There’s No Social Distancing from Your Fungal Housemates
Submitted by: Rachel Adams
While many are thinking of fungi while at home, I continue to think about fungi in homes. That is, the fungi that grow in buildings because of water damage. Most people are surprised to learn that we haven’t found what aspect of fungi to measure in buildings that would tell us if the building poses a health risk to occupants, or even if there’s water damage at all. Three thousand years after the Book of Leviticus advises on how to cleanse a home of “defiling mold”, we can still give only vague guidance on which homes need that cleansing.
The number of fungal species in house dust is essentially unbounded – a combination of what blew in the window or came in through the ventilation system, what we brought in on the soles of our feet and on our clothing, as well as what we and our pets shed. It is likely this rich tapestry of environmental fungi that make the fungi that are actually growing in our homes so difficult to spot. As a researcher currently working on fungi in the build environment, one angle I’m pursuing is looking for particular groups of fungi based on their water requirements for growth. Many fungi can tolerate low levels of moisture in their growth substrate – for example, there are species like Wallemia sebi that can grow on material with the moisture equivalence of dried fruit. On the other end of the extreme is the infamous Stachybotrys chartarum, which requires nearly standing water. It could be that by looking to not individual species but broader groups of species defined by their ecologies, the signal of water damage will become brighter.
Another strategy I’m pursuing is looking for chemicals that microbes in homes emit. Working with chemists that have an “electronic nose,” an instrument that can detect and measure miniscule concentrations of airborne chemicals, we have begun to explore the moisture conditions around which microbes in homes become active. Fungi are impressive chemists, capable of transforming recalcitrant material into biomass. They are also hardy ones. In order to disentangle the chemical emissions by fungi from the dust itself, we sent samples of household dust to a company whose main business is sterilizing medical equipment with intense radiation. Even after subjecting the dust to gamma radiation, some fungi (and bacteria) remain alive. We are going to have to try harder to kill these microbes.
In a dry home, these fungal housemates go unnoticed; but in a home in which water is available where it shouldn’t be, these fungi demand attention. As I spend more time than ever with my fungal housemates, I’m working from home to reveal their secrets.