Monday, December 31, 2012

Zygosaccharomyces bailii wants to ruin your Snakejuice
We are upon the hour of a new year, which of course means booze! Now, we all know that there will be a medley of alcohols consumed tonight. I am sure that we are also all fully aware that we owe thanks to yeasts, for making that fermentation process so readily available.

But not all yeasts want to help with your intoxication. And in the same way they will spoil your good times, those yeasts are called spoilage yeasts.

One of the widest spread spoilage yeasts, Zygosaccharomyces bailii, is so successful because it has the ability to tolerate a wide range of stressful living conditions (like fermented products.) While many products like wine, mayonnaise, and even pickles, are generally described to be shelf stable; Z. bailii is ready to get all up in there and have a good time. One of the sweet skills that lead this yeast to be successful is that it can metabolize both glucose, and acetic acid (which is generally seen as a stressor/killer of yeasts.)

Zygosaccharomyces bailii wants to ruin your Snakejuice
 A new study published in the December 28 issue of PLOS One seeks to explore the relationship of Z. bailii’s utilization of these substrates and how it manages to grow efficiently when both are present. Does it utilize both in the same metabolic pathways? Or do the two get consumed separate and independent of one another?

The Fate of Acetic Acid during Glucose Co-Metabolism by the Spoilage Yeast Zygosaccharomyces bailii

In order to determine whether Z. bailii grew more efficiently in the presence of just one substrate or the other, the team grew strains in isolated substrates as well as mixed substrates of Acetic Acid and glucose. Throughout the growth cycle they measured the biomass and compared amongst the cultures. The results of this demonstrated a number of things.

When comparing those growth rates  and biomass produced on the isolated substrates to those on the mixed substrate cultures, the team found that a mixed growth medium held a lower growth rate at a pH of 3.0 over either pure substrate. This suggests that with the pH lowered the acetic acid affects efficiency, which is evidence of a need by the cell, to overcome intracellular acidification. This is reinforced by the observation that when grown at a higher pH of 5.0 the decrease isn't evident. A similar difference in growth rate is noticed in the purely acetic acid substrate cultures. However; when grown on a mixed substrate of Glucose and acetic acid, Zygosacharomyces bailii utilizes both the acid and sugar simultaneously. The yeast appears to use each of the substrates individually as both a carbon source and an energy source, showing no effect in the presence of the other. This is significant, because generally speaking the presence of glucose reduces the usage of substandard (energy wise) carbon and energy sources.

By using magnetic resonance spectroscopy and measuring 14C at various pathway steps, the researchers were able to determine that even when glucose is present, acetic acid will act as an additional source of acetyl-CoA during the Krebs Cycle, as well as for lipid biosynthesis. Basically that means Z. Bailii takes a typical environmental stressor and uses it to make extra amounts of the precursors for fueling one of the major energy cycles. And thus, your drink and New Year's Eve Bash are destroyed.

Awesome Researchers:

Rodrigues, F., Sousa, M., Ludovico, P., Santos, H., Côrte-Real, M., & Leão, C. (2012). The Fate of Acetic Acid during Glucose Co-Metabolism by the Spoilage Yeast Zygosaccharomyces bailii PLoS ONE, 7 (12) DOI: 10.1371/journal.pone.0052402

Photo Cred:
DTDT (Own work) [GFDL ( or CC-BY-SA-3.0-2.5-2.0-1.0 (], via Wikimedia Commons

Gif - Ron Swanson of Parks and Recreation via GIFSoup

Friday, December 28, 2012

Fungal Word Friday: Pileipellis

The skin of a mushroom is called the cuticle.
 Russula mustelina with portion of cuticle peeled
away from the cap.

However; there are more specific names for the skin at a microscopic level in accord to what portion of the fruiting body they are located. Pileipellis is the name attributed to the microscopic level of the cuticle on the mushroom cap.

Image of Psilocybe aztecorum pileipellis (Microscopic make up of the cap cuticle.)

Photo Creds: 

Amadej Trnkoczy (amadej) [CC-BY-SA-3.0 (], via Wikimedia Commons

Alan Rockefeller [CC-BY-SA-3.0 (], via Wikimedia Commons

Friday, December 21, 2012

Fungal Word Friday: Coprophilous

Coprophilous is a term used to denote that a fungus grows on dung.

Many fungi that grow on dung must find ways to launch their spores far enough away that they have the potential to be picked up by animals that would not eat near dung. The most famous of these fungi are those in the Pilobolus genera, which launch their spores with the fastest acceleration in the living world.

Pilobolus sp. growing on some poo.
Photo Cred: By 19Adelheid (Own work) [Public domain], via Wikimedia Commons

Friday, December 14, 2012

Fungal Word Friday: Obclavate

Obclavate means shaped like a reversed club. Where the distal part is smaller. In mycology this is often in reference to conidia shape.
Obclavate Conidia of Alternaria sp.

Photo Credit: Ninjatacoshell (Own work) [CC-BY-SA-3.0 ( or GFDL (], via Wikimedia Commons

Friday, December 7, 2012

Mushroom of the Month: Dryad's Saddle

The Dryad's Saddle (Polyporus squamosus) is a bracket fungus that is widely distributed in Asia, Australia, Europe, and North America. This fungus is a fan of both live and dead hardwoods on which it causes white rot disease.

Polyporus squamosus

We will turn again to mushroomexpert to run down a key.
1. Mushroom growing on other mushrooms or the decayed remains of other mushrooms. Mycotrophs
1. Mushroom not growing on other mushrooms. 2

2. Mushroom with gills or pores on its underside. 3
2. Gills and pores absent.

3. Growing shelflike on wood (or, if not, then gills concentric rather than radial); mushroom very tough and leathery, corky, or woody (try tearing it in half); gills or pores tough and hard; cap frequently (but not always) with concentric zones of color.   4 Polypores
3. Not completely as above.

4. Stem present (central or lateral).5
4. Stem absent. [To be developed.]

5. Flesh pale (white, pale pinkish, etc.) when young and fresh.    6 Stemmed, Pale-Fleshed Polyporus
5. Flesh darker than above when fresh and young. [To be developed.]

6. Growing above ground on the wood of trees, stumps, logs, branches, or sticks. 7
6. Growing at the very bases of trees or stumps--or growing terrestrially, from buried roots or without clear association with a tree.

7. Stem black or with a black base. 8
7. Neither stem nor stem base black. 

8. Cap with scales. 9
8. Cap without scales. 

9. Only rarely growing on wood; recorded only from California and the Southwest; scales raised, with sharp edges; stem with white hairs over the blackish portion; mushroom connected through the wood to a large underground mass of tissue (a "sclerotium"). Polyporus tuberaster
9. Always growing on wood; widely distributed but more common east of the Rocky Mountains; scales pressed down, with rounded edges; stem without white hairs; sclerotium absent.         Polyporus squamosus
For more information on this mushroom i present you with the wikipedia page:

Photo Cred: By Appaloosa (photographed by Appaloosa) [GFDL ( or CC-BY-SA-3.0 (], via Wikimedia Commons

Fungal Word Friday: Anthropophilic

Any fungus that preferentially grows on humans rather than other animals or the soil.
Trichophyton tonsurans on plate.
T. tonsurans where it would like to be.
Photo Creds:
By Nathan Reading from Halesowen, UK [CC-BY-2.0 (], via Wikimedia Commons

[GFDL ( or CC-BY-SA-3.0-2.5-2.0-1.0 (], via Wikimedia Commons