Penicillium. Coloured scanning electron micrograph of fruiting bodies (conidia) of the fungus Penicillium. The fruiting bodies grow at the tips of hyphae (threads) and consist of chains of round spores, each of which can germinate into a new fungus. Penicillium produces the antibiotic drug penicillin, which was discovered accidentally by Alexander Fleming in 1928 when his bacterial culture dish became contaminated with the fungus. The discovery revolutionised medicine and won Fleming the Nobel Prize in 1945. Magnification unknown.