LB + Amp. preparation - Recipes (Feb/03/2006 )

Hello everyone...

We are running low on amp. within our lab; indeed, we only have one 1.5 ml tube of 25 mg/ml of amp left. I was wondering how can I prepare LB + Amp plates without exhausting my complete supply? What should the final concentration be within the agar prep? I will also need some of the stock to set up individual LB broth + Amp tubes for cloning. Thanks for everyone's help here...

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you should prepare 10 plates, of 15 mL each with 100 ug/mL of ampicillin. it will use 600 uL of your stock and you still have some to prepare some tubes.

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Thanks for the quick response! Would you suggest that I maintain the same concentration of ampicillin in the individual tubes also?

Also, I've seen some protocols stating that 50 ug/ml of ampicillin could be sufficient. The only reason I bring this up is because I wish to make probably make 16-20 plates...

Thanks again!

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plates can be prepared with low to 50µg/ml final concentration. but take extra cares to prepare them and to spread your bacterias on it.

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What about preparing 400 ml LB agar with 50 ug/ml (should be more than enough for 18 plates)
this way you only use 800 ul of your 25mg/ml Ampicilin stock.

Then you still have 700 ul stock left that you can use to prepare 350 ml LB Amp.

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If you make plates @ 50 µg/ml do not let your colonies on there for too long. Just perform transformation late enough in the day and be back early enough next morning otherwise you can find some satellite colonies...

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Thank you everyone for the responses! I love this site, especially the forum.

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