The Shark's Paintbrush – In Praise of Fungi

September is National Mushroom Month!

You may have heard that the DNA of fungus is more closely related to human DNA than to that of plants. Did you know that the world’s largest, and probably oldest, living organism is a fungus colony living under the Malheur National Forest in Oregon? It has spread its web, or mycelium, three feet deep, under twenty-three hundred acres of land, and is estimated to be between nineteen hundred and eighty-six hundred years old. Now another type of fungus, the slime mold, and in particular the species Physarum polycephalum, is inspiring Japanese scientists to make technological systems such as computer and communications networks more robust. When fungi spread out to locate new food sources, their pathways model ideal, optimized interconnections that can teach us lessons about the design of everything from water pipe infrastructure to the World Wide Web.

What’s the difference between a mushroom, mycelium, and fungus? Fungi are not plants, animals, or bacteria. They are a kingdom with an estimated 1.5 million species, including molds and yeasts, only 5 percent of which have been identified. The mushroom is the “fruit” and “seeds” of a fungus, but the mycelium is the essential, rootlike part of the organism that lives out of sight, getting its food by decomposing organic compounds via hairlike strands that are as fine as one hundredth of a millimeter in diameter.

Fungi are not just the annoying mold blooms that we might see on overripe raspberries. Without fungi we would have no leavening for bread, no wine or beer, and no blue cheese. Mycelium is also the major operator in nature’s recycling stable. Paul’s research has generated compelling evidence that mycelium not only acts as a decomposer of all litter in forest floors but also that fungi and molds can remediate a range of problems from fetid, contaminated waste; oil spills; heavy metal deposits; and chemical insecticides to radioactive pollution and medical infections.