Klebsiella sp. are flagellum-less, rod-shaped, Gram-negative bacteria. The Gram state of a bacterium has to do with the  properties of its outer coating; Gram-positive bacteria have a membrane surmounted by a thick outer wall made of peptidoglycan that readily takes up purple Gram stain, while Gram-negative bacteria have a thin peptidoglycan cell wall sandwiched between inner and outer membranes. Knowing the Gram-state of bacteria helps microbiologists sort out what kind of bacteria they might be dealing with. That’s helpful, as you can imagine, when many of your subjects are simple balls (cocci) or rods (bacilli) that look more or less the same.

The funny name comes from a 19th century German microbiologist named Edwin Klebs. The group is in the enteric bacteria, which itself is within the Gamma-purple bacteria. Misleadingly, many purple bacteria are not purple. But they are bacteria. Tricky, I know. That’s probably why the group seems to have acquired a new name: Proteobacteria. See if you can find it on the bacterial family shrub.

As implied by the term enteric bacteria, many are found in the gut of animals, but many others roam wild and free. Like Klebsiella, they’re all Gram-negative rods, but some do have flagella. Enterobacteria contain some famous names indeed: Escherichia, Shigella(a maker of dysentery), Salmonella, Proteus, Klebsiella, Enterobacter, Erwinia(a plant pathogen that causes fire blight in apples and pears and soft rots in vegetable crispers around the world), and Yersinia, one species of which (Y. pestis) made it big as bubonic plague (aka The Black Death). There are others, too. Though Klebsiellas are sometimes human pathogens, some strains live happily in your gut or on your skin, and many others thrive in the environment and may never see a human their entire lives.

There are presently about seven species of Klebsiella known, and they are becoming important as hospital-acquired (nosocomial) infections. Now we don’t know what species was in the tobacco the researchers studied — they only narrowed it to genus with their genetic screens. Perhaps many species in this genus were present. But take note of the final sentence from this WebMD article about Klebsiella pneumoniae:

Infection with Klebsiella organisms occurs in the lungs, where they cause destructive changes. Necrosis, inflammation, and hemorrhage occur within lung tissue, sometimes producing a thick, bloody, mucoid sputum described as currant jelly sputum. The illness typically affects middle-aged and older men with debilitating diseases such as alcoholism, diabetes, or chronic bronchopulmonary disease. This patient population is believed to have impaired respiratory host defenses. The organisms gain access after the host aspirates colonizing oropharyngeal microbes into the lower respiratory tract.

Campylobacter "twisted bacterium" sp. I need quotes around my middle name. Note the stringy flagella. U.S. Agricultural Research Service

Not long after I became a health and environment reporter in Wyoming, I was assigned to cover a smokeless tobacco talk given by a scientist from the Mayo Clinic.

Smokeless tobacco (aka moist tobacco,  chewing tobacco, and spit tobacco), he said among other points, supported huge populations of live bacteria.

That was surprising to me. I’d never thought about it before, but it did make sense. The tobacco companies don’t exactly autoclave their product.

Since it was my job to report on the talk, I reported that the substance was “teeming with bacteria”, a statement I felt was amply supported by the evidence presented by this guy.

The next day I got a call from a scientist at a state university in the south. He said he was calling to correct what he claimed were the inaccuracies in my story. He then proceeded to enumerate my alleged errors. I clearly remember him singling out the “teeming bacteria” statement.

“Come on,” he said.

For those of you not in the United States, the Mayo Clinic is one of the top, if not the top, medical centers in the country. And though the Mayo Clinic scientist backed up my reporting on his talk when I subsequently called (and the story was just about his talk — not an attempt at a broader survey of the science, even if the southern scientist’s points had been backed up by a broader literature), I felt stung, to be sure. The Gulf Coast scientist even went so far as to send me some of his papers supposedly disproving what I’d written. It was all rather odd. I ask you, why would a scientist at a university 1,000 miles away go out of his way to call a reporter at a circulation 18,000 paper in Wyoming to correct alleged errors that in no way mentioned his research? How would he even know about the story?

Well, guess what? It turns out that not only is smokeless tobacco teeming with live bacteria, so are dry cigarettes, according to a recent article in Science News (see also here for an earlier article). Scientists have found genetic markers for hundreds of species in cigarettes, and have cultured several of them out of packages purchased off the shelf.

When cultured with blood, some of these bacteria can digest it. And as the article points out, scientists have long known smokers have higher rates of lung infection. Doctors always assumed that was due to immune system suppression. But inoculating your lungs with bacteria or their spores several times a day probably doesn’t help.

In retrospect, it’s not surprising. You take leaves. You hang them up in a moist, dark, warm place (a tobacco barn). You wait. In plant pathology, we called this a moist chamber*. It’s how we coaxed fungi to fruit so we could grab their spores for pure culture. Bacteria seem to like the treatment too: scientists found Campylobacter, Clostridium, Corynebacterium, Klebsiella, Staphylococcus, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Escherischia coli, and Bacillus subtilis signatures in cigarette tobacco, according to the Science News article. Not only is this a who’s who of the pathogenic human bacteria world (although is should be noted many species in these genera are not pathogens under ordinary circumstances), these and other bacteria are responsible for producing the most potent carcinogens in cigarette smoke — nitrosamines — when they start chowing down on tobacco leaves. Nor is this the first time cigarettes were found to be hosting . . . er . . . organisms. Cigarettes are often contaminated with plant viruses too. Though entirely harmless to humans, it’s been known for years that people who’ve handled cigarette tobacco can transmit  tobacco mosaic virus.

Now don’t get me wrong — the presence of some bacteria is no reason not to eat or drink a food. Trust me, practically everything you put in your mouth has bacteria in it or on it. Even freshly cooked food probably has a few bacteria or fungal spores settle on it between the pot and your plate. And we purposely introduce billions of “good” bacteria and fungi into food all the time. If you’ve been reading this blog long enough, you know I’d be just as likely to say yogurt, your kitchen sponge, and your mouth are teeming with bacteria (which they are). This story does make me wonder, however, if tea leaves experience something similar to tobacco leaves during processing. Does anyone know? But you don’t smoke tea, and the products of bacterial action on yogurt and tea leaves don’t give people cancer. Tobacco bacteria do.

Next time: a closer look at Klebsiella.

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*Now that I think about it, I think we used grow lights over most of our moist chambers. But I don’t think dark would necessarily discourage fungi.

Lichens(?) and bacteria coat the interior of a lava tube in Hawaii. http://www.flickr.com/photos/lrargerich/ / CC BY 2.0

Life on Earth is everywhere, from pores in rocks miles beneath the surface to tiny cloud particles floating high above. Here’s another example of life turning up in a spot we’d not previously suspected: cave mineral deposits. Turns out the colorful encrustations are sometimes raw bacterial sewage. Pretty sewage, though!

Cave bacteria are often actinomycetes, which were so named because they actually branch (yes, some bacteria can branch!) and make spores similar to fungi. They’re also part of the crowd responsible for that wonderful earthy/cavey smell I mentioned a few posts ago. Actinomycetes are great at making competing-bacteria repellent, aka antibiotics. You might have heard of a few: actinomycin and streptomycin.

This came out in November but I’d been saving this slide show for a fun Friday eye-candy treat. Enjoy!

Punk rockers are clearly dinoflagellate posers. Is it just me or does (a) appear to be a member of the House Harkonnen? Dinoflagellate micro-plankton of Atlantic tropical waters. P. 75. In: "Aus den Tiefen des Weltmeeres" by Carl Chun, 1903. NOAA Photo Library.

Most people have only seen plankton in crappy, fuzzy photos in college textbooks, if they’ve seen it at all. If you have heard of it, it’s probably in the context of the stuff baleen whales eat, and that’s about it. I personally was lucky enough to see an entire jar of the delicacy when I visited the Smithsonian’s Sant Ocean Hall last fall. It looked a lot like the larvae of the neural parasites that took over the brains of the Federation’s top brass in the first season of Star Trek: TNG. Mmmm, mmmm good!

Plankton is not a taxonomic/phylogenetic group like most of the things I write about on this blog. Plankton instead refers to any sea creatures that drift. That can include things as large as jellyfish, but typically plankton are much smaller and include things as small as the bacteria, archaea, and viruses with which the oceans teem. The phytoplankton, or photosynthesizing component, are responsible for half of the oxygen you breathe.

Well, someone’s finally taken some skillful, beautiful pictures of the plankton and they’ve gone on display at the London Zoo in honor of the Royal Society’s 350th Anniversary (Dang! That Society’s been around over 100 years longer than my country!). Over at the BBC there is a don’t-miss slide show of the exhibit, narrated by the scientist photographer, Dr. Richard Kirby. Let me repeat that: DON’T MISS THIS SLIDE SHOW.

You’ll get to see how evolution has taken body plans on some interesting trips, as larvae that retain ancestral forms metamorphose into sea creatures you are more likely to recognize. The squid-like larval origin of starfish, in particular, is a fascinating thing.

One final note — Dr. Kirby mentions that plankton are responsible for the characteristic smell of the sea. That is not surprising to me. When I was a grad student in plant pathology at Cornell, I was startled one day to discover that dirt doesn’t smell like dirt. Dirt smells like the bacteria that are living in dirt. In one lab we were allowed to sniff (I believe “waft” is the preferred term) a pure culture of soil bacteria. It was a clear agar dish with opaque colonies of bacteria. But it smelled just like fresh topsoil or a cave — dirty, earthy, wonderful.

Discovered thanks to the fine staff of Deep Sea News.

Still Life with Vienna Sausages with Tails: A Choleric Work in the Style of Pollack. Photo courtesy CDC Public Health Image Library, Image #1034.

Vibrio cholerae is a bacterium of surprising adaptability, tenacity, and Olympic-class swimming ability. Cholera bacteria can swim in both freshwater and saltwater (a feat most fish cannot manage), and somehow also manage to do the backstroke through stomach acid without kicking the bucket. The historic killer has just popped up again in Papua New Guinea for the first time in 50 years, killing 40. Officials are worried that it may once again become endemic there, taking up residence in the locals’ water supply.

And this is despite our knowing exactly how to prevent the disease for well over 150 years, ever since British physician John Snow famously helped halt a London cholera epidemic by persuading the authorities to abscond with the handle to the Broad Street Pump, preventing people from drawing its lethal waters. There’s only so much science can do. Money and competency are also required.

King Cholera

Cholera is a disease you have probably at least read about if you did any of the required 19th-century high-school lit reading. That’s because it was a newly famous and successful killer that century, decimating millions globally and hundreds of thousands in the United States, as the bacteria spread along coasts and up and down rivers. It was a swift death, too, and until mid-century, no one knew the cause.

A few years ago I visited some old graves out on the lonely prairie of Nebraska near the inland-sea-sized Lake McConaughy at Ash Hollow State Park. Buried there was Rachel Warren Pattison, a young woman who traveled the Oregon Trail in perfect health one day and was dead of cholera the next. Her party, including her 23-year-old husband of two months, Nathan, had only a few hours to carve a marker for her before the wagons moved on, and miraculously, in an uneven but serviceable hand on a rough stone, they did. I stared at that marker a long time. Sometimes I think modern, first-world citizens greatly take for granted the fact that most of us will not randomly keel over tomorrow from some fatal and unpreventable disease. Before the 20th century, people everywhere lived with that fear (and reality). Imagine how your life would be different if you lived with that reality now.

Cholera, Bringer of Death

In any case, Rachel was but one of the 6,000-12,000 killed along the Oregon, California, and Mormon Trails between 1849, the year of the gold rush, when cholera was spread along the trail by prospectors and settlers, and 1855, when the pandemic ended. And that epidemic was just one tiny sliver of the half dozen major pandemics that covered the world that century, a product of globalization and colonialism. Before 1816, cholera seems to have been a local disease restricted to India. But with people increasingly traveling between east and west, it swiftly leached into waterways around the globe. In the UK, where the disease claimed tens of thousands of lives in the first wave in 1831-32 alone, it began to be called “King Cholera”.

What made and still makes cholera such a frightening disease was the speed with which it could (and can) kill. Death can come as quickly as 3 hours after the onset of symptoms, but more commonly within 24 hours. Its most famous symptom — thin diarrhea descriptively called “rice-water” stool — accurately indicates the cause of death. You die from lack of fluids. That’s it.

Cholera bacteria use their tails (flagella) to propel themselves into the walls of your intestinal cells, where they secrete a toxin that causes cells to expel chloride ions. This, in turn, creates ionic pressure that keeps sodium from entering cells. That causes osmotic pressure to build on the outside of the cell, drawing massive amounts of fluid into the intestine. Building reliable sewage and water treatment plants prevents deaths, as does simply keeping cholera victims hydrated with a simple electrolyte solution. That we can’t manage even that that in many parts of the world is as discouraging as it is laughable.

Ancestors in the Deep

But here’s the really interesting thing about cholera, at least from my perspective: scientists are discovering that cholera seems to be an inherently aquatic and previously deep-sea bacterium that evolved to peacefully colonize copepod shells and mollusc interiors, and only accidentally turned out to be good at violently colonizing human small intestines. Wow!

In 1999, the submersibles Alvin and Nautile visited hydrothermal vents at the East Pacific Rise and sampled sulfide chimneys there. Vibrio species were identified there with “significant similarity” to V. cholerae, according to past NSF-director Rita Colwell, who has studied cholera since the beginning of her career.

Modern V. cholerae colonize the outside of copepod shells (Remember copepods from here and here?) and the insides of shellfish and must compete for space there in the life-sustaining biofilm. It turns out that those that are best at attaching to copoped shells also happen to be most pathogenic in humans. And a mucinase (enzyme that breaks down intestinal mucus) that helps them attach your intestines is greatly aided in its work by the addition of an extract made from mussels. That is, eating shellfish contaminated with cholera make make matters way worse than simply drinking the bacteria.

Deadly cheetohs -- the rod-shaped bacteria V. cholerae. Courtesy Dartmouth Electron Microscope Facility.

Living with Vibrio

Cholera is probably not an eradicable disease, according to Colwell, since we seem to be only accidental victims, while copepods and cholera are the real story. Since they’re ubiquitious and may be providing some important ecological function, we must instead rely on ingenuity and engineering to keep us safe. Basic sewage and clean water systems for all people of Earth does not seem like an unreasonable demand.

Two interesting human genetic notes regarding cholera: you may already know that Sickle Cell Anemia is widely considered to be a by-product of the genetic advantage that having one copy of the harmful gene provides during malaria infection. With one copy, you get malaria protection; with two copies, you get sickle cell anemia. Some have speculated that cystic fibrosis is a two-copy gene problem produced by a single copy that confers resistance to cholera. As well, blood types seem to confer various protections (though not immunities) from cholera: AB blood is most resistant, followed by A, then B, then O.

Vibrio is in the gamma-proteobacteria, a group you can find on the tree of life here (click on Proteobacteria to drill it down a bit). Gamma-proteobacteria contain many human pathogens, including Yersinia pestis (the cause of plague), Salmonella, Escherichia coli, and Pseudomonas aeruginosa, a cause of lung infections in (ironically) cystic fibrosis patients and other ill people.

But don’t get the idea that gamma-proteobacteria are mostly human pathogens. My gut(!) tells me they’re probably the exception, rather than the rule. We just happen to know more about them because there’s money to study human pathogens. The rest of the (probably amazingly interesting) group languish in obscurity. Don’t believe me? Look at all the families here.

"Treats? Where!?" The social bacterium Treponema pallidum. (Subtle, very subtle)

This one goes out to those of you who think all bacteria are either boring rods or balls. (BTW, is it just me, or does this video have a strange first-moon-landing-recording-esque quality?)

Eat your heart out, physicists, engineers and animal behaviorists — you can’t say you’re not impressed here. Wave forms? Relaxation pattern? Forward and reverse? Not bad for a tidy .5 x 5-250 micrometer package. In case it’s still not clear, spirochetes (spy’-row-keets) are helical bacteria, and one of their members is the infamous Borrelia burgdorferi, the party behind Lyme Disease, the species in the video above. So is Treponema pallidum, the maker of Syphillis (TM). That’s right. Don’t mess with the ‘chetes.

Well. . . maybe not. In spite of what you might think from our highly skewed sample size of 2, most spirochetes are not nasty human parasites. They are free-living, oxygen-avoiding, bread-winning, welfare-eschewing bacteria. Incidentally, Spirochetes represent a happy accident of taxonomy. In the old days, microbes often got classified by shape. So all the spirochetes got lumped together. Turns out that actually reflects true kinship in this case. Lucky us! At least one taxon we don’t have to split and relearn!

For a look at all the groups of Eubacteria spirochetes are related to, click here. Once there, you can click on “Spirochetes” for a look at some of the specific genera in the group.

Thank you, YouTube, for making such wonders freely available to us all . . .

Apparently, in addition to all things jelly, I’m fascinated by all things blobby. You’ll note the restraint I used in not posting anything about that blob they found floating off the coast of Alaska last summer. It seemed obvious right from the start that that was simply your run-of-the mill algal bloom. These blobs, on the other hand, would quite mystify me without  the help of a reassuring National Geographic narrator.

I’m pretty sure this is the same stuff that builds up in the water you leave the dishes in the sink too long. Is it just me or did you also half-expect to see an eyeball or two floating around in one of those things?

It seems like this may be some sort of biofilm, which is a very sexy subject in the world of biology right now. Biofilms are essentially thin coats of bacteria and bacterial slime (technically known as extracellular polymeric substance, or EPS) on teeth, stream cobbles, catheters, lawyers, etc. (just kidding lawyers! Don’t sue!)  These things are apparently everywhere — even on the thin skin of water at the surface of the ocean — and this way of life represents an up-till-now severely underappreciated bacterial lifestyle. 99 percent of bacteria may live in biofilms.

And yet  these don’t seem like classic biofilms as they aren’t tightly packed or adhered to a surface. They seem to be somewhere in the no-man’s-land between a biofilm and marine snow, the slow rain of decaying microbial matter that eventually coats the ocean floor. Both marine snow and mucilages incorporate much more than just bacteria — like crustaceans, plankton and viruses. For whatever reason the marine snow in the northeastern Mediterranean is piling up faster than the life in the water column or on the sea floor can take it out. Which seems odd, because in the deep sea, the locals will quickly consume anything that isn’t ballistic-grade plastic, and I’m pretty sure they have their R&D departments working on that too.

Whatever they are, they are unusual, and probably prospering by climate change. I love weird manifestations of life, but there is good-weird and there is bad-weird. The kind of weird that smothers fish and spreads E. coli is definitely bad-weird.

For the PLoS paper that inspired this video, click here.