Tagged: yeast

single-celled fungi


#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

#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

#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.

Fungi in the News Image 0

Mycology News: April to June 2016

Fungi appear in the news with surprising frequency. However, many of those stories do not provide any new information. Below is a summary of what we’ve learned about fungi from November 2016 Through February 2017. Read below to learn about: mycorrhizas, A. bisporus engineering, fungal evolution, psilocybin research, fungal concerns in medicine, rock-eating fungi, and more! Visit the associated links to get the full story.

#131: Class Ustilaginomycetes, Smut Fungi 0

#131: Class Ustilaginomycetes, Smut Fungi

These fungi are obligate plant pathogens with life cycles similar to the rust fungi. Thankfully, the smut fungi have much simpler life cycles: only one host and only two spore types.  To make matters easier, smut fungi only infect flowering plants (angiosperms), with just five known exceptions out of the over 1,400 described species.  Wondering about their common name?  Although the word “smut” has come to mean “something obscene,” it originally meant “dirt” or “excrement.”  Smut fungi produce copious amounts of powdery, black spores, which look like dirt en masse.  “Smutted wheat,” therefore, is wheat that has had its seeds replaced by the dirt-like spores of a smut fungus.

#059: <em>Tremella mesenterica</em>, Witch’s Butter 1

#059: Tremella mesenterica, Witch’s Butter

Legend has it that witches use this fungus to cast hexes. When this fungus appears on your gate or door, you have certainly been the victim of a witch’s evil spell.  The only way to counter the hex is to pierce the fungus with straight pins, allowing the inner juices to drain and thus killing the fungus and the spell.  Unfortunately for those who believe this superstition, this method probably doesn’t work too well for two reasons.  First, the mushroom is specifically designed to survive repeated dehydration and rehydration.  Second, the main body of the fungus is still living inside the wood.  Unless you replace the wood you will probably find the mushroom repeatedly fruiting from the same place.

#048: Mushroom Morphology: Jelly Fungi 0

#048: Mushroom Morphology: Jelly Fungi

As you might guess, jelly fungi are distinguished by their gelatinous consistency. Their external appearance varies widely, so their texture is the only macroscopic feature that defines this group.  These fungi are placed within the phylum Basidiomycota, but they produce basidia (spore-bearing structures) unlike those of most other basidiomycetes (for more on basidia see FFF#013).  Because of this, they are often placed in the artificial group of fungi called heterobasidiomycetes.  The heterobasidiomycetes also include rusts and smuts, which do not form mushrooms.  Jelly fungi produce three different variations on the normal basidium (holobasidium) morphology.  Holobasidia have a bulbous, undivided base topped with spore-bearing steritmata.  The first variaition on this model is the cruciate basidium.  Cruciate basidia have a bulbous base divided into four cells by septa (cell walls).  The septa are at right angles to one another, making a cross shape when the basidium is viewed from above.  A good...

#025: Production of Soy Sauce 0

#025: Production of Soy Sauce

There are two ways to make soy sauce: the traditional brewing process or the modern chemical hydrolysis process. In short, the traditional process involves the fermentation of soybeans and wheat by fungi and some bacteria.  The hydrolysis process extracts the amino acids from soy and adds other ingredients to create a liquid similar to soy sauce.

#024: Fungi in the Production of Chocolate 1

#024: Fungi in the Production of Chocolate

Along with red roses and cheesy cards, chocolate is one of the common Valentine’s Day gifts. So on this day when heart-shaped boxes of chocolates are a common sight, I thought you might like to learn a little about how chocolate gets from the cocoa beans to the cloying boxes (be thankful I didn’t decide to discuss fungal diseases you can get from roses).  You probably already know that chocolate comes from the seeds of the cacao tree, Theobroma cacao.  The first way in which fungi allow for the production of chocolate is by helping the cacao tree to grow.  In order to get nutrients required for growth, all trees participate in mutualistic relationships with fungi called mycorrhizae.  There are a number of types of mycorrhizae, but Theobroma cacao only forms endomycorrhize.  In these mycorrhize, fungi in the phylum Glomeromycota penetrate the root cells of the tree and form specialized...

#023: <em>Tremella fuciformis</em>, the Snow Fungus 1

#023: Tremella fuciformis, the Snow Fungus

This beautiful jelly mushroom also goes by a variety of other common names, including: silver ear fungus, white ear fungus, and white jelly fungus. The fungus fruits from decaying wood and produces white, translucent mushrooms that have a gelatinous consistency.  Its name seems to come from its white color and roughly snowball-shaped fruiting bodies.  Although, if you ask me, its name was probably also inspired by its “graceful lobes,”* which look somewhat like large, squishy points on a snowflake.  The snow fungus’s range is tropical to subtropical, but it can apparently be found in the United States at least as far north as Indiana.   Despite its name, you will not find this mushroom poking out of snow-covered branches.  The mushroom prefers to fruit in the summer and fall, so if you want to see this fungus for yourself you’ll either have to wait half a year or visit the mushroom...