Medium storage (1-2 years) can be done in agar stabs. You may keep them in the dark at room temperature.
Here is a freely available protocol:
http://www.auburn.edu/~santosr/protocols/EcolStabAgarProtocol.pdf
Always keep some DNA. For transformation you don't need very high efficient competent cells.
if you are asking about bacterial colony plates, then the cells will be viable for around 2 months, but it must be seal properly using paraffin film to avoid contamination. you have to keep glycerol stock of your cells at -80 or plasmid, which will be safer.
Best practice where I am is to only keep the plates for a week. I restreak from glycerol stocks each week for use. I've been bad and used them longer, as described above, but try to avoid it if possible.
You can only store for couple of weeks. It's very likely they will not be viable after 2-3 months.
- Badges
- Science topic