Monday 18 July 2011

Glowing Green Mushrooms Seem Pretty Magical to Me…

            If you ask me (or any mycologist) the term “magic mushrooms” isn’t nearly specific enough to describe the psychedelic variety usually implied. The truth of the matter is that lots of mushrooms are pretty darn magical. Aside from providing a tasty side dish, these fabulous fungi produce an astounding array of chemical compounds with powerful effects. From delectable truffles, to potent poisons, many mushrooms have a profound ability to spice up an otherwise bland afternoon. One of the most amazing fungal feats, however, is best appreciated not by eating, but by looking. That green glow isn’t in your head, it’s the forest night-light: fungal bioluminescence!
            Before delving into their Lite-Bright-like capabilities, we should answer the question: what exactly is a mushroom? When it comes to the world of fungi, our umbrella-shaped friends are literally just the tip of the iceberg. The mushrooms we see growing above ground (and appearing on our dinner plates) are only one part of a larger fungal organism. The Fungi are a very diverse group of organisms and have many shapes and forms. Most fungi, however, grow in an inter-connected mesh of microscopic tubes called mycelium. The cells that make up the mycelium are called hyphae. Somewhat similar to slime-mold plasmodium, hyphae are cells with multiple nuclei; and somewhat similar to filamentous algae, they grow in long strands about 20 times finer than human hair. They grow progressively longer at their tips, and branches form on existing hyphae to form complicated networks. Some mycelium networks can only be described as huge. In fact, a single fungus has been identified that is estimated to cover 900 ha and be about 9000 years old.
            Although fond of edible fungi, I can’t say I’ve ever ordered a Monterey jack and mycelium burger, so where do mushrooms come into this hyphae-delic picture? As I mentioned, mushrooms are a part of the larger fungal organism, specifically the spore-spreading part. Mushrooms are called fruiting bodies and grow above the ground to spread the spores of the underground mycelium. You can think of the fungus as a specialized structure or “organ” of the fungus that has a specific job to do: spread the genetic material of the fungus to a wider area than the mycelium is likely to grow.
Because they grow above ground, mushrooms are also “the face” that the fungus presents to the world. Like any good spokesperson, some mushrooms have an enlightening way of advertising: they glow. The neon green glow, reminiscent of glow-in-the-dark rubber toys, is a result of some very interesting biochemistry called bioluminescence. Bioluminescence literally means light from life, and it is produced by all kinds of life forms, including plants, animals, bacteria, and fungi. The two main players are luciferin (the general name for the group of pigments that are used in bioluminescence), and luciferase (the enzyme helping the reaction along). Like many things that seem pretty magical in biology, bioluminescence is all about chemistry: the luciferase combines luciferin and oxygen to make a high-energy molecule. Like Calvin after one too many bowls of Chocolate Frosted Sugar Bombs, this high-energy molecule is not very stable. It undergoes a second chemical reaction to form a lower-energy molecule, releasing the excess energy as light.
Although not the tastiest of mushrooms (and frequently rather poisonous) bioluminescent fungi have fascinated night-time forest-wanderers for centuries. Their light has been used to mark a luminous path in the woods, and even to illuminate the cabin of the early Turtle submarine. A campfire may make a good s’more, but with Nature’s amazing chemistry there is more than one way to light up the night.

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