Medium-term storage of bacteria

[Mega]

Hi everyone,


I have got bacteria that carry a plasmid that encodes resistance ageainst tetracyclin.

They are on Tetracyclin-Agar plates. Can I just store them in the fridge for a few months?


I mean, I once stored Ampicillin resistant E.Coli on Amp plates for (don't remember the exact number 3-5 months). Then re-plated it on fresh LB Amp agar, and they grew without problems.

However tetracyclin has to be actively transported out of cells. Now that they were metabolically inactive, the tetracyclin has entered the cell by osmosis.
When they "wake up" again, they probably won't be able to pump it out again, right?

Other theory: It works bacteriostatic, that means, only when cells divide they get killed. So the bacteria resume metabolic activity, and pump out the antibiotic. Then they divide without any problems...


Anyone experience with this?

[Eric Ma]

In the fridge, the bacteria aren't metabolically inactive. They're just less metabolically active. Diffusion also proceeds at a slower rate at lower temperatures too. A few months for a plate with visible colonies is probably stretching it, but my naive suggestion (i.e. I've never tried this, but it looks like it'd work) would be you could always streak them out onto a fresh plate and store the fresh plate at 4ºC for a few months, without sealing the plates with parafilm, and then stick them into 37ºC the night before you need to grow overnight cultures.

Now, the only thing is that you'd have to look out for contaminant fungi growing on those plates, that's all...  

Cheers,
Eric
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[Mega]

Ok thanks... 

Will post if the agrobacteria (those are tetracycline resistant due to pSoup)  are still "alive" ;) 

[Dakota Hamill]

Now, the only thing is that you'd have to look out for contaminant fungi growing on those plates, that's all... 

I left some PDA Plates sealed up in a bag in a fridge for three months, came back and found only one plate was covered by an entire fungal colony.  I was actually pretty pumped up, because I'm interested in fungi, and it was really neat to think how well it grew at 4C!

I wish I kept it some spores of it come to think of it...

Nature is crazy