A Fungal Fresco
While this might look like an impressionistic painting of a lush bouquet, it’s actually a microscopic image of mold growing in a culture dish. In fact, if you’ve ever wondered what the fuzz on those strawberries lingering in your kitchen looks like up close, you came to the right place.
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DownloadA Fungal Fresco
While this might look like an impressionistic painting of a lush bouquet, it’s actually a microscopic image of mold growing in a culture dish. In fact, if you’ve ever wondered what the fuzz on those strawberries lingering in your kitchen looks like up close, you came to the right place.
What am I looking at?
This is an image of the hyphae, or threads, and fruiting bodies of an Aspergillus fungus. The tubelike branching structures are the hyphae (1), which make up the mycelium that is the main “body” of a fungus. The flowerlike structures are the fruiting bodies (2), which produce tiny, spherical spores called conidia that are used in reproduction. The dense line of hyphae toward the bottom of the image (3) demarks the surface of the agar that this fungus is growing on.
Click on the right arrow to see some additional views of Aspergillus fungi.
Biology in the background
Aspergillus is a common mold that grows on all sorts of organic matter. This specimen was grown on agar, a gelatinous culture medium, inoculated with a Q-Tip that had been swabbed against the skin of an onion. Molds prefer to grow in carbohydrate- or sugar-rich environments, which is why they are often found on fruits and vegetables. In fact, the ability of molds to break down starches and other complex carbohydrates makes them useful in producing alcoholic drinks like sake, which is brewed from rice using a yeast called koji that contains cultures of Aspergillus oryzae.
Other species of Aspergillus produce penicillin, the first broad-spectrum antibiotic ever discovered. Alexander Fleming’s identification of the healing properties of penicillin molds in 1928 revolutionized medicine. The strain of fungus that became the main producer worldwide of penicillin was isolated from a particularly fuzzy cantaloupe found at a local market by Fleming’s assistant, Mary Hunt, nicknamed “Moldy Mary.” Molds are also used in the production of citric acid, used to ripen certain cheeses, and in bread-making.
But not all species of Aspergillus are beneficial. Some can cause fungal infections in humans, using open wounds or the lungs as an entry point to the body. And certain species produce mycotoxins, such as aflatoxins, which are both poisonous and carcinogenic.
The hyphae of this fungus can grow to about 8 micrometers thick, or roughly 10 times smaller than the width of a human hair.
Technique
These images were created using confocal microscopy.
Igor Siwanowicz, HHMI's Janelia Research Campus