Fungus Fact Friday

Category: Fungus Fact

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Fungus Fact

#164: Histoplasmosis

Histoplasmosis is a fungal disease caused by the fungus Histoplasma capsulatum. Like the other true human fungal pathogens, H. capsulatum lives as a mold in the environment but switches to an infective yeast form in the body. In nature, H. capsulatum grows on bird or bat droppings. This fungus is very common, especially in the Ohio and Mississippi River valley areas. However, H. capsulatum very rarely causes disease. As with most fungal diseases, people with a weakened immune system are most at risk of acquiring histoplasmosis.

Endospore release 0

Fungus Fact

#163: Valley Fever, Coccidioidomycosis

Coccidioidomycosis, otherwise known as “Valley fever,” is the most virulent human fungal pathogen. The disease is caused by the fungi Coccidioides immitis and C. posadasii, which normally live in arid soils. When they are disturbed by wind, construction, or human activity, spores from these fungi can become airborne and end up in peoples’ lungs. There, the spores germinate and can cause infection. Most of the time, the infection is mild and does not need to be treated. Occasionally, however, this progresses to more severe forms that sometimes require lifelong treatment. As with other human fungal diseases, Valley fever is more likely to cause severe disease in people with weakened immune systems.

Candida albicans yeast and hyphae 0

Fungus Fact

#162: Candida albicans

In opportunistic fungal infections (FFF#161), fungi behave as they normally do, without drastically changing their cell structure or physiology. On the other hand, true fungal pathogens of animals can grow as both yeasts and hyphae. The fungus Candida albicans is somewhere in between these two groups. It normally inhabits healthy skin but can cause infection in people with a weakened immune system. In fact, it is one of the most virulent opportunistic pathogens. However, C. albicans can grow both as a yeast and as hyphae, making it morphologically more similar to true pathogenic fungi. C. albicans causes some of the most common fungal diseases, including: thrush, “yeast infections,” and invasive candidiasis.

Aspergillus sp. conidia 1

Fungus Fact

#161: Opportunistic Fungal Infections

This October, I will be discussing human fungal infections. Although fungi can be extremely problematic for certain species of animals and plants, fungi cause humans relatively few problems. There are roughly 300 species of fungi that cause disease in humans, but the most common ones cause nuisance infections of the skin. About 20-25% of the global population has a fungal skin infection like ringworm, athlete’s foot, and similar diseases. Although annoying, these infections are not very severe. There are a few fungi that cause more severe diseases, but these are much less common. The most dangerous type of fungal infections are the opportunistic infections. These are caused by normally benign fungi that take advantage of unusual conditions, such as when a patient has a weakened immune system.

By walt sturgeon (Mycowalt) [CC BY-SA 3.0], via Wikimedia Commons 0

Fungus Fact

#160: Suillus luteus, the Slippery Jack

Often called the “Slippery Jack,” Suillus luteus is a fall bolete notable for its extremely slimy cap. Although you might think this texture is unsuitable for the table, the Slippery Jack is actually eaten fairly regularly. People who do eat this mushroom must make sure to peel off the upper surface of the cap. This is done for two reasons: the slimy layer does not have a very good texture and contains toxins that may cause some gastrointestinal distress.

mushroom-dyed wool rainbow 5

Fungus Fact

#159: Dyeing with Mushrooms

Natural dyes come from many sources: plants, animals, and even fungi. Historically, lichens were used to achieve certain colors, including purples and reds. Techniques for lichen dying have been around for thousands of years. Surprisingly, using mushrooms to dye fibers was first developed in 1972! The procedure for mushroom dyeing was developed by Miriam C. Rice, who I have previously mentioned as the inventor of mushroom papermaking (FFF#084). The procedure for mushroom dyeing is pretty much the same as when using other natural dyes: treat the fibers with a mordant, cook the fibers with the dye, and rinse the fibers.

Hypomyces chrysospermus 2

Fungus Fact

#158: Hypomyces chrysospermus, the Bolete Eater

Occasionally, you encounter something that has the stature and shape of a bolete but is completely smooth underneath its cap. “What can this be?” you ask. “No crust fungi are this fleshy or have such a well-defined cap and stem.” It turns out that you did find a bolete, only it is being parasitized by another fungus! Hypomyces chrysospermus is a common parasite of all kinds of boletes. It forms a crust that often completely engulfs its host. The “Bolete Eater,” “Bolete Mold,” or “Golden Hypomyces” is easy to identify, thanks to its preference for boletes and its white to yellow color scheme.

Dead Frog 3

Fungus Fact

#157: Chytridiomycosis

Chytridiomycosis is a disease causing precipitous declines in frog and salamander populations on a global scale. There are two fungi responsible for this disease: Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandivorans (Bsal). The former can infect all amphibians while the latter infects only salamanders and newts. Both of these pathogens belong to the fungal phylum Chytridiomycota. Fungi in this phylum (“chytrids”) have a very simple cell structure and produce spores with flagella. Because of this, they can easily swim through water and infect amphibian hosts.

#156: Calvatia gigantea, the Giant Puffball 1

Fungus Fact

#156: Calvatia gigantea, the Giant Puffball

This mushroom certainly lives up to its name!  The largest Calvatia gigantea fruiting body on record was 8ft 8in in diameter and weighed 48 pounds!  Normally, the “Giant Puffball” forms mushrooms much smaller than that.  However, the mushrooms routinely reach sizes of a foot across or larger.  Many could easily be mistaken for abandoned soccer balls from far away.

#155: Microglossum viride, the Green Earth Tongue 0

Fungus Fact

#155: Microglossum viride, the Green Earth Tongue

This is probably one of the most difficult fungi to find in North America. It is not a common mushroom, but its occurrence may be underreported thanks to its small size and green colors.  These traits mean that Microglossum viride is particularly adept at blending in with its mossy surroundings.  However, its unmistakably green coloration means it is very easy to identify the “Green Earth Tongue” once you have found it.