False-colour scanning electron micrograph (SEM) of the fungus Penicillium sp., source of the first antibiotic drugs to be discovered. Commonly known as a mould growing on bread. Here, fungal threads of the vegetative mycelium are seen (green); a spore-bearing structure known as a conidiophore (blue, at centre) imparts a blue-green colour to this fungus. Spores (conidia) resemble beads strung together in a chain. Once ripe, each spore can germinate into a new fungus. Penicillin was first produced from Penicillium notatum, effective against a range of bacteria; antibiotics are now more selective as drugs against specific micro- organisms. Magnification: x685 at 6x7cm size.