Penicillium
As Penicillium you would be the blue-green fuzz on a forgotten orange – an unglamorous life, except that one of your relatives changed the course of medicine.
Little brushes
Penicillium is a genus of several hundred species of mould fungi. Its body is a network of microscopic threads, hyphae, that grow into food or soil and digest it with secreted enzymes. Reproduction gives the genus its name: upright stalks branch into chains of spores that look like a tiny brush, Latin penicillus. Each colony releases enormous numbers of dry spores into the air, which is why Penicillium turns up on bread, fruit, damp walls and almost any neglected leftovers.
Spores are only a few micrometres across. You would spend most of your life as one of them, drifting through the air until you landed on something moist and edible.
The mould that made medicine
In September 1928 Alexander Fleming returned from holiday to find a mould colony on a staphylococcus plate surrounded by a clear zone where bacteria had died. He named the active substance penicillin. Turning it into a drug took the work of Howard Florey, Ernst Chain and colleagues in Oxford from 1939, and mass production in the United States during the Second World War. The best-producing strain came from a mouldy cantaloupe melon bought in a market in Peoria, Illinois, in 1943. Fleming, Florey and Chain shared the 1945 Nobel Prize.
On the cheese board
Other species are welcome in the kitchen. Penicillium roqueforti produces the blue veins of Roquefort, Gorgonzola and Stilton, and Penicillium camemberti forms the white rind of Camembert and Brie. Not all Penicillium is friendly, though: some species make mycotoxins, and spores can trigger allergies, so mouldy soft food is best thrown away rather than scraped. Your life as a colony would end when the food was used up, the bin lorry came or someone finally cleaned the fridge.
