Small Things Considered

Talmudic Question #29

by Bob Murray

What is the life expectancy for the descendants of a single bacterial cell under ideal or stressful conditions?

Microbial Philosophy

For anyone interested in the philosophy of microbiology (and who shouldn’t be?), the Centre for Genomics in Society of the University of Exeter (UK) sponsors a website called Dimensions of Microbiology. There you will find all sorts of material relevant to this way of looking at microbiology. For instance, there are links to a Philosophical and Social Dimensions of Microbiology Workshop, to papers on the Philosophy of Bacterial Systematics/Species, to a series of papers on Towards a Philosophy of Microbiology, and much more. This is a must for those interested in looking beyond the rim of a Petri dish.

Electrifying Bacteria!

by members of the Integrative Microbiology graduate course (winter quarter 2008), University of California at San Diego/San Diego State University*

EM image showing the photosynthetic
cyanobacterium Synechocystis PCC 6803
making electricity using light (energy
source) and water (electron source) in
a microbial fuel cell. Courtesy of Yuri
Gorby, J .C. Venter Institute.

Many a live wire would be a dead one except for his connections.
                  Wilson Mizner, Playwright

Imagine that there is an alien—on some distant planet—who can reach out with a living appendage of its own and use byproducts of its own metabolism to transfer an electric current outside of its own body. If you think that is bizarre, look no further than our planet—and think small. Metal-reducing bacteria do exactly that. If a little convincing was necessary to think that bacteria are the most exciting and versatile creatures in this world, then their ability to produce an electric current might just do it.

Getting CRISPR

by Merry

When you're outnumbered five or ten to one, strategy counts. Bacteria and archaea are master strategists, thriving despite the omnipresent hordes of phage. For some time, it has been known that prokaryotic cells have ploys for blocking phage adsorption, preventing DNA injection, recognizing and cleaving the incoming DNA, and otherwise aborting the infection. Recently, another potent─and likely very ancient─mechanism of defense has been discovered.

Fine Reading: The Uncharted Microbial World

The American Academy of Microbiology has just announced the release of its newest colloquium report, The Uncharted Microbial World: Microbes and their Activities in the Environment. This report, based on a series of discussions by experts in the field of microbiology, explores the mysteries of the microbial world.

It makes for very good reading

Why Have Lectures?

Recently, I wrote an article called In Defense of the Lecture. It appeared in Resonance, a science education journal of the Indian Academy of Sciences. If you care to know what this is about, here is the first paragraph from the article.

When it comes to teaching, everyone is an expert, so why not me? Any amount of experience, large or small, guarantees that one will hold strong views. I am no exception. In the course of over 50 years, perhaps 20,000 students have had to listen to me, the majority of whom I probably bored, a few whom I may have stimulated. I have no formal training in pedagogy. With these dubious credentials, let me make a single point: Lectures are a vital aspect of university teaching.

Archaeal Web

A venting black smoker emitting sulfide-rich
fluids. Courtesy of University of Washington

Deep sea hydrothermal vents are characterized by steep physical and chemical gradients and by the presence of unusual and fascinating life forms. Varied organisms grow there: giant tube worms that exploit the metabolism of sulfide-oxidizing bacteria, clams, crabs, shrimps, and more. These like their water tepid. But some archaea prefer the hotter neighborhood near the vents that emit water at around 400°C. These microbes are hyperthermophiles, thriving at temperatures around 100°C. Many have a specialized life style, and one them, Pyrodictium, is particularly interesting.

Fine Reading: The Origins of Photosythesizers

The discovery of bacterial fossils dating back to the early days of the Earth is among the most stirring facets of microbiology. I hadn’t assumed that the subject had been exhausted, but I did think that the basic facts regarding early photosynthetic cyanobacteria had been established. Not exactly so, as I have learned by reading the review written by Robert Riding of Evolution of Primary Producers in the Sea by P. G. Falkowski and A. H. Knoll. In a few words, Riding makes it clear that we have an incomplete and uncertain knowledge of the development of photosynthetic organisms in the oceans.

Joshua Lederberg and the "Cellularity" of Bacteria

Joshua Lederberg died recently. His is a revered name among our older readers, and we assume that many younger ones also know of him. But just in case, let us mention some of what made him a giant in modern biology. He is best known for finding that bacteria have sex, that is that they can undergo cell-to-cell conjugation. He then discovered (with Norton Zinder, a graduate student) that genes can also be exchanged via phages: transduction. Thus Lederberg discovered two of the three major mechanisms for gene transfer in bacteria. The third, transformation by naked DNA, had already been discovered, or else—who knows?—he might have found that one, too. He then entered the fray related to the origin of mutations. For this purpose, he invented, together with his wife Esther, the replica plating technique, which allowed him to demonstrate that mutations were spontaneous and random, not induced by something in the environment. He did this by comparing a mutant colony identified on a replica plate with the corresponding colony on the master plate, and showing that they both had the same properties. That ended the argument, at least for the time.

These accomplishments place Lederberg among the great biologists of all times. However, Lederberg did much more.

Talmudic Question #28

The eukaryotic nuclear membrane is something of a mysterious structure and its origins are the subject of much debate. It would be interesting to hear a microbiological view on the question: why is there a nuclear membrane?