A Trip Down the Microbial Rabbit Hole

by Jennifer Frazer on October 31, 2009

“Where the telescope ends, the microscope begins. Which of the two has the grander view?” – Victor Hugo

I think you all know how I would answer that question.

Pollen from sunflower (Helianthus annuus), morning glory Ipomoea purpurea, hollyhock (Sildalcea malviflora), lily (Lilium auratum), primrose (Oenothera fruticosa) and castor bean (Ricinus communis). 500X magnification; the bean-shaped pollen grain at lower left if 50 micrometers (μm) long. Believe it or not, these microbes are actually an entire male plant -- the gametophyte.

Pollen from sunflower, morning glory, hollyhock, lily, primrose, and castor bean plants. 500X magnification; the bean-shaped pollen grain at lower left if 50 micrometers (μm) long. Believe it or not, these microbes are actually an entire plant -- the male gametophyte.

This blog is all about the variety of life, but part of that variety are the enormously different scales at which life can exist. You may know blue whales are the largest animals (ever, actually. Ever.), but they are not the largest organisms. Trees (aspen are notorious for this — one called Pando in Utah in paticular), fungi (remember the humongous fungus?), and perhaps a mediterranean sea grass called Posidonia oceanica can grow to many square kilometers courtesy their ability to grow asexually and keep at it for thousands of years. Life exists in a contiuum from these titans all the way down to the tiniest bacteria and archaea, the smallest of which are in the 200-400 nanometer range, round about the size of the measles virus.

Now the University of Utah has created an animation with a simple slider bar that takes you from coffee bean to carbon atom and back again. Check it out! Notice, for example, the amoeba (yay! Our site mascot!) approaches the size of the grain of salt and is visible to the naked eye when the animation is zoomed all the way out. If I were a bacterium or yeast cell, I’d cower too!

Notice also that mitochondria, the descendants of bacteria engulfed by ancestral eukaryotic cells (all cells except bacteria and archaea) billions of years ago, are actually slightly bigger than, but still more or less the same size as, E. coli. Notice that measles virus next to it — which gives the scale for the tiniest known cells mentioned above. Zoom in and out to compare this to the size of the amoeba or paramecium, and think about the fact they are both what we call “single-celled organisms”. Yet if the biggest amoeba or smallest bacterium had eyes, they probably wouldn’t be able to see each other. They are an order of magnitude (1000 times) different in size — and the difference is 10 times the difference between blue whales and us!

Don’t miss the question at the bottom either, which shows what amazing packers you boys are. A sample:

How can an X chromosome be nearly as big as the head of the sperm cell?

No, this isn’t a mistake. First, there’s less DNA (half as much, actually –jf) in a sperm cell than there is in a non-reproductive cell such as a skin cell. Second, the DNA in a sperm cell is super-condensed and compacted into a highly dense form. Third, the head of a sperm cell is almost all nucleus. Most of the cytoplasm has been squeezed out in order to make the sperm an efficient torpedo-like swimming machine.

Why do I get the feeling that last sentence will inordinately please the gentlemen out there? : )

{ 6 comments… read them below or add one }

Oroboros October 31, 2009 at 6:44 pm

For kicks I tracked down the dimensions of Herminiimonas glaciei, an ancient ultramicrobacteria that was revived from a sleep of 120,000 years last summer. Wikipedia says it is 0.5–0.9 by 0.3–0.4 µm which I think puts it between the lysosome and measles. While digging for that information I also ran across this sobering thought:

“H glaciei isn’t a pathogen and is not harmful to humans”, Dr Loveland-Curtze added, “but it can pass through a 0.2 micron filter, which is the filter pore size commonly used in sterilization of fluids in laboratories and hospitals. If there are other ultra-small bacteria that are pathogens, then they could be present in solutions presumed to be sterile. In a clear solution very tiny cells might grow but not create the density sufficient to make the solution cloudy”.

On the other end of the scale, the BBC recently recorded the “greatest animal battle on the planet”, the female humpback whale heat run. Maybe there’s something there for females to be pleased about?

Daniel Poth November 2, 2009 at 9:29 am


“Mr. Jack, fire 1 torpedo. Fire 2 torpedo…. Fire 1,395,023 torpedo.”

sdutchen November 2, 2009 at 6:48 pm

Way cool. I’ve been thinking more about scale lately between proteins and stars — the epigraph is perfect — and the image feels more like art than photography.

As a budding science blogger (which, I’m learning, is different from my other blogging), one of these days I’d like to ask you about how you put together these posts and how long it takes.

Jennifer Frazer November 2, 2009 at 8:38 pm

I’m not too worried about ultramicrobacteria in hospitals. If it was a problem, we would have figured out by now that something was getting through our sterilization systems. In fact, we did figure that out about 100 years ago. Something was making people sick that was small enough to pass through filters that could catch bacteria. We couldn’t see them yet and had no idea what they were, but we knew they were there. We called them viruses. Most hospitals autoclave (put stuff into a heat, steam, and pressure death chamber) all their stuff anyway, and that sterilization system isn’t dependent on filters. But you never know! They didn’t figure out 95% of ulcers were caused by Helicobacter pylori bacteria until 15 years ago . . .

A much more frightening thought to me personally is that we KNOW our existing standard sterilization systems do not deactivate prions. So if they operate on someone with Creutzfeldt-Jakob or Mad Cow Disease without knowing it and use the same ostensibly sterilized equipment on you, you can get a fatal brain wasting disease!

Thanks, and ask away sdutchen! Email me off site, if you like. My address is on my Portfolio page.

Oroboros November 3, 2009 at 4:02 pm

I was treated for a presumed H. pylori infection before it reached ulcer stage, and it seems to have helped (antibiotics + proton-pump inhibitor). My physician mentioned that it is more prevalent in the west for some reason. Since I developed symptoms within a few years of moving here I wondered if there might be a dietary correlation. I don’t think I’ve ever eaten chorizo back east. Maybe there is something different in the sausage casings that allows it to survive and it has another host? I found this reference to something similar in pigs that also notes that dogs can carry it too. But this other site puts more of the blame on cats.

Your comment about viruses reminds me of something from Lives of a Cell which is one of my favorite books and perhaps worth quoting on the subject of the scales of life. I certainly didn’t appreciate the fact that bacteria were susceptible to viral infections before reading this:

In real life, however, even in our worst circumstances we have always been a relatively minor interest of the vast microbial world. Pathogenicity is not the rule. Indeed, it occurs so infrequently and involves such a relatively small number of species, considering the huge population of bacteria on the earth, that it has a freakish aspect. Disease usually results from inconclusive negotiations for symbiosis, an overstepping of the line by one side or the other, a biological misinterpretation of borders.

Some bacteria are only harmful to us when they make exotoxins, and they only do this when they are, in a sense, diseased themselves. The toxins of diphtheria bacilli and streptococci are produced when the organisms have been infected by bacteriophage; it is the virus that provides the code for toxin. Uninfected bacteria are uninformed. When we catch diphtheria it is a virus infection, but not of us. Our involvement is not that of an adversary in a straightforward game, but more like blundering into someone else’s accident.

He also says some interesting things about how our bodies respond to gram-negative bacteria, and I see that H. pylori is one. My recollection of Thomas on it now is that gram-negative bacteria aren’t inherently harmful (as far as they could tell at the time), but they provoke a bad response from the immune system that causes more harm than the invader itself. The book is old enough that I’m sure some parts of it aren’t accurate any longer. He did get me fascinated by mitochondria though. I just started reading Power, Sex, Suicide: Mitochondria and the Meaning of Life.

I definitely agree that prions are the one of the scariest things we know about.

P.S. Thank you for adding the list of allowed HTML tags below the comment submission form :)

Captain Skellett November 5, 2009 at 1:04 am

That picture is absolutely stunning.

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