With the recent popularity of “green” buildings, we have to wonder how these new materials affect the microbes in the built environment. This 2010 paper from researchers at the University of Texas examines fungal growth in such materials. The study involved artificially and naturally inoculating four green building materials and their non-green counterparts with Aspergillus niger, as well as testing water capacity.
They found that a material’s capacity to hold water provided a great environment for the fungi to grow in, so materials with a high capacity tended to have more fungal growth. The high humidity in building components is what encourages A. niger and other fungi to grow happily. Interestingly, conventional ceiling tiles had the most water capacity, while green sunflower board and conventional hardwood flooring held the least. After artificial inoculation and subsequent 8 weeks of observation, the conventional ceiling tiles, conventional gypsum board, and green paperless drywall showed fungal growth, while the rest of the materials showed no growth. Gypsum and drywall actually contain a great food source for the fungus. The study also did natural inoculation and observed that green sunflower board supported the most growth, while the rest of the samples showed little or no fungal growth.
The study’s overall conclusion was that the green materials tested were not more or less prone to fungal growth. Each individual material varied from the next, independent of whether it was “green” or not. Building materials should instead be evaluated on the basis of how well a spore can establish growth initially, and whether there is enough food source and humidity to allow it to subsist.
Alex Alexiev is an undergraduate in Jonathan Eisen’s lab, working on aquariums as part of the microbiology of the built environment