Indoor Air Quality: Fungi Q & A
These are some of the common questions professionals are asked regarding indoor air sampling:
Most pathogenic fungi are culturable with modern media (we learned to culture rust (e.g. Pucinia back in the 1950’s..) Some organisms such as Stachybotrys are easily cultured... but because of spore production in slime, they are often not ‘captured’ in air samples. These types of fungi are identified from swabs or scrapings submitted to the lab. MBL uses/recommends a minimum of 3 different media for sample collection. This is partly to allow for diverse growth requirements of different fungi and partly to restrict the growth of some saccarophyllic organisms such as Mucor sp., bacteria and yeasts. Overgrowth of organisms is a common problem but can easily dealt with in a competent lab. Individual spores or propagules can be counted on culture plates if required. If the titre is low - that in itself is significant.
Seasons and even changes in the microclimate (e.g. Gold has shown that sudden drop in local humidity is necessary to release spores.) certainly have an effect on titres. Such information is used by professionals to interpret the data.
I can only speculate: Mycology is very labour intensive and requires extensive training. Some 25 years after getting my PhD I am still actively learning. The regulatory agencies must dictate rules and means that are widely attainable. Mycologists and competent laboratories are not common.
It is NOT an either/or situation. Cultured fungi give certainty to the identity of the organism and allows a health expert to judge potential dangers better. Particle counts are important and well recognised. Specific guidelines are widely published.
Depends on the organisms present, but often the taxa present are quite suggestive: for example, presence of Trichoderma and Chaetomium as opposed to Botrytis, Fusarium and Alternaria would suggest relatively dry conditions; Chaetomium sp feed on cellulose and many Asparagilii are capable of withstanding relatively dry conditions. Botrytis grows on rich rotten plant material or has been blown in from there. Trichoderma is a primary coloniser e.g. sterile or freshly cleaned surface. it does not compete well later, in more complex environments e.g. soil. here is no substitute for a professional with experience in the field. But surely it would be a shame not to utilise ALL available knowledge to help ensure people's health.