Top Ten Bacteria

By Ed Yong | December 5, 2008 11:39 am

I don’t usually do memes, but I couldn’t resist this one and it gives me a chance to remind myself (and you) of some really amazing recent research. So without further ado…

Top Ten Bacteria – the Not Exactly Rocket Science edition

Carsonella.jpg10. Carsonella ruddii

Possessor of the smallest bacterial genome known, C.ruddii has lost the majority of its genes and in doing so, its independence. Its genome is too small to allow it to survive on its own and it requires the room and board provided by its insect hosts whose genomes now host C.ruddii’s genetic donations.

9. Pseudomonas syringae

Dreaming of a white Christmas? This species can help. It has a protein on its surface that mimics that structure of an ice crystal, acting as template for other water molecules to latch onto. The upshot is that this bacterium is a living ice-maker, seeding the growth of snowflakes. And they are found in snow from France to the US to Antarctica.

See the top eight below the fold

epulo1.jpg8. Epulopiscium spp

The big boy of the kingdom – about as large as this full stop. By having thousands of copies of its own genome (about 40 times more DNA than a human cell contains), Epulopiscium can shrug off the constraints that limit the size of most bacteria, and grow to enormous proportions. This species gets bonus points for its supremely fussy choice of host – the intestines of the bulbnose unicornfish. Want to study Epulopiscium? Better work on your spear-fishing skills.

715px-salmonellaniaid.jpg7. Salmonella typhimurium

A food-poisoning bug, and a seemingly innocuous choice. But think again. Send it into space, and Salmonella becomes a super-bug – more virulent and more resistant than its Earth-bound cousins.

6. Escherichia coli

The classic. Surely no list would be complete without it. See Carl Zimmer’s new book Microcosm for a myriad of reasons for why E.coli is still one of the single most important species in modern science.

yersinia_pestis_fluorescent.jpg5. Yersinia pestis 

This list could very well have just focused on disease-causing species, but I wanted to be more selective. So goodbye, Vibiro cholerae. Out you go, Bacillus anthracis. Fare thee well, Mycobacterium tuberculosis. Make way for the big daddy of them all – the bacterium responsible for the bubonic plague. If you absolutely, positively have to kill every last motherf£%£$r on the continent, accept no substitutes. And it’s even managed to pilfer a bit of drug resistance from the No.7 pick!

4. Myxococcus xanthus

The bacterial equivalent of a wolf pack – these social hunters move in tight huddles, secreting digestive enzymes that break down cells in their path. But it’s when they run out of food that they show their most amazing cooperative behaviour. They clump together to form “fruiting bodies” and some of them even top themselves for the good of their peers, releasing their own contents to feed their neighbours.

3. Deinococcus radiodurans

Hardier than a cockroach – the “terrifying berry that withstands radiation” can shrug off doses of radiation 1,500 times greater than what would kill a human. DNA repair is the key to its awesome powers – as with other species, radiation tears its genome into tiny fragments, but D.radiodurans can happily reassemble its shredded DNA.

Daudaxviator.jpg2. Desulforudis audaxviator

One special population of this “bold traveller” has turned into a bit of an ecological hermit. In the depths of one South African gold mine, D.audaxviator lives in complete isolation from not only the Sun’s energy, but all other species. It’s the only thing alive in this remarkable ecosystem of one.

1. Wolbalchia spp

A poster-child for selfishness, and arguably the most successful parasite on the planet. Who cares about the species that infect pathetic humans? If you want a true path to world domination, you’re better off targeting the world’s most diverse group of animals – the insects. Wolbachia has a number of tricks up its membrane for making sure that it’s passed on from parent to offspring, from rendering a host asexual to killing off an entire gender. In one extreme case, it’s even inserted its entire genome into that of a fly. See also LOLbalchia .

MORE ABOUT: Bacteria

Comments (9)

  1. Dr. Kate

    How does having lots of DNA help Epulopiscium grow big? I thought the primary limiting factor in bacterial size was surface area/volume ratio–i.e., getting stuff into and out of the cell. Bacteria don’t have organelles, so have to rely on diffusion. Or have I been misinformed?
    Also, I’m sad that Geobacter spp. didn’t make your list. They turn mud into electricity! How cool is that!!

  2. Great list! Epulopiscium spp is freaking awesome. Anything that large containing that many copies of its genome must be cool…right? I am hoping to get my list up on Monday and I suspect there will be a tiny bit of overlap. It is kind of hard to leave off Myxo and Deinococcus.

  3. No Kate, you’re right. I didn’t have space to go into the full Epulopiscium story, but you can read more if you follow the link. But here’s the relevant bit:
    “The bacterium’s extra genetic material is dotted around its edges, near the cell membrane. This means that new proteins can be created and directly fed into the membrane without any transport problems, in the same way that a retailer can minimise shipping delays by having multiple warehouses dotted around a region rather than a single central depot. This division of labour allows a single Epulopiscium cell can act as a colony with different parts responding independently to local conditions.”

  4. Dangit, I forgot about #9 as well as O.oeni on my own list. Some advocate for the usefulness of microbes I’m turning to be…
    Geobacter and Geothrix species would have made my list as well, if I hadn’t already run out of room.

  5. Oooo nice list!! Who knew Desulforudis audaxviator is 100% a hermit, I really didn’t think that was possible…thanks for some newfound knowledge!

  6. Excellent list!
    Microbiology rules!

  7. Glad to see D. rad making the list. Besides the radiation tolerance, it’s also a great model organism for studying persistence due to the fact that colonies in a persistent state are visibly different from the wild-type.

  8. Tracis Stark

    Is this based on looks, because I think that Wolbalchia spp would still be #1. This is an awesome top ten list, you should post this to my buddy’s site and you can link back to your site. You can also let other people vote on the rankings if you want.

  9. Carsonella as the bacterium with the smallest bacterial genome known…?
    Well,cladistics insists that we classify organisms only by the order of evolutionary branching and not by evolutionary innovations etc, so mitochondria are members of the clade Bacteria, and they beat Carsonella to the title of smallest bacterial genome by a considerable margin. Your mitochondrial genome is only 16.6kbp, a tenth of Carsonella’s 160kbp genome
    But if one wanted to enter the outer fringes of philosophical phylogenetics, consider the hydrogenosome of Trichomonas, which is thought to be derived from a mitochondrial/bacterial ancestor, but which entirely lacks its own genome. You can’t get smaller than zero base pairs! A phylogenetic example of Theseus’s paradox!


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