transporting E coli on filter paper - (Mar/29/2012 )
I was moving to a new lab and brought my bacteria strains over by air drying cultures of them on filter paper. I wrapped them up in weighing paper and aluminium foil on the outside. I carried it in my hand luggage (ie went through all the X-ray). It was not exposed to extreme heat. For most of the trip, it was ~25C and when I got to my destination, it was mostly below 15C. However, when I finally got to the lab after ~12 days, I could not revive them. What I did was I added a drop of LB to the filter paper, incubated at 37C for 1 h and smeared it on selective plates. Then, I dropped the paper into selective liquid media. There was no colony or cell growth at all.
I know that inoculating bacteria on filter paper for mailing is a common practice. There is this thread from this forum (http://www.protocol-online.org/biology-forums/posts/7295.html). Also, CGSC sends out KEIO collection strains on paper too. So what did I do wrongly? Should I have sent them moist or recover in non-selective medium first? I'm trying to figure this out so I could get people from my lab to send some over to me. Thanks!
Not sure why you used selective medium.. thats not a good idea. You need general medium first because the cells need to "revive" , get their metabolism back in oirder and putting them on selective medium is not a good idea to start with.
Also there is no colony growth, but how long did you wait?
Why didnt you use freezedried samples or agarslants?
One thing you need to keep in mind: never bet on one horse and before you start betting, make sure you know on what you are betting!
What I mean is: you should have tried it before , to see if it works! ANd you sould have maybe used 2 different ways to make sure there is at least 1 working... (there are things that can go wrong...==> let the people in your lab make new samples and let them store it a few days, or why not, let them mail it to themself at home, bring it back to the lab and check if it works... it should be possible!)
Its very hard to tell what went wrong really.
I actually moisten the paper with plain LB and incubated for 1 h before I placed them on selective plate/medium. I guess that was not enough. In retrospect, I probably should have grown them up in plain LB and streak the overnight culture on selective plates. Btw, the plates were incubated for 2 days.
I didn't use agar slant as I wanted the most convenient and inconspicuous way to bring it with me onto the plane. I was afraid agar slant would be a bit suspicious on the X-ray. I read a paper that recovery from freeze dried cells is lower than air dried ones.
I would have tried but it was a hasty departure and I didn't have the time to test it out. Also, I was searching the web and it seems like a routine procedure. I have seen a colleague recover cells from a disc sent by CGSC and she got a lawn of colonies.
donny on Thu Mar 29 19:12:53 2012 said:
I actually moisten the paper with plain LB and incubated for 1 h before I placed them on selective plate/medium. I guess that was not enough. In retrospect, I probably should have grown them up in plain LB and streak the overnight culture on selective plates. Btw, the plates were incubated for 2 days.
I didn't use agar slant as I wanted the most convenient and inconspicuous way to bring it with me onto the plane. I was afraid agar slant would be a bit suspicious on the X-ray. I read a paper that recovery from freeze dried cells is lower than air dried ones.
I would have tried but it was a hasty departure and I didn't have the time to test it out. Also, I was searching the web and it seems like a routine procedure. I have seen a colleague recover cells from a disc sent by CGSC and she got a lawn of colonies.
Eum, "inconspicuous" way.. there are options to send/traval with bacterial products..
But I can see where it comes from, you had no time and needed the fastest possible way.
Its possible that the only reason why it failed is exactly the fact you didnt give the bacteria time enough to recuperate.. (1hour was maybe too short).
I hope you manage to grow them up next time, but its hard to tell what went wrong here.
All I can say is: check the advise about how to make those filter paper "things" and how to recuperate them. Just check the protocols and stick to that and normally it should go well then.
I'm guessing that the problem was that you let the paper dry out. I think the foil is intended to keep the paper inside sterile and moist.
phage434 on Thu Mar 29 19:51:27 2012 said:
I'm guessing that the problem was that you let the paper dry out. I think the foil is intended to keep the paper inside sterile and moist.
I do wonder: you let the paper air dry and then you put it in plastic, but the paper itself is allready pretty dry then.. so even with the foil around it, would it make such a big difference? The air itself is moisty too..
I do know that some samples, bacteria, are send on paper but they are send wet rather then dry, because send dry it doesnt revive that well.
(but not really easy, they are kept in little vials with some buffer or even media.. so I find it an odd way to use, you could also simple use slants that way... )