Field of Science

Fungal bio-coating & soft cheeses

Fungi are some pretty amazing organisms. Molds in particular can grow in some fantastically hostile environments for example on the surface of our maple syrup. Generally things like syrups and jellies and honey are self-preserving because any bacterial cell or fungal spore that falls onto its surface is subjected to a huge osmotic differential and the tiny bit of water in the cell gets pulled into the sugary portion diluting it by some teeny-tiny amount, but of course killing the cell. But some molds can happily grow on the surface of such sugary things. The general biology of spoilage bacteria and fungi is to compete with big organisms like us for our food, and they do this by making things look, smell, and taste yucky thereby winning the competition. If they did not do this, they would simply be eaten and digested along with the food (strong negative selection). Humans have developed a taste for certain yucky things that result from controlled spoilage, for example certain cheeses that are infected on their surface by molds. In particular molds form a protective rind on the surface of soft cheeses of the camembert type that prevent infections by other spoilage organisms and keep the cheese surface dry, but the interior moist, while the mold slowly consumes and alters it with its enzymes. This rind has some pretty fantastic qualities as a bio-coating, and once this protective coating is broken the cheese needs to be consumed pretty quickly. Biologists are now looking at such bio-coatings to determine if they can have other potential uses. Research supplies: flock of goats, big cave, lots of crackers and wine. Sounds like a project it would be easy to like. Here’s a heads up for readers: try Humboldt Fog cheese, a semi-ripe soft cheese with a layer of gray plant ash running through the middle. It’s fantastic! Image credit: Artisanal Cheese. HT to the Science line.

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