Evolution as a Tool: Has Anyone Tried It?

[Jikx]

has anyone tried using evolution as a tool?

For example, I can envision an experiment where a colony of E.Coli is grown in ever increasing levels of radiation, after after say a year and a couple of million replications later, I would end up with E.Coli that would be very resistant to radiation.

I can see where this could be used, such as replacing the radiation, with say some sort of toxic chemical like DDT, and just keep increasing the dosage, and maybe some resistance will form or even better, a new protein that could degrade it. Something similar done before?

 

[iansmith]

A prof I had was a food microbiologist and his these was to increase the alcohol tolerance of yeast. By sub-culturing resistant yeast colonies on agar with increasing concentration of alcohol, he was able to isolate a yeast strain that could tolerate 26% alcohol in the media.

According to the same prof, radiation resistance evolution was evaluated by passing bacteria at the same level of radiation.

The opposite can also be done to cause a bacteria to be an auxotroph.

You are basically describing is some of the old method use to isolate mutants and I am sure there is plenty example in the litterature.

 

[Jikx]

agh.. no patent then.. damnit.

 

[iansmith]

yeah some smart people where born before you, and I know, it sucks!

 

[Chrono]

yeah some smart people where born before you, and I know, it sucks!

I know, it does suck. Look at the bright side; at least they can teach you what they know.

 

[Moonbear]

jikx, note that in order to select a strain resistant to radiation or a toxin, or whatever insult you throw at it, the original organism already needs to have that trait in order for some of the colony to survive. From the original post, it isn't clear if you already understood that or not.

 

[Jikx]

So such a trait cannot evolve? If you start at a really low concentrations of a highly toxic element, that which has never been naturally produced, its not possible for the bacteria to develop resistance?

Its interesting because humans have made many chemicals that are literally "man made" - no biological analogue exists. Thus, its not ikely that any organism on Earth would be able to degrade it. Would it be possible to, so to speak, give nature a helping hand? Start at tiny amounts, and scale up as defences (eventually? even possible?) kick in.

 

[iansmith]

So such a trait cannot evolve? If you start at a really low concentrations of a highly toxic element, that which has never been naturally produced, its not possible for the bacteria to develop resistance?

A mutation has to be there when the toxic element is added. The mutation will be selected. However, there no evidence that "beneficial' mutation can arise after the bacteria has been subject to selection. This process was called "adaptive" mutation. Basicaly, for mutation that are already there before selection, colonies will appear within the expected growth time. For mutation that are adaptive, colonies will appear several days after the expected growth time.

You might want to read these paper:

Hersh, M.N., Ponder, R.G., Hastings, P.J., Rosenberg, S.M. 2004. Adaptive mutation and amplification in Escherichia coli: two pathways of genome adaptation under stress. Res. Microbiol. 15: 352-359.

Foster, P.L. 2000. Adaptive mutation: implications for evolution. Bioessays. 22: 1067-1074.