Fungi are eukaryotic organisms and include yeasts, mould and mushrooms. Some fungi are multi-cellular, while others, such as yeasts, are unicellular. Most fungi are microscopic but many produce the visible fruiting bodies we call mushrooms. Fungi can reproduce asexually by budding, and many also have sexual reproduction and form fruiting bodies that produce spores.

Most fungi live in the soil or decaying matter, breaking down organic matter for energy, and so form an important role in nutrient cycling and decomposition. Some fungi live on or in living organisms and get their energy directly from the cells they are living on. The symbiotic relationship between the fungi and their host can benefit both (mutualism), benefit just the fungi and not affect the host (commensalism) or be detrimental to the host (parasitism).

Fungi have long been part of our diet as mushrooms but are also used in baking and brewing. Yeasts are the rising agent in bread and are used to ferment sugars to create alcohol. More recently, yeasts have been used to create biofuels from the fermentation of ethanol from plant sugars.

Nature of science

Many great scientific discoveries have come from observations of ‘accidents’. These mistakes have often led the scientist in an unexpected direction. It takes powers of observation and an open and curious mind to take advantage of these chances.

In 1928, Alexander Fleming discovered a bread mould had contaminated a bacterial plate he was studying. His observation that the fungi had killed the bacteria that surrounded it lead to the discovery of penicillin. "When I woke up just after dawn on September 28, 1928, I certainly didn't plan to revolutionise all medicine by discovering the world's first antibiotic, or bacteria killer," Fleming would write later, "but I guess that was exactly what I did. "It took over 10 years of research by many teams of scientists to produce penicillin in a stable form and to mass produce it, but when they did, it was soon hailed as a miracle cure.

Penicillin is a natural antibiotic produced by the fungus to prevent bacteria from invading it. Since this discovery, several antibiotics have been discovered from different fungi.

When fungi invade living cells, they are capable of forming disease in plants and animals. Fungi are responsible for the human diseases thrush, athlete’s foot and ringworm. Fungi can also cause disease in plants, such as Dutch Elm disease and rice blast disease. They are also a common cause of food spoilage, especially if food stores get damp, as these conditions are suitable for fungal spores to germinate.

 

    Published 9 November 2008