless. Though yeast is a single-celled organism, it is a eukaryote, containing membrane-bound organelles. Yeast can be identified in a variety of habitats, especially on plant leaves, flowers, and fruits. Most yeasts live in symbiotic relationships on the skin of warm-blooded animals. A few of them may live as parasites. For example, Candida albicans causes vaginal yeast infections. The most significant feature of yeast is its asexual reproduction method, which is budding. The daughter cell appears as a bud. S. Cerevisiae, the baker’s yeast is shown in figure 1.

Figure 1:  S. Cerevisiae

Yeast secretes digestive enzymes onto an organic material in the environment. Only simple nutrients are absorbed through their cell wall. Therefore, yeast is used in food processing industries such as baking and beer production.

What are Fungi

Fungi refer to unicellular or multicellular, spore-producing organisms, feeding on organic matter. Multicellular fungi produce fungal hyphae, which are tiny, thread-like structures. A mass of hyphae is called the mycelium. Fungal mycelium can be seen with the naked eye. Some fungi produce fruit bodies, which are edible by animals. A fruit body of fungi or a mushroom is shown in figure 2.

Figure 2: A Mushroom

The cell wall of fungi is made up of chitin. Since they are saprotrophs, fungi absorb nutrients through the cell wall. Both sexual and asexual reproduction of fungi occurs through the production of spores. Fungi are used in the production of antibiotics such as penicillin. They are also used in food processing such as cheese, tempeh and soy sauce production. Fungi cause diseases like ringworm and athlete’s foot in humans. They cause diseases in plant leaves, root, stem, as well as in crops.

Similarities Between Yeast and Fungi

• Both yeast and fungi belong to the kingdom Fungi.
• The cell wall of both yeast and fungi is made up of chitin.
• Both yeast and fungi are saprotrophs.

Difference Between Yeast and Fungi

Definition

Yeast: Yeast is a microscopic fungus, which comprises a single, oval-shaped cell, reproducing through budding.

Fungi: Fungi is a  unicellular or multicellular, spore-producing organisms, feeding on organic matter.

Habitat

Yeast: Yeast is very common in the environment.

Fungi: Fungi can be found in damp, dark or steam-filled areas.

Appearance

Yeast: Yeast is oval in shape, and is colorless and smooth.

Fungi: Fungi have a fuzzy appearance, and colors can be green, orange, black, brown, purple, and pink.

Energy Production

Yeast: Yeast converts carbohydrates to alcohol during fermentation.

Fungi: Fungi secrete hydrolytic enzymes to external food sources and absorb nutrients through the cell wall.

Reproduction

Yeast: Yeast reproduces through budding.

Fungi: Fungi reproduce through either sexual or asexual spores.

Uses

Yeast: Yeast is used in baking industry and in the production of ethanol.

Fungi: Fungi are used in the production of cheese and antibiotics.

Diseases

Yeast: Yeast causes vaginal infection in humans.

Fungi: Fungi cause diseases like ringworm and athlete’s foot in humans.

Classification

Yeast: Yeast belongs to the phylum Ascomycota and Basidiomycota.

Fungi: Fungi consist of six phyla; Chytridiomycota, Zygomycota, Ascomycota, Basidiomycota, and Glomeromycota.

Examples

Yeast: Saccharomyces cerevisiae (baking yeast) and Cryptococcus neoformans are the examples of yeast.

Fungi: Mucor, Penicillium, Rhizopus, and Aspergillus are the examples of fungi.

Conclusion

Yeast and fungi are two types of organisms, which belong to the kingdom Fungi. Yeast is a type of fungi, which is a unicellular, oval-shaped organism. Fungi are mostly multicellular, consisting of fungal hyphae. Both yeast and fungi are saprotrophs, which secrete enzymes on decaying organic matter. The main difference between yeast and fungi is their structure.

Reference:

1.“What are yeast?”  SGD-Wiki, Available here.
2. Introduction to the Fungi, Available here.

Image Courtesy:

1.”S cerevisiae under DIC microscopy” By Masur – Own work (Public Domain) via Commons Wikimedia
2. “Forest Wood Fungi Natural Fungus Mushroom Green” (CC0) via Max Pixel

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