When I hear fungi, I think of mushrooms – both delectable and deadly. But there’s another world of fungi buried in the soil. These fibrous microbes might be able to help clean up polluted soil.
I’ve always thought of bacteria as nature’s decontamination crew. Bacteria already munching on oil from natural seeps in the Gulf of Mexico flourished after the 2010 Macondo well blowout in the Gulf of Mexico. Several different groups of microbes ate their way through much of the hydrocarbons in the oil within a few months of the well being capped.
Oil-eating bacteria live in the soil too, but they have a harder time reaching food than their aquatic relatives. Soil is packed with air pockets that bacteria and chemicals must detour around as they move through the soil. That means natural microbial degradation of oil takes a long time. To speed the process, people often plough oil-contaminated soil to mix pollutants and bacteria.
Fungi sprout thin shoots called hyphae as they grow through the soil. These fibers intertwine in a network called a mycelium. The mycelium of the largest fungi covers more than 1000 football fields.
Lukas Wick, of the Helmholtz Center for the Environment in Germany, and his colleagues think fungi might be able to help clean up contaminated soil. Fungi can eat metals, medicines, and ingredients in plastic. Bacteria struggle to digest the complicated structures of these molecules. And even when bacteria can degrade a pollutant, they require a contaminant buffet. Fungi, however, can process a steady stream of pollutants.
Fungi have another green cleaning benefit hidden in their structure. Contaminants and bacteria can travel along their mycelial networks, effectively mingling as if the soil had been ploughed. These networks are made of thin fibers called hyphae, which filamentous microbes use to transport nutrients through their bodies.
A filamentous microbe related to fungi can pump oily hydrocarbons through its hyphae. And bacteria can float through the watery film covering the hyphae, using the fungal network as a highway through soil to find new patches of pollutant food.
The idea of a fungal environmental clean up crew may be exciting, but it’s not ready for real world action yet. Scientists are still learning how to encourage the growth of fungi and their hungry bacterial neighbors, especially in contaminated places.
Wick hopes to eventually encourage both microbes to grow in contaminated soils so that oily contaminants might degrade faster than if bacteria alone were stuck with the job.
So the next time I see a fungus in the woods, I'll still stop to admire the colors of its mushroom. But I'll think about what's underneath the soil too.