Fungi: Yeast vs. Mould

Fungi: Yeast vs. Mould

• Fungi are eukaryotic organisms.
• Candida is a key fungus in dentistry.
• Fungi exist in two forms: yeast and mould; some are dimorphic (both forms).

Yeast Characteristics

• Form: Grow as large single cells.
• Cell Type: Unicellular.
• Habitat: Widespread; found on fruit, in the stomach of mammals, oral cavity, and vaginal areas.
• Appearance: White and thready, usually oval.
• Hyphae: Lack true hyphae; instead form pseudohyphae (multicellular structures).
• Spores: Not a sporing species.
• Colour: Less colourful than moulds; generally colourless, collectively appearing creamy yellow.
• Oxygen: Can grow aerobically and anaerobically.
• Health Risks: Can cause infection in immunocompromised individuals.
• Reproduction: Often exhibits lateral projections (daughter cells) budding from the mother cell; some reproduce by binary fission. Pseudohyphae are chains of elongated budding cells; Candida forms these in the oral cavity.

Mould Characteristics

• Form: Grow as multiple tubular branches.
• Cell Type: Multicellular.
• Habitat: Typically found in damp, dark, or humid areas.
• Appearance: Fluffy appearance, various shapes.
• Hyphae: Composed of microscopic filaments called hyphae.
• Spores: Spore-producing fungus.
• Colour: Very colourful; can be orange, green, black, brown, pink, or purple.

Fungi: An Overview

• Diverse eukaryotic organisms including yeasts, molds, and mushrooms.
• Classified in their own kingdom, separate from plants, animals, and bacteria.
• Possess complex cells with a nucleus and membrane-bound organelles (eukaryotic).
• Cell walls contain chitin, unlike the cellulose in plant cell walls.
• Heterotrophic nutrition: obtain nutrients by absorbing organic matter. Includes saprophytic (decomposing dead matter), parasitic (feeding on living hosts), and mutualistic (beneficial relationships, e.g., mycorrhizae) types.
• Reproduction: asexual (spores, budding, fragmentation) and sexual (fusion of specialized structures/cells, spore formation).
• Growth forms: unicellular yeasts and multicellular molds (filamentous hyphae).

Molds: A Closer Look

• Multicellular fungi with filamentous hyphae.
• Important decomposers in ecosystems.
• Composed of a hyphae network that spreads over surfaces and penetrates substrates.
• Thrive in warm, humid environments on various organic materials (food, wood, fabrics).
• Reproduce via spores (air, water, insect dispersal); spores can remain dormant.
• Display a variety of colors (green, black, white, etc.) depending on spore type and substrate.

Common Mold Types

• Aspergillus: Found in soil and decaying vegetation; some species used in fermentation, others produce toxins.
• Penicillium: Produces penicillin and used in cheese production.
• Rhizopus: Found on bread and fruits; some species cause food spoilage.
• Stachybotrys ("black mold"): Produces mycotoxins harmful to health; often found in damp environments.

Significance of Fungi and Molds

• Ecological Role: Essential in nutrient cycling and decomposition.
• Food Production: Crucial in making bread, cheese, beer, and wine.
• Medicinal Uses: Source of antibiotics (e.g., penicillin) and other bioactive compounds.
• Biotechnology: Used in genetic research, enzyme production, and bioremediation.
• Agriculture: Mycorrhizal fungi enhance plant nutrient uptake and growth.

Explore the fascinating world of fungi, focusing on the distinctions between yeast and mould. This quiz covers their characteristics, growth habits, and health implications, particularly highlighting Candida as a significant fungus in dentistry. Test your knowledge on this vital topic in microbiology!