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Comment by msds | Hacker News Reader

This is kinda my space right now - remarkably hard-to-kill bacteria. Some fun stuff:

1) Ralstonia pickettii doesn't really need much to eat, and thus thrives in ultra-pure water systems. Like, you know, the ones used to make medical devices.

2) Stuff in the Burkholderia cepacia complex is naturally resistant to lots of antibiotics, but also tolerates chlorhexidine gluconate and various quaternary ammonium disinfectants. Well, ok, more than tolerates - they'll happily colonize the disinfectant solutions, and then infect whatever you're trying to "disinfect".

3) Deinococcus radiodurans seems almost engineered to survive interstellar travel, but that's probably just a coincidence. Anything that can survive 15,000 Gray is scary.

4) Bacillus altitudinis is pretty weird too - like the name says, it's been found up to 40ish-km, which is an odd place for things to grow.

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Wow that's very interesting. What do they do with 1) and 2)? Just accept it or kill it another way?

Why is 3) so resistant against radiation? Does it repair DNA damage faster than it occurs?

Do you mind me asking if you're working in industry or are in academia/research? :)

Kill it some other way, and frequently test things that should be 'sterile'.

I don't actually study (3) particularly, nor am I a biologist. As far as I understand, the "how" question is pretty well studied, and is because it's pretty aggressive with DNA repair, and has lots of various tricks to facilitate that and minimize damage from occurring in the first place. The question of "why" is (in my mind) more interesting, and less understood - it may be due to evolving to deal with prolonged dehydration, which is a much more useful ability for life on earth. IDK.

R&D at a startup.

Thanks for the reply – I actually thought there was some stuff no bacteria could live in and that probably exists, but then you also get problems with the things you are trying to desinfect.

Excuse my ignorance. Are there any bacteria that have some type of resistance to bleach? This scares me.

Yes, and No.

No in the sense that phospholipids and proteins and hydrocarbons in general are delicious to bleach. Exactly like asking if there are bacteria that can survive being incinerated in a fire, at a chemical level the molecules in their cell walls get broken up. There is no simple hack a unicellular organism can apply to survive strong enough bleach or fire, at a very low chemical level its being destroyed. Would silicon based life tolerate bleach? I'd have to think about that a bit.

Yes in the sense that if you play games with very low concentrations you will slowly preferentially breed stronger cells, much as you could breed fire resistant wood, but all wood vaporizes in a strong incinerator. Obviously Homeopathy is not a thing scientifically, a small amount of bleach dumped in a pond won't kill everything in the pond but it will kill the weakest whatever in the lake, leading to increased breeding of stuff resistant to extremely low bleach concentrations. However even in theory I don't think anything could live in a bottle of normal strength bleach.

There are also categorical issues, a very thick layer of algae when splashed with bleach will have the outer layer die and eventually melt off, but the layer underneath will simply regrow. Does that mean algae is resistant in the overall system sense even though it dies really easily? People are usually only interested in systemic success, so sure, its very easy for bacteria to survive bleach based cleaning. A nice thin layer of bulk grease or oil that lasts long enough to protect at least some bacteria underneath that isn't completely removed during the cleaning, there you go, bacteria that survived bleach cleaning, although no bacteria individually can survive full strength bleach, a sufficiently thick layer of grease protecting some bacteria can survive a sufficiently short enough bleach cleaning process.

Intriguing & fascinated. The very idea of bacteria producing stronger cells in response to chemical agents in relatively short periods of time is an idea I can ponder for hours. Thank you.

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