Of Allergies and the Lives of the Indoor Molds

I moderated an actual comment about fungal allergens in Alabama. I get a few comments every now and then, but almost all of them are spam. I figure the few of you who may check in with me don't need to read any more ads for erection pills and other medications.

However, Shalleen asked an interesting question that I thought merited my research, even though it's a bit out of my wheelhouse.
Please note that I'm not trying to peddle medical advice. I am most certainly NOT a medical doctor. My perspective is that of a mycologist.

Allergies are extreme immune events which can be caused by breathing in of allergens. Pollen is a common allergy. I suffer from pollen allergies, which my father thought was ironic, given my training as a botanist. But overexposure to potential allergens can lead to increased sensitivity. I often tell people the worst part of having allergies and being a botanist is KNOWING what the pollen is trying to do to my nose.

Pollen is the source of the male gametes in seed-producing plants. Thus, pollen is analogous to sperm in animals. Produced in prodigious quantities, pollen requires a relatively small investment of energy, and each has a very low probability of fulfilling its purpose, fertilization of an ovule. Pollen is analogous to email spam or phishing in this way. Even though most of it is emitted without achieving its purpose, it is the rare hits that have a big payoff that make the investment of energy worth it.

Fungal spores are similar to pollen in that they are produced in great quantities with little chance for success at the individual level. How great a quantity? According to Bryce Kendrick's "The Fifth Kingdom", a single Ganoderma applanatum conk can release 30 BILLION spores A DAY!
Compare that with an estimate of 85 million sperm produced by a human male in a day, and you can see that spores are quite abundant in the air.

I should note, medical mycology is not for the faint of heart. The number of fungal pathogens of humans is relatively small relative to both the number of fungal species and to the number of biotic human pathogens (including viruses and bacteria). However, some of those few fungi that cause mycoses (singular: mycosis, inflammatory diseases caused by fungi) tend to disfigure people in grotesque ways. Google Image Search at your own risk.

As for Alabama specific allergenic fungi, I do not know of any such list. However, a paper was recently published in the eminent Proceedings of the National Academy of the Sciences (PNAS) which examined the fungal community in dust samples from 76 locations throughout the world, in both temperate and tropical on six continents, and in several types of buildings. A Scientific American article discussing the paper can be found here. Using high throughput sequencing (454 sequencing) they were able to examine the fungal community in dust samples. Using PCR primers specific to fungi, the researchers were able to amplify fungal genes in the dust sample, including many that may not be have been revealed by simply culturing. The primers anneal to sites that (ideally) all fungi possess but non-fungi do not, and amplify regions that are more free to vary. Each unique variation of that gene in the large sample is a haplotype, which can then be compared to known sequences in GenBank and classified by their similarity to known values. By looking at the different haplotypes, researcher identify Operational Taxonomic Units, or OTUs. In some cases an OTU represents a known species, matching 100% completely with a GenBank sequence, but most sequences are only close matches, in which case they may come from undescribed species, or be different population of previously described species, or just something entirely new, in which case a best BLAST match can only be at the family level or above. Thus OTUs are the diversity units. Among the most interesting results are the relative diversity of fungal OTUs in the tropics compared to the temperate regions. In most living taxa (plants, animals, other fungi), diversity is greater in the tropics than in the temperate regions. In the case of the dust samples, there were more fungal OTUs in the temperate samples on either side of the tropics.

Also, they found greater similarity in fungal communities that were relatively clustered spatially than in similar construction. Thus a residential home was more likely to share OTUs with a nearby warehouse than a residential home further away. Thus, it is likely that Alabama does have a locally unique indoor mycota (list of fungal species), but that remains to be explored. Hopefully it's not much much too late for you, Shalleen.