Small Things Considered

A Joyous Note (Amphibian Division)

Gastrotheca riobambae, an Ecuadorian
marsupial frog studied by Del Pino. Source:
Pontificia Universidad Catolica del Ecuador

In 2006, an Ecuadorian investigator, Eugenia Del Pino, was elected to the U. S. National Academy of Sciences. Her extraordinary contributions pertained to frog development, not exactly a microbiological subject. (She was even quoted as saying:  I didn't want to work with bacteria.) Nevertheless, the announcement causes me to celebrate. I spent my youth in Quito, Ecuador's capital, and have a special affection for that city and country. Hers is a singular honor, seldom bestowed on investigators from the developing world. It is not her first such award─another demonstration that exceptional talent cannot be constrained by suboptimal working conditions. The biographical note in a recent issue of PNAS attests to this and can inspire us all.

Crawlies Up My Inner Tubes

I get somewhat squeamish when thinking of bugs crawling up my urinary tract. Perhaps you do too. The story of E. coli ascending the urinary tract, however, turns out to be fascinating, which assuages my dainty feelings.

The Human Urinary Tract. Credit: National Kidney &
Urologic Diseases Information Clearinghouse (NKUDIC)

Space Odyssey, Salmonella Style

It would take a brave person to question a paper signed by 41 authors, especially when they performed an amazing experiment on gene activation in space. In fact, given the difficulties of carrying out such an experiment, any criticism would be downright churlish. Nevertheless...

Credit: Records of the U.S. Information Agency, National Archives.

Do Bacteria Age?

A microcolony of E. coli developing on agar from
three neighboring cells. ASM Microbe Library.
Credit: J. Shapiro and C. Hsu

The question arises: do bacteria get old? Of course they do, their being young immediately after cell division and old when they are about to divide again. But, in a different sense, do they age over many generations? Or, as is commonly assumed, does binary fission obliterate any difference between sibling cells? The question has been studied in detail by Eric Stewart and colleagues, with the surprising answer that conventional wisdom is wrong. There is a difference between the growth rates of  "old" and "new" bacteria. Subtle, but there. This question, and a related one regarding the percentage of viable cells in a growing culture, has been discussed in a highly satisfying manner in a series of posts on John Dennehy's illuminating blog, Evilutionary Biologist. I had a small hand in it, as this repartee reminded me of an unassuming and unpublished experiment I did one hundred years ago (or so it seems).

A Masterpiece of Bacterial Structure

Terry Beveridge of Guelph University died recently. We regret the loss of this outstanding structural microbiologist who made stellar contributions to varied topics such as the structure of the S-layer, the interaction of microbial surfaces with metals and antibiotics, bacterial cell division, Gram stain and its variability, and many more. He was a very fine person, befitting his early training with Bob Murray, a great friend of this blog. I am prompted to honor Terry's memory by recounting an important piece of work he published in 1991. It still has much currency.

Thin-section composite showing cell spacer plugs (A) and an end plug (B).
P, Plug; S, sheath; W, cell wall; AM, amorphous matrix. Bars = 100 nm.
Source: TERRY J. BEVERIDGE et al.(1991) Ultrastructure, Inferred Porosity,
and Gram-Staining Character of Methanospirillum hungatei Filament Termini
Describe a Unique Cell Permeability for This Archaeobacterium.
JOURNAL OF BACTERIOLOGY 173(1):130-140

Fine Literature: Shedding Light on Bacteria

Why some bacteria are bioluminescent is a topic that just won't go away. In an earlier post, we mentioned a proposal for a role of light in the repair of UV-induced DNA damage. In 2005, Eric Stabb wrote a review in Microbe (an ASM magazine) that pleasantly helps in formulating the issues and clarifying the nature of this fascinating phenomenon. We may not have the definitive answers, but Stabb helps us think about the questions.

Structural Grace II

In her autobiography in the 2007 Annual Review of Microbiology, Margarita Salas published an electron micrograph of rare beauty. It shows the DNA of phage ø29 casually coiled around itself, with protein TP (for Terminal Protein) at the two ends. Not only is this a fine demonstration of a specific DNA-protein interaction, but the surprisingly symmetrical spiral of the DNA invites speculation about how it coiled itself so elegantly. Any ideas?

Source: Margarita Salas (2007) 40 Years with Bacteriophage ø29.
Annual Review of Microbiology 61: 1-22.
Photo by José M. Sogo

Golden Nuggets

Copper, uranium, gold, and other metals are mined by bacteria and archaea, and this takes place on an industrial scale. (For two reviews, click here and here.) Consortia of these organisms leach minerals from ores─even low-grade ores─and thus have commercial blessing. This is an old story. Rio Tinto, a river in Southern Spain, has been known since pre-Roman times to be the site of bacterial mineral mining. Newer is the realization that bacteria also do the opposite of leaching, namely they can mineralize various minerals including gold.

John Stone with Gold Mining Pan ca. 1939. Credit: California Gold: Folk Music from the Thirties. Collected by Cowell, Library of Congress

A Shining Mystery

Brucella abortus
(false colored).
Source: Veterinary
Laboratories Agency
(UK)

Who wouldn't agree how enormously gratifying it would be to make ecological sense of every lab finding, to see how the phenomenon being observed fits with the organism's life outside the lab. Sounds easy? Fat chance. Most of the time, we can only make guesses, and there are occasions when even a good guess eludes us. Here is a recent example. Brucella abortus, the agent of brucellosis in livestock and humans, has a light sensor, and the expression of some of its genes are controlled by light. Not being a phototroph and not living most of the time in a lit environment, this alone may be a surprise. But there is more to this.

A Nice Bouquet

"I just came across your blog and wanted to thank you for contributing such a breadth of information regarding many different aspects of microbiology. I'm going to be teaching an advanced microbiology course this spring and I'm excited to be referencing your blog.

Thanks again for spending the time to do this."

Bethany D. Jenkins
University of Rhode Island