There is a serious need to develop authoritative, reliable identification system for indoor fungi. Indoor moulds concern the medical profession and the general public for several reasons, and the proposed research would be a logical extension of the Sloan’s portfolio on the microbiology of the Indoor Environment.
Moulds are often introduced into buildings and multiply on mouldy food, or sometimes on mouldy building materials, with xerophilic moulds (i.e. species able to grow with minimal moisture) often found in house dust. Changes in building practices stimulated by increased oil prices have led to construction of tightly sealed buildings, prone to developing moisture problems that promote fungal growth. Increased use of immunosuppressant drugs and the advent of AIDS resulted in increased frequency of human fungal infections, including infections caused by species not previously considered pathogens. There is strong indication that increased childhood asthma and allergies may be related to mould exposure. Dramatic weather events, such as flooding of the Mississippi Valley (1993) and Hurricane Katrina (2005), resulted in massive mould contamination of buildings, and substantial losses for families and insurance companies. Contrary to expectations, the indoor mycobiota differs from the outdoor air mycobiota.
The species diversity of fungi within individual samples is likely to be enormous, and it is expected to identify many species previously unreported in the indoor environment, and several species new to science. Stachybotrys chartarum, often referred to as ‘toxic black mould’, is synonymous with danger to homeowners, and has resulted in spectacular legal cases and hysterical media coverage. Taxonomically, Stachybotrys includes about 35 species, with six species occurring in buildings. These species grow on wet, cellulose-rich materials, such as dry wall (= gypsum board) in flooded basements. One of the two chemotypes of S. chartarum produces cyclic trichothecene mycotoxins, such as satratoxin, but the morphologically similar sister species S. chlorohalonata does not. Although S. chartarum is associated with dramatic events such as the death of infants in Cleveland in 1994, it is unclear how this fungus could cause such severe health effects, or whether it deserves the attention it receives.
Moulds can be observed directly on building materials and contents, and isolated and sometimes identified directly from this growth. Because many indoor fungi are xerophilic, requiring little free water to grow, profiling of species in any building should use at least two isolation media, one for mesophiles (species growing in moist environments) and one for xerophiles. Some xerophiles are associated with house dust mites, and this interaction is significant for asthmatics and allergy sufferers. The moulds detected by this combination of methods comprise a list of about 200 species, although this is biased by the number of studies in northern Europe and North America.
On the international scale, studies of indoor moulds often employ different methods. Many practitioners trap and count spores, with tentative generic identifications based on spore micromorphology, but this lacks taxonomic precision. This database on indoor molds will be the base for a more reliable identification.