Thursday, Jul 24, 2008
Although mycoremediation sounds "Brave New World"-ish, the concept behind it is decidedly low tech: think home composting, not genetic engineering. Most gardeners know that a host of microorganisms convert organic material such as rotting vegetables, decaying leaves and coffee grounds into the nutrient-rich soil required for plant growth. Fungi play a key role in this process. In fact, one of their primary roles in the ecosystem is decomposition. (Hence the killer-fungus scenario of many a science fiction novel, not to mention the moldy bread and bath tiles that are the bane of modern existence.)
The same principle is at work in mycoremediation. "We just have a more targeted approach," says Stamets. "And choosing the species [of fungi] that are most effective is absolutely critical to the success of the project."
Fungal decomposition is the job of the mycelium, a vast network of underground cells that permeate the soil. (The mushroom itself is the fruit of the mycelium.) Now recognized as the largest biological entities on the planet, with some individual mycelial mats covering more than 20,000 acres, these fungal masses secrete extra cellular enzymes and acids that break down lignin and cellulose, the two main building blocks of plant fiber, which are formed of long chains of carbon and hydrogen.
As it turns out, such chains are similar enough to the base structure of all petroleum products, pesticides, and herbicides so as to make it possible for fungi to break them down as well. A couple of years ago Stamets partnered with Battelle, a major player in the bioremediation industry, on an experiment conducted on a site owned by the Washington State Department of Transportation in Bellingham. Diesel oil had contaminated the site, which the mycoremediation team inoculated with strains of oyster mycelia that Stamets had collected from old-growth forests in the Pacific Northwest. Two other bioremediation teams, one using bacteria, the other using engineered bacteria, were also given sections of the contaminated soil to test.
Lo and behold. After four weeks, oyster mushrooms up to 12 inches in diameter had formed on the mycoremediated soil. After eight weeks, 95 percent of the hydrocarbons had broken down, and the soil was deemed nontoxic and suitable for use in WSDOT highway landscaping.
By contrast, neither of the bioremediated sites showed significant changes. "It's only hearsay," says Bill Hyde, Stamets' patent attorney, "but the bacterial remediation folks were crying because the [mycoremediation] worked so fast."
And that, says Stamets, was just the beginning of the end of the story. As the mushrooms rotted away, "fungus gnats" moved in to eat the spores. The gnats attracted other insects, which attracted birds, which brought in seeds.
Call it mycotopia.
"The fruit bodies become environmental plateaus for the attraction and succession of other biological communities," Stamets says. "Ours was the only site that became an oasis of life, leading to ecological restoration. That story is probably repeated all over the planet."
At Fungi Perfecti, a rural compound not far from Aberdeen, Wash., signs warn visitors not to enter without an appointment, and security cameras equipped with motion sensors guard several free-standing laboratories and a mushroom "grow" room. "My concerns are personal safety and commercial espionage," says Stamets, explaining that competitors and mycological hangers-on (not always a stable lot, apparently) have a tendency to show up unannounced.
Then there's the small problem of marketing a product associated in some people's minds with illegal substances. In the late 1970s, Stamets did pioneering research at Evergreen State College on psilocybin hallucinogenic mushrooms; he later published a definitive identification guide: "Psilocybin Mushrooms of the World."
"I drew the line a long time ago," says Stamets. "But I'll never be an apologist for that work. Everything I did was covered by a DEA license."
Today, Stamets spends much of his time cloning wild mushrooms. One of his innovations has been identifying strains of mushrooms with the ability to decompose certain toxins and adapting them to new environments. With the benefit of computer clean-room technology, Stamets introduces samples of toxins to mycelia growing on agar culture, then screens the samples to see if the mycelia are actually metabolizing the toxin. You can actually train the mycelia to grow on different media, he says.
As reported in Jane's Defence Weekly, one of Stamets' strains was found to "completely and efficiently degrade" chemical surrogates of VX and sarin, the potent nerve gases Saddam Hussein loaded into his warheads.
"We have a fungal genome that is diverse and present in the old-growth forests," says Stamets. "Hussein does not. If you look on the fungal genome as being soldier candidates protecting the U.S. as our host defense, not only for the ecosystem but for our population ... we should be saving our old-growth forests as a matter of national defense."
Stamets recently collaborated with WSDOT on another mycoremediation project designed to prevent erosion on decommissioned logging roads, which channel silt and pollutants toward stream beds where salmon are reproducing. In a process Stamets terms "mycofiltration," bark and wood chips were placed onto road surfaces and inoculated with fungi. The mycelial networks not only helped to build and retain soil but also filtered out pollutants and sediments and thus mitigated negative impacts on the watershed.
Stamets envisions myriad uses of mycofiltration, one of which involves bridging the gap between ecological and human health. It's been more than 70 years since Alexander Fleming discovered that the mold fungus penicillium was effective against bacteria. And yet, complains Stamets, nobody has paid much attention to the antiviral and antibiotic properties of mushrooms -- partly because Americans, unlike Asian cultures, think mushrooms are meant to be eaten, not prescribed. But with the emergence of multiple antibiotic resistance in hospitals, says Stamets, "a new game is afoot. The cognoscenti of the pharmaceuticals are now actively, and some secretly, looking at mushrooms for novel medicines."
Based on a recent study documenting the ability of a mushroom, Polyporus umbellatus, to completely inhibit the parasite that causes malaria, Stamets has come up with a mycofiltration approach to combating the disease. "We know that these fungi use other microorganisms as food sources," he says. "We know they're producing extracellular antibiotics that are effective against a pantheon of disease microorganisms. We can establish sheet composting using fungi that are specific against the malarial parasites. We can then go far in working with developing countries, in articulating mycelial mats specific to the disease vectors in which these things are being bred."
Stamets is currently shopping this idea around to the Bill and Melinda Gates Foundation, a front-runner in the effort to provide vaccinations in developing nations.
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