Reuse of LB Amp plates? - (Nov/09/2007 )
The lab i'm getting my master's in is fairly new. He's been employed with the university for a year and this is his first time in the role of PI. Therefore, the lab is a little tighter on money than others. I'm working on a cloning protocol for miRNA's and have been having to borrow LB Amp plates from other labs (we don't want to spend the money on materials unti we're guaranteed it will work). So my question is, can I reuse my plates that have been in the incubator for 48 hours and have NO growth? What are the potential pitfalls of this? Thanks!
i am pretty new to all of this as well, but one major pitfall that i can see would be that amp is only stable for 3 days at 37C. so it seems like the amp might not be as effective when you go to grow up your plates. trust me, amp is so important, as i learned this week when i used old ampicillin and managed to purify DNA that was not my plasmid...TWICE.
Antibiotic degradation is the main danger and ampicilin also degrades fairly easily by hydrolysis of the beta lactam ring.
It is best not to reuse the agar. If you must, reuse the petri dish. Autoclave the petri dish (try it out, I am not sure if the plastic plates can take autoclaving, so you could stick to glass petri dishes which are fully recycleable.)
It is best not to reuse the agar. If you must, reuse the petri dish. Autoclave the petri dish (try it out, I am not sure if the plastic plates can take autoclaving, so you could stick to glass petri dishes which are fully recycleable.)
Interesting... I wasn't sure how long the amp was good for. What about spiking the plate with some more?? The agar is in plastic plates (got the plate already poured from another lab). I kinda doubt they will stand up to autoclaving... I suppose i'll be borrowing more, or talking the boss into buying some pre-poured ones....Thanks for the advice!
autoclaving plastic petri dishes at 121C tends to melt them beyond recognition. i autoclave them when i want to get rid of the colonies i am not using, and they melt all over the autoclave bag. bleaching the petri dish with a 10% bleach solution for at least 30 min would be a way to kill everything on the petri dish. but i think that petri dishes aren't that expensive, it is the ampicillin that is the more pricey item.
Right... and we don't have ANY of the materials needed to make our own plates... not the dishes, not the yeast or agar, not the antibiotics...zippo.... as far as I know, this is the only time we will be using plates so it might be cheaper to just go ahead and buy pre-poured ones than to buy all the materials needed to make them...Thanks!
It is cheaper to make your own LB plates. All the chemical and powders can be purchase from about any biochemical company like Acros, Alfa Aeser or Fisher.
• 10g/L Bacto tryptone
• 0.5g/L Yeast extract
• 10g/L NaCl
• 2ml/L of 1M NaOH
• 20g/L Agar
But since your lab appears to be using plates only this once, perhaps it is best to continue using plates made from your current source. To preserve the peace, propose a trade, your lab takes a few of their plates and your lab buys them a chemical of equal value.
Yeah.... our lab lets them use lab space for RNA work, we bought them some rtPCR supplies and everybody in the building uses our real time machine so I don't feel too bad... but I don't want to constantly be borrowing things from them, depleting their stock.....thanks!