How Fungi Could Help Save the World, Part 72
Decoding mushroom's secrets could combat carbon, find better biofuels & safer soils
Researchers at the University of Warwick are co-ordinating a global effort to sequence the genome of one of the World’s most important mushrooms - Agaricus bisporus. The secrets of its genetic make up could assist the creation of biofuels, support the effort to manage global carbon, and help remove heavy metals from contaminated soils.
The Agaricus mushroom family are highly efficient ‘secondary decomposers’ of plant material such as leaves and litter –breaking down the material that is too tough for other fungi and bacteria to handle. How exactly it does this, particularly how it degrades tough plant material known as lignin, is not fully understood. By sequencing the full genome of the mushroom, researchers hope to uncover exactly which genes are key to this process. That information will be extremely useful to scientists and engineers looking to maximize the decomposition and transformation of plant material into bio fuels.
The mushroom also forms an important model for carbon cycling studies. Carbon is sequestered in soils as plant organic matter. Between 1–2 giga tons of carbon a year are sequestered in pools on land in the temperate and boreal regions of the earth, which represents 15–30% of annual global emissions of carbon from fossil fuels and industrial activities. Understanding the carbon cycling role of these fungi in the forests and other ecosystems is a vital component of optimizing carbon management.
That however is not the end of the mushrooms talents; several Agaricus species are able to hyper-accumulate toxic metals in soils at a higher level than many other fungi. Understanding how the mushroom does this improves prospects of using such fungi for the bioremediation of contaminated soils...
To clarify a couple of trivial points on which this release goes a bit wonky, Agaricus is a genus, not a family, of mushrooms within the Agaricales, or gilled mushroom-bearing fungi. For those not familiar with the scientific name, Agaricus bisporus is commonly known as the white button mushroom; it's the one that will be most familiar to most American consumers as the mushrooms one buys at the supermarket.
Of course, the ability that these mushrooms have to concentrate heavy metals can turn them toxic under certain conditions. Having the ability to concentrate things like lead, cadmium and mercury in tissues can serve as a relatively energy-effective way for an organism to defend itself from predators without having to invest in synthesizing novel toxins. In any case, this ability is a good reason to be particularly careful about growing conditions when consuming Agaricus mushrooms; while they are quite healthy in many regards, they can be unhealthy at times. The ability to remove metals from their substrate and concentrate them in the fruiting body is one that Agaricus shares with several other fungi.
My personal favorite is Collybia iocephala; this mushroom has a particular knack for concentrating arsenic and using a few biochemical tricks to turn it into a garlic-scented gas called triarsenate. In wild, open spaces, the smell probably serves to deter predators. In enclosed spaces, on the other hand, the gas has the potential to build up and cause sickness or death. Moreover, because the mushroom is a decomposer that can grow in any damp, lignin-bearing substrate, there was a time not so long ago when it used to turn into a real problem. Until the 1920's, it was common to use pigments containing arsenic to print patterns on wallpaper. This in itself wasn't too healthy, but when that wallpaper got damp and enough C. iocephala spores germinated on it, the fun would really begin. The fungal hyphae would do what they always do, digest lignin and release triarsenate gas. People inside homes infected by the fungus would, over time, begin to suffer from arsenic poisoning. When wallpaper makers stopped using arsenic pigments this problem disappeared.
But I digress. The point here is that we're really just beginning to understand the fungi and everything they can do. It's estimated by some that only 10% of the fungi on the planet have even been identified as species to date; we don't even really know what's out there. Perhaps as we come to discover more about the species we do know, those who fund research will see more value in the most basic mycology. We've seen potential application in areas ranging from medicine to nanotechnology to alternative fuel production amongst those few species we can already point to; how much are we missing out upon by not even knowing what's in our forests, caves and oceans when it comes to organisms with chitinous cell walls that perform extra-cellular digestion?
I find myself more amazed by these organisms every time I pick up some new crumb of knowledge about them.
