Mushrooms May Hold Pollution Solution

Posted on Fri May 16 2008

By: Hilary Feldman in Environment, Science & Technology

Comments: 1

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First it’s fungal breakdown of elemental uranium contamination, and now fungi might help us deal with other molecular pollutants. In fact, it is such an extensive topic that entire books are being devoted to the potential of mycoremediation. In other words, the lowly mushroom kingdom, normally looked down upon due to a decaying lifestyle, might be able to decompose unwanted waste.

There are a wide range of applications, including some of the worst and most persistent compounds from pesticides and polycyclic aromatic hydrocarbons to polychlorinated biphenyls and dioxins. Advantages include the relatively low cost and rapid effect of fungal remediation.

So why are fungi so effective? The answer lies in their basic anatomy, consisting of an intricate network of tiny strands called mycelia. The mycelia absorb compounds from the surrounding soil and water, acting like a filter to remove usable materials. They then release enzymes that further break down any contaminants. This is all part of the normal process by which fungi survive and reproduce, preparing the surrounding area before fruiting - forming mushrooms - and spreading.

In fact, healthy soil contains various fungi and their extensive mycelial hyphae. For instance in the topsoil of westcoast forests, mycelia may account for up to 10% of the biomass. Mycorrhizal fungi interact with plant roots, assisting in the efficient cycling of nutrients. Most fungi examined have potential applications, such as Stropharia rugosoannulata, a saprophytic fungus known to accelerate corn growth and also able to filter coliform bacteria from water. Pleurotus ostreatus, also known as the tasty oyster mushroom, has a wide range of applications including problem nematodes and diesel fuel.

In forests, white rot and brown rot fungi attack resilient lignin and cellulose respectively. Together, these decomposers are essential to break down wood and recycle nutrients. Phanaerochaete chrysosprorium, a white rot fungus, has been used experimentally to break down dioxin and phenolic resins. Other tests have shown that various white rot fungi can attack and degrade contaminating compounds like aromatic hydrocarbons, creosote, polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), and other wastes. Once the larger contaminant molecules have been broken down into smaller components, they are rendered harmless.

However, in order to be useful on an industrial scale, further study is required to establish how to use fungi over large areas. Applying fungi can involve expensive and difficult procedures. Various substrates - from soil to wood chips to straw - are inoculated with fungal spores or mycelia. It is labour-intensive and still the subject of scrutiny and patent applications, as well as experimentation.

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