Small Things Considered

The King of the Fungi

This is the second of three installments celebrating the Week of the Fungi on STC.

by Elio

A basidiocarp (fruiting body) of Fomitiporia ellipsoidea.
(Do not try to flip it over. It is in the correct orientation.)
Source.

Small things are not being considered here. Au contraire, I'm reporting on the largest fungus known, if by 'fungus' you mean the fruiting body of the organism. The reason for making this distinction is that a fungal mycelium can reach humongous proportions. The hyphae of a kind of oyster mushroom, Armillaria ostoyae, growing in northeastern Oregon covered some 10 km² and were nearly 9000 years old.

What I have in mind here is the finding on southern China’s Hainan Island of a gigantic fruiting body of a bracket fungus or polypore, Fomitiporia ellipsoidea. This gargantua was a tad over 10 meters long, almost 90 cm wide, and about 5 cm thick (picture half the length of a bowling alley). Its weight was estimated to be between 400 and 500 kg. It was found in a virgin forest where it adorned the underside of the large fallen trunk of an oak tree (Cyclobalanopsis patelliformis). In the words of a fellow blogger who writes Real Monstrosities: ….that's a big shelf. Maybe even a bed. A long bed upon which about 5 people could sleep in single file. If they wanted to….. It's estimated to be around 20 years old, contain about 450 million spores and weigh about half a tonne. So definitely sleep on it and not under it.

Fungi That Spit Like Baseball Players

This is the fourth annual Week of the Fungi on STC, a sporadic undertaking. It is our way to hail the start of the fall mushroom collecting season in parts of our home territory (the northern hemisphere).

by Gemma Reguera

Although I was a tomboy as a child, I never had the stomach for spitting competitions. But that changed recently when I read an article by Nik Money and collaborators about spitting competitions among fungi. Yes, you heard me right. Some fungi spit, and they do so with amazing precision and speed. It has been long known that some fungi in the Ascomycota and Zygomycota use squirt gun mechanisms to launch their spores. But the speeds and distances that some of them can achieve have only recently been measured with precision, thanks to high speed video capture microscopy.

One group of fungi, the so-called coprophilous (which literally means 'dung-loving'), have mastered this technique and can launch spores at speeds of 4-21 meters per second! The gold medal in acceleration goes to Ascobolus immersus, which sets the record at 1,800,000 m s^–2. Such acceleration, the authors note, is the fastest recorded flight in nature. To put this number in context, a bullet leaving the muzzle of a rifle barrel approximately 0.9 m long at a speed of 600 m s^–1 will reach an acceleration of 200,000 m s^–2. The record holder for distance is Pilobolus kleinii. This fungus makes some sexy-looking fruiting bodies to propagate its spores and spits like a baseball player. Not surprisingly, it already caught the attention of Elio in two earlier postings (click here and here). Their sporangia (aka individual spores wrapped in a protective enclosure) can land as far as 2.5 meters away from the tip of the sporangiophore (aka the fungal squirt gun). Now, keep in mind that the Pilobolus fruiting body is not even a twentieth of an inch tall!

Talmudic Question #78

Why are there so many species of microbes on earth?

Going Next Door Without Getting Your Feet Wet

by Elio

Thin section of a Listeria-infected macro-
phage. A single Listeria is located at the
tip of a projection from the macrophage
cell surface and behind it a long filamen-
tous tail composed of actin fibers. Source.

Intracellular life has its perks. Inside host cells, bacteria are protected from neutrophils, complement, antibodies, some antibiotics, and the other unpleasant things floating around in tissue fluids. In addition, here they have access to ample food. But there is a catch, namely how to infect other cells and other hosts.

Intracellular life has ancient and distinguished origins. When unicellular eukaryotes first arose, not only did they arise because someone (whoever it was) ingested a prokaryotic cell, but soon thereafter the emerging protists must have learned to go after the abundant food microbial around them. The prey, in turn learned to cope with this and to survive inside the predator cells, something some bacteria do successfully to this very day. Consider how these overcome the destructive forces of phagocytes and other cells. The repertoire of ways they do it is impressive indeed. Of course, not all bacteria live intracellularly, but all viruses must do so at some stage, so this subject is old hat to virologists.

How to Improve Vaccines (or Not), 1912 Style

by Elio

London’s Lister Institute, where Rowland
worked.

By accident, I ran into a paper by an illustrious early British microbiologist, Sydney Rowland, on how to improve (or not) a vaccine. He picked on a claim by one of Metchnikoff’s student, the Russian scientist Alexandre Besredka working at the Pasteur Institute, that a vaccine against the plague bacillus could be made less toxic by treating it with antiserum against the organism. I was surprised that this matter, how to make vaccines safer, was being tackled experimentally so soon after bacterial vaccines started to be developed. And, for some, the same question remains even today.

And We Thought We Knew What CRISPRs Do!

by Merry

…these findings lead us to assert that each CRISPR region should not be assumed to have a role in resistance to phage infection until such a conclusion is experimentally validated. (Source.)

A biofilm microcolony formed by P. aeruginosa PA14
carrying GFP and cultivated in a flow chamber under
continuous culture conditions. Source.

Imagine that you have been growing Pseudomonas aeruginosa strain PA14 in your lab for some time, studying biofilm formation among other things. A student in your lab isolates a phage, dubbed DMS3, that mediates generalized transduction between this and other P. aeruginosa strains. Oddly, this strain, when lysogenized by DMS3, no longer forms biofilms or swarms, both group behaviors. Odd indeed. This is what actually happened in the O'Toole lab at Dartmouth, and this ocurrence led these researchers to the discovery of a new function for CRISPRs. (For an introduction to CRISPRs, see our two earlier posts here and here. For a recent commentary on several papers from the O'Toole lab, see here.)

Fine Reading: Microbial Genomics and Infectious Diseases

by Elio

Would you like to read a concise and well-written review about how genomics has influenced our understanding of infectious diseases? Click here for a satisfying account by David Relman, one of the leading contributors to this field.

After summarizing the dizzying accelerating pace at which complete genome sequences are being acquiredeukaryotic, viral, bacterial, archaeal—Relman discusses how microbial genomic diversity impacts on health and disease, as illustrated by concepts such as the pangenome, genome reduction, genomic islands, CRISPR loci, and others. We read about the evolution of pathogens such as the plague bacillus, including its origin between 2600 and 28,000 years ago in China, and that the common ancestor of all the strains in the USA today probably arrived in San Francisco in 1899. We learn that comparing genomic sequences of Helicobacter pylori strains has been used to determine the timing and direction of human migrations, and that Vibrio cholerae traveled, with human help, from South Asia to Haiti.

Some Like it Cold

by S. Marvin Friedman

The leading edge of a seasonal streamflow, McMurdo
Dry Valleys, Antarctica. Source.

About 70% of Earth’s surface is ocean. In all of them, the temperature at depths of 1000 meters or more is a constant 4 °C, constituting a vast environment populated by a diverse group of psychrophilic (“cold-loving”) microorganisms. Much of terra firma also lies in the realm of the psychrophiles: more than 20% of all soils are permafrost. Scattered about are a variety of other specialized psychrophilic environments, including cryopegs (saltwater pockets within permafrost at –10 °C that have remained liquid for 10,000 years), Antarctic dry valleys, liquid brine veins among sea-ice crystals, and cryoconite holes on the surface of glaciers. Thus psychrophiles may be the most abundant extremophiles on the planet. Yet research on these fascinating microbes has lagged behind studies on thermophiles (“heat-loving”) and halophiles (“salt-loving”).

A Microbe By Any Other Name Would Smell As Sweet…

by Mark Martin

Source.

It has long been known that the sense of smell can evoke the richest memories. Oliver Wendell Holmes wrote: Memories, imagination, old sentiments, and associations are more readily reached through the sense of smell than through any other channel. How does this relate to microbiology? One of the most common complaints from students new to a microbiology lab is that “bacteria smell bad.” (I usually remind them to include the archaea in their eukaryocentric judgmentalism.) But odors—sweet or not—are due to volatile chemicals and can be a form of information, revealing metabolic characteristics and conveying subtle signals between different organisms.

The Janus Bug

by Elio

A paradox, a paradox,
A most ingenious paradox.
(The Pirates of Penzance by Gilbert and Sullivan)

If you wonder what I do with myself when I'm not blogging, well I'll tell you. Among other things, I participate in an ASM-sponsored podcast called This Week In Microbiology (TWIM). It’s posted every two weeks and is easily accessible by clicking here or going to the MicrobeWorld home page. Under the leadership of Columbia University’s podcaster extraordinaire Vincent Racaniello, we sit before our computers and schmooze away about a couple of papers that caught our fancy. Recently, one of the podcasters, Margaret McFall-Ngai, went over a paper with the puzzling title Helicobacter pylori infection prevents allergic asthma in mouse models through the induction of regulatory T cells. You see why this caught Margaret’s attention. Helicobacter and asthma? A bacterium that lives in the stomach has an effect on the respiratory tract? Makes you wonder.