Wellcome Trust Blog

Penicillin producing penicillium

Our image of the week depicts the mould Penicillium, which produces the antibiotic penicillin. Moulds are a type of fungus, and reproduce using the spores that you can see in the picture. The Penicillium mould in this particular image was growing on the surface of bread.

The image was taken by Debbie Marshall and David Gregory in 1983 using a scanning electron microscope (SEM). To capture it, they took a small sample of the mouldy bread and chemically fixed it to make it more stable for the microscopy procedure. It was then washed with distilled water and dehydrated using ethanol and carbon dioxide to make it completely dry. The bread samples were then mounted on aluminium stubs, attached with adhesive containing silver and coated with tiny (20 nanometre, or 0.00002mm) fragments of platinum to make them conductive. After this preparation, the SEM image could be taken. Colour was added…

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