Moselio Schaechter


  • The purpose of this blog is to share my appreciation for the width and depth of the microbial activities on this planet. I will emphasize the unusual and the unexpected phenomena for which I have a special fascination... (more)

    For the memoirs of my first 21 years of life, click here.

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« September 2009 | Main | November 2009 »

October 29, 2009

There's Gold in That Thar Periplasm

by Elio

Fortyniners_1_e

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

When thinking of a gold prospector, most of us conjure up a wizened old character leading a mule that carries his pick, gold pan, and rusty coffee pot. Nowadays, think of bacteria instead. Specifically, picture the bacterium Cupriavidus metallidurans (formerly Ralstonia metallidurans), which carries out the biomineralization of gold. It transforms toxic gold compounds into their metallic form via an active mechanism.

The leader of a large international research group working on this subject, Frank Reith of the University of Adelaide, explains: A number of years ago we discovered that the metal-resistant bacterium Cupriavidus metallidurans occurred on gold grains from two sites in Australia. The sites are 3500 km apart, in southern New South Wales and northern Queensland, so when we found the same organism on grains from both sites we thought we were onto something. It made us wonder why these organisms live in this particular environment. The results of this study point to their involvement in the active detoxification of Au complexes leading to formation of gold biominerals.(Science News)

Continue reading "There's Gold in That Thar Periplasm" »

October 28, 2009

Microbial Art

by Elio

Appletree

Apple Tree by Dr. Niall Hamilton of New Zealand. Source.

Curious about what all you can paint using bacteria as your pigments? Use your artistry to inoculate agar plates by design, then wait for the bacteria to grow into colonies in esthetic shapes and colors. To whet your appetite and see what can be done, given appropriate talent, visit Microbial Art at http://www.microbialart.com/ Here you'll find original works grown by several microbiologists of artistic bent.

This website, the creation of T. Ryan Gregory at the University of Guelph, has links to lots of other visual goodies. There's almost no end to them.

October 26, 2009

Mad Dogs and Microbiologists

by William C. Summers

PasteurLabo

Pasteur’s laboratory (around 1885). Source.

Jean-Baptiste watched the powerful dog with unsteady gait approach and then attack a group of six of his friends. He picked up his whip and rushed to meet the animal, only to be savagely bitten on his left hand. In fierce hand-to-hand combat, Jean-Baptiste finally managed to throw the animal to the ground, pinning him to the ground under his knee. With his right hand he forced the dog's jaws apart, sustaining new bites, then used his whip to tie the muzzle of his enemy and finally beat the beast to death with one of his wooden shoes.

Thus it was that Louis Pasteur recounted to his colleagues at the Académie des Sciences in Paris how his heroic patient, Jean-Baptiste Jupille, a 15-year-old shepherd boy from the Jura, came to be exposed to rabies on October 14, 1885. Pasteur was reporting on the success of his treatment of his first rabies patient, Joseph Meister, who was still alive and well more than three months after having been severely bitten by a rabid dog. Meister's survival was considered something of a miracle, because rabies was, and still is, considered a lethal disease in the absence of effective treatment. Young Jupille was treated as Pasteur’s second rabies patient and he, too, survived this heretofore universally fatal disease.

Still, Pasteur had been hesitant to treat Jean-Baptiste because the disease had such a head start on him. From his experimental work on dogs and rabbits, Pasteur and his protégé, Emile Roux, knew that their new treatment was most effective before or very soon after inoculation of the infectious agent. The longer the interval between inoculation and the start of treatment, the less likely the cure. This very early conclusion remained one of the unsolved problems in rabies treatment, at least until very recently.

Continue reading "Mad Dogs and Microbiologists" »

October 22, 2009

Fiddling with Fungi: And the Winner Is…

by Elio

JCS Xylaria longipes 40612

X. longipes. Source.

Late in August of 2008 we promised to update you on the attempts to out-Stradivarius Stradivarius by crafting violins made from wood treated with fungi. Here is the latest news.

Scientists at the Swiss Federal Laboratories for Materials Testing and Research made violins from wood treated with two different fungi: Physisporinus vitreus for the spruce top plate and Xylaria longipes (aka Dead Man's Fingers) for the sycamore bottom plate. The treatment lasted six or nine months, by which time the wood had become covered with a fuzzy growth of mycelium.

Continue reading "Fiddling with Fungi: And the Winner Is… " »

October 19, 2009

Small Friends of Fungi

This article first appeared in the splendid Cornell Mushroom Blog. Reading it, we were jolted into realizing that we had a distorted view of the living world, no less. Like most people, we believed that in natural habitats, some animals eat plants, those animals are eaten by predators, and that's about it. We thank Bob Mesibov for setting us straight. We are delighted to share his insights with you by reproducing his article here, with permission from him and from Kathie Hodge, editor and blogificator of the Cornell Mushroom Blog.

by Bob Mesibov

Narceus

The millipede Narceus americanus photographed by
Kent Loeffler, copyright Cornell University. You can
find this borescopic image among the many in the
book Beneath Notice: Adventures with a Borescope
by Kent Loeffler, with "Fungal Outbursts" by Kathie
Hodges.

If you studied the traditional sort of biology, you're probably carrying around an unfortunate prejudice.

You see terrestrial habitats as a simplified nutrients-and-energy pyramid. At the bottom are green plants, feeding on sunlight, carbon dioxide and soil water and minerals. Next layer up on the pyramid is the herbivore mob: leaf and stem eaters, sapsuckers, root nibblers, seed and fruit gobblers. Above these green feeders are a couple of layers of predators. And that about sums up the world, right?

Wrong. That's only part of the world, and a small, very specialised part of it, too.

Continue reading "Small Friends of Fungi " »

October 15, 2009

Talmudic Question #54

Some believe that the extent of anaerobic respiration on Earth is usually underestimated. What is your guess for the proportion of biogenic CO2 that is made by this mechanism?

October 12, 2009

Getting a Handle on Cell Organization

by Franklin M. Harold

Mitotic_spindle

Mitotic spindle of a human cell: microtubules in green,
chromosomes in blue, centrosomes in red. Source.

Structural organization is one of the most conspicuous features of cells, and possibly the most elusive. No one really doubts that that cell functions commonly require that the right molecules be in the right place at the right time; or that spatial organization is what distinguishes a living cell from a soup of its molecular constituents. But the tradition that has dominated biological research for the past century mandates a focus on the molecules, and so our first step is commonly to grind the exquisite architecture of the living cell into a pulp. Few molecular scientists have asked whether anything irretrievable is lost by this brutal routine. Such questions as how molecules find their proper place in a framework orders of magnitude larger, or how spatial order is transmitted from one generation to the next, have been largely neglected until recently.

Two current and quite excellent short reviews afford an entry into the wilderness. Eric Karsenti takes an historical approach to the role of self-organization in creating order on the cellular scale. The physical principles are arcane, but some aspects are actually quite familiar. We have known for half a century that supra-molecular complexes often arise by self-assembly, without any input of either information or energy; examples include lipid bilayer membranes, ribosomes, microtubules, S-layers and virus particles. But the scope of self-organization has been greatly enlarged in recent years by the discovery that an array of dynamic structures can be generated in the presence of an energy source, usually ATP or GTP. The mitotic spindle of eukaryotes has been identified as a self-organizing machine, the endomembrane system may be another. Like self-assembly, self-construction (my term) requires no external source of information, but it does entail continual energy consumption. In a complementary article, Allen Liu and Daniel Fletcher survey a selection of efforts to reconstitute cellular functions in simplified systems, starting with cell-free extracts or purified proteins. Ingenious experimenters have managed to reconstitute the essentials of actin-based motility, membrane protrusion, the oscillatory system that localizes the midpoint of bacterial cells, and now also the contraction of the Z-ring. Though much remains to be learned, it is safe to conclude that the lower levels of cellular order, at least, are products of pure chemistry: they arise by interactions among the molecular constituents in ways that require the cell as a whole to supply energy and a permissive environment, but no spatial instructions.

This is excellent science, which takes us some way towards bridging the gulf between nanometer-sized molecules and cells in the range from micrometers to millimeters. It also extends the genome’s reach deep into cellular structure. In a self-organizing system, the “instructions” must be wholly inherent in the molecular parts, and ultimately derive from the corresponding genes. It is the genome that specifies the architecture of the mitotic spindle, not explicitly but indirectly: the form and even functions of the spindle are implied in the structure of the spindle proteins, and in their interactions. And if the spindle can be envisaged as a creature of self-organization, why not the entire cell? Yes, indeed─but as we ascend the hierarchy of biological organization, the meaning assigned to self-organization and its underlying mechanisms undergo significant changes. Cells do not construct themselves from pre-fabricated standard parts; instead, they grow. And that mode of self-organization is not purely chemical, for it must produce parts that have biological functions, performed in the service of a larger entity that can compete and thrive in the wide world (discussed here).

Continue reading "Getting a Handle on Cell Organization" »

October 08, 2009

Of Terms in Biology: Neuston

by Merry

Water_strider

A water strider. Surely handsome, albeit not microbial.
Source.

When I stumbled across the term bacterioneuston, I discovered a whole new world where the air meets the sea. I found that marine neuston had long been used to refer to the diverse flora and fauna inhabiting the topmost 5 cm of the oceans—a distinctly different assemblage than found in the waters below. This broad grouping had been further subdivided. Floating organisms, such as Physalia, the Portuguese Man o' War, make up the pleuston (the small organisms floating on or near the surface of a body of water, from the Greek pleustikos, fit for sailing). The 40-some species of water striders are part of the epineuston (the organisms living in the air on the surface film of a body of water). Just beneath them, living immediately below the surface film, are the organisms of the hyponeuston. There are no hard and fast lines here. A diving epineustonic water strider finds itself briefly a hyponeuston. The planktohyponeuston gather near the surface at night but spend their days below. And, of course, the plankton float or drift throughout the rest of the water column. (For these neustonic terms and more, click here.)

Continue reading "Of Terms in Biology: Neuston" »

October 05, 2009

All for One, and One for All!

by Mark Martin

Panic

Panic grass growing well at a soil temperature
of over 50 °C (123 °F). Source.

When I recently attended the Sixth International Symbiosis Society Congress in Madison, Wisconsin, I was awed by the fascinating forms that symbiotic relationships take among diverse organisms. One talk that particularly intrigued me was from the laboratory of Marilyn Roossinck of the Samuel Roberts Nobel Foundation in Oklahoma, which described the mutualistic relationship between a virus, an endophytic fungus, a monocot, and elevated temperatures in geothermal soils. It also made me consider how readily we seem to associate the word "virus" with pathogenic associations, when nature is often far more subtle when it comes to mutualistic partnerships.

The story began in 2002 when it was found that a type of grass growing in the geothermal zones of Yellowstone National Park—panic grass, Dichanthelium lanuginosum—was able to survive intermittent high temperatures in geothermal soils (up to 65 °C.) due to its association with an endophytic fungus, Curvularia protuberata. The fungus is essential to the plant's ability to tolerate temperatures that are lethal to the non-colonized plant. Panic grass, incidentally, has nothing to do with botanical phobias; instead, the name derives from the Latin panicum, referring to foxtail millet.

Continue reading "All for One, and One for All!" »

October 01, 2009

Of Terms in Biology: Planktonic

by Elio

The image of a diatom chain previously displayed here was used without permission of the photographer and has been removed. If any blog visitors have downloaded that image, they should be aware that it is under copyright and that permission and payment of a fee is required for its use. Our apologies to the photographer.

800px-Diatoms_PhC

Phase contrast image of diatoms. Source.

The word planktonic is widely used in microbiology for organisms that are floating in bodies of water. It may be worthwhile to ponder its meaning. According to Wikipedia: plankton consist of any drifting organisms (animals, plants, archaea, or bacteria) that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. So, what does pelagic mean? Wiktionary says: Living in the open sea rather than in coastal or inland waters. Clearly, microbiologists use the term planktonic without the “pelagic” restriction, and include any body of water, even that in a test tube. The word plankton is derived from the Greek word πλαγκτος ("planktos"), meaning wanderer or drifter (thus also related to planet).

What is the antonym of planktonic? Sessile comes to mind (i.e., permanently attached or established, not free to move about). Its etymology? From the Latin sessilis, from sessus, past participle of sedēre, to sit. But attached or clinging would do as well. Not relevant here but of linguistic interest, the antonym of sessile is vagile, having freedom to move about. I had never heard of it. I stopped being vagile years ago.

If sessile does not appeal to you, perhaps adhering would do. Or maybe we should invent a new term. How about biofilmic or biofilmatic? Want to vote it in or out? Let us know.

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  • We welcome readers to answer queries and comment on our musings. To leave a comment or view others, remarks, click the "Comments" link in red following each blog post. We also occasionally publish guest blog posts from microbiologists, students, and others with a relevant story to share. If you are interested in authoring an article, please email us at elios179 at gmail dot com.

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