They are not contaminated and have been kept at 4C. We have plates that were poured about 3 months ago (mannitol salt, LB, pseudomonas agar, etc) and want to know if they are usable and still selective or if we need to re-pour plates.
Hi:
Beside the occurrence of contamination, leaving agar plates for 3 months at fridge, make them dry out and unsuitable for bacterial cultivation and isolation.
As far as these are not contaminated and not dehydrated, you can use.
Generally poured plates should be used within a week. Post that it is generally not recommended for use. But if its not dehydrated u can use it.. good luck
High salt content plates generally dessicate faster.
If the plates were maintained at 4C, you can use them for 2 weeks (from the date of preparation). After 2 weeks you may see some dehydration, even at 4C. 3 months is too long and I would suggest making new plates.
In general practice plates poured should be used within one week of preparation. Since they are stored in such condition that there is no contamination, you can use the plates. Also prepare fresh plates and inoculate them along with old plates. Check for any difference in organism growth pattern. You will get to know the effect of using old plates for culture growth. Gud luck..
Plates should be used within two weeks since preparation if stored at 4C.
Yet the plates were maintained at 4C, these cannot be used for proper growth of the microbes as some sort of dehydration starts occurring after 2 weeks of plates preparation. prepare fresh plates for your research.
Good Luck,
Garima
Robin- 3 months is pushing it a bit. Most plates are OK for a month or 2 if wrapped and refrigerated. They may be OK (we used to keep Brilliant Green Plates for about 3 months), but its probably easiest to make new ones rather than go through some rigmarole of testing. Some media will not keep of course, but most are good for a month or six weeks at least.
If in doubt, throw it out! The rule works for just about any kind of leftovers. I've had some LB-Amp plates before that seemed to be selective after 3 months or so only to find that the rest of the batch they were in wasn't selective at all. I don't think all plates need to be made within a week - that often isn't practical - but anything more than 3 months is probably going to produce irregular results.
Harry is right. It's better to be safe. I don't usually keep my plates longer than 2 weeks.
Not more than3-4 days because water of media got evaporate which can hamper the growth of some meicrobes
Hi:
Beside the occurrence of contamination, leaving agar plates for 3 months at fridge, make them dry out and unsuitable for bacterial cultivation and isolation.
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