Myco = fungus
logy = study

Conidial fungi

• Conidial fungi are reproductively versatile.
• Conidial fungi produce conidia (sing. conidium), asexual spores.
• Conidia are usually spherical structures of about 5–50µm (a micrometre is one millionth of a metre). They may be a single cell, or a group of cells, of low metabolic activity.
• Sexual spores are produced, usually under adverse growing conditions – away from their favourite food, with too much or too little light, and wrong temperature – by cell fusion followed by cell division. They are rarely airborne.
• Airborne spores are called airspora.

The spores of fungi that become mould are always present in the air and on objects and will grow wherever conditions are favourable.

• Air is full of particulate material like pollen, textile fibres, skin cells, inorganic particles, and fungal spores.
• Every object which has dust on it will have some conidia in the dust.
• Spores are picked by air currents, become airborne, land on a surface and germinate.
• Germinating conidia develop into hyphae (sing. hypha). Hyphae are thread-like multi-cellular structures growing out of the spore. At their tip, they secrete enzymes into the material and absorb the soluble products as food and thus grow.

• A group or mass of hyphae that constitutes the vegetative structure of a fungus is called mycelium (pl. mycelia). In conidial fungi mycelium may take the form of a mass of threadlike filaments, branched or composing a network, on a substrate, like a mouldy spot on jam.
• The substrate is any material on which the fungus grows, e.g. jam, orange skin, paper, leather, textile.
• Please note that mould can grow on virtually any substrate, including jet fuel, paint, stainless steel, and glass. If a surface is dirty or greasy then dust will collect which is source of nourishment for mould.