Other species the researchers identified were those that were likely carried in from the outdoors, including aquatic fungi and other species that are known only to survive in association with plants. What the researchers found "wasn't just the typical mold that you think of growing on walls," Amend says.
According to the U.S. Environmental Protection Agency, mold growth on walls of homes and other buildings is primarily caused by excessive moisture; reducing humidity and preventing condensation are the recommended courses of action.
The researcher's biggest surprise was that, globally, fewer fungal species were found in dwellings located in tropical regions. In fact, fungal diversity was much greater farther from the equator in temperate climates. "This global pattern is actually the reverse of most other organisms," Bruns says. He added that for most species, greater diversity is found in equatorial regions.
The researchers suspect that these global variations may be partly due to differences in seasons and weather. For example, cooler months in temperate regions might enable the growth of organisms that cannot thrive in tropical climes. Their results, however, could also be due to global differences in socioeconomics and lifestyle or other factors not yet explored.
In the future the researchers would like to be able to detect in their samples microbes that are alive. "The sampling technique tells us that DNA is there but doesn't tell us whether the organism is alive," Bruns says. Furthermore, their samples of settled dust meant that they examined organisms that likely collected over a very broad time period. "We're definitely going to follow up with shorter timescale views of fungal diversity."
Amend notes that this study revealed some patterns of fungal colonization, and the next step would be to examine the global processes that shape those patterns. For example, he would like to know why some fungal species are widespread whereas others seem to be restricted to a single country or hemisphere. "Is this because some fungi disperse better? Is everything dispersing equally, but some are better at surviving in different environments?" Amend asks.
"This is really important," says James Scott, professor of occupational and environmental health at the University of Toronto who wasn't involved in the study. "Over the last couple of decades we've really started to appreciate how important the indoor environment is to our health, particularly the health of kids." Scott noted that the study used a fairly small sample set, and only included three locations sampled between the tropics of Cancer and Capricorn compared with nine locations sampled in temperate regions. "But it's the first look at something that is of huge interest from an environmental health standpoint," Scott says.
Scott noted that there are a lot of mixed findings about exposures to indoor fungi and their links to disease. "For the last 50 to 60 years, people interested in indoor environment and health have collected samples from the indoor environment in a certain manner. What this study highlights is that those sampling methods that have been used for quite some time were probably missing 90 to 95 percent of the biodiversity," Scott says.
"It's shocking, really. We need to start rethinking how we measure," Scott says.
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3 Comments
Add CommentBiodiversity is all fine and well, however when it comes to public health and human pathogenic response, current sampling methods show what is useful for finding and correcting problems in indoor living spaces. When correcting a problem, I want to know how much and what Genera so I can determine when a problem has been fixed. Many thousands of samples collected over the last 20 years in temperate climates that Aspergillus and Pennicilium genera (along with a few others) are by far the most commonly found associated with water intrusion damage. That same experiance also tells me that dust samples do not represent what is affecting a contaminated house although some deluded "scientists" think they can "diagnose" a facility with a single dust sample and their PCR techniques and even try to pitch this nonsense to the technically illiterate. Obviously from my comments I am concerned with the genera that cause problems and in this arena building materials and HVAC components are important.
Reply | Report Abuse | Link to thisAny facilities with pronounced temperature differentials will cause condensation of moisture. In the moisture associated with it, fungi are given an opportunity to thrive. In more subtle temperature swings, dew on foliage in climates further away from the equator have beneficial health effects, The obsession with pathology is partly with being seperated from nature with synthetics and sudden migration in and out of air conditioned zones. Silica gel heat exchangers between progressive climate zones surrounding a central habitat may be the best artificial substitute for adaptive living.
Reply | Report Abuse | Link to thisYup a very nice post and i agree with almost everything you have mentioned. It is the conditions that direct the growth of molds in an area rather then the structure and shape of the building.
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