Field of Science

Xtreme bacteria! - SGM series

This is the third post in the SGM series and this one is about Extremophiles. There were lots of talks in this topic, so instead of a serious research-analysis post, this will just be a quick run-down of some of the more interesting bacteria that were covered:

Award for : Survival under extreme acidity
This award is presented to the Natranaerobiales species that live in sun-heated salt lakes in the Middle East and Africa. These can grow at conditions of Ph 3.7 and also manage to survive at 66 degrees Celsius, by using specially modified proteins to carry out vital cellular tasks.

Award for: Coldest temperature - thermophiles
Theremophiles are bacteria that are found only in very hot temperatures, so researchers were rather surprised when an experimental heating up of arctic ice to 50 degrees stimulated a range of dormant thermophiles to spring to life. What the bacteria were doing there, what kind of global warming event they were waiting for, and why researchers were heating up arctic ice to 50 degrees anyway remains to be discovered...

Award for: Resistance to radiation
This award collected on behalf of all radiation resistant bacteria by Deinococcus radiodurans. Recent work in these bacteria revealed that there is a mechanistic link between resistance to radiation, protein protection and (rather weirdly) manganese accumulation. Apparently surplus manganese in cells can help against reactive oxygen species.

Award for: Survival at greatest pressure range
The deep-sea bacteria Photobacterium profundum is not only able to survive at 15 degrees C, but also lives at a pressure of 28MPa (atmospheric pressure being 0.1MPa). Any eukaryotes living at that pressure tend to unfortunately explode when brought to the surface, but these bacteria are able to survive fine at normal pressures. (Scientific aside - their cell surface lipopolysaccharide composition is thought to help with the cold survival. Mutants that are cold sensitive have a lower concentration of smooth LPS than the cold-adapted parents).

Award for: Best attempt at mimicking a B-list Sci-Fi alien
I'm not sure whether this should be given to the bacteria, or the people who wrote the abstract, but to give you a clue the talk is titled "Dark life in the fracture labyrinth of deep hard rock". Bacteria have been found in rock fissures living in complete darkness with hardly any organic minerals, and using hydrogen as an energy source. Or, in the words of the abstract, "An extreme ecosystem that survives in total darkness feeding by hydrogen from the interior of our planet". If these things weren't tiny blobs that would be a movie already.

Honorable mention: Extreme fungi
This was a microbiology conference, not a bacteriology one, which means that it also covered fungi, algae and protists. Fungi have been found that live at high salt concentrations, both high and low temperatures, acidic and basic conditions, high hydrostatic pressure, high ionizing radiation and in extremely toxic environments.

Honorable mention: The virus's of Haloquadratum
These little guys are getting an honorable mention just because they seem to be the only virus's mentioned in the entire talk. They infect the bacteria Haloquadratum and are thought to have played a role in the development of the bacterium's resistance to high salt levels.

That's all the awards for now! Just four more of the SGM series to go, I'm enjoying writing them, even if the "one post every two days" hasn't quite happened.

7 comments:

Anonymous said...

It's "viruses", not "virus's".

Anonymous said...

How about an honorable mention for the oldest bacteria discovered?

http://boingboing.net/2009/06/17/salty-microbe-may-be.html

Mike said...

Dude! Make more :)

-Mike

Anonymous said...

Is "15 degrees C" a typo? It a bit cool but hardly extreme.

Lab Rat said...

Thanks for all the comments! In response to the last anonymous, 15 degrees is not a typo, and it's fairly exciting for a single cell. And that award was for the pressure anyway, the temperature was just a bit of an aside.

Patrik said...

Hm...

- Survival under extreme acidity: the Acid Mine Drainage communities studied by Jill Banfield & Co (see http://seismo.berkeley.edu/~jill/amd/AMDhome.html) live at pH < 1! I like to call it "arsenic laden battery acid"...

- 15 Celsius is bupkis for most environmental organisms - hardly worth mentioning. Besides, Photobacterium profundum actually grows at least at 70Mpa at 10 Celsius, and at 4 Celsius under atmospheric pressure (see http://www.ncbi.nlm.nih.gov/pubmed/9676237). That's *growth*, mind you... it can probably *survive* in a much wider range.

Lab Rat said...

@patrik: Thanks for the information! This list was working specifically off bacterial species mentioned during the SGM Autumn conference, so I know I missed some of the more awesome ones. I'll definitely check out the link for the <pH1 bacteria, that sounds like a hell of a challenge.