Question on bacterial culture - (Sep/28/2006 )
A starter 5ml bacterial culture is inoculated for 24 hrs. If i want to stop here for a while before going for larger culture/miniprep, how long can i keep this 5ml culture in 4oC?
if the antibiotics have not been exhausted by the 24hr incubation, if your sterile technique is okay and there is no contamination, if the 5ml culture is properly covered, and if the 4 Celsius cool room/fridge is clean and not producing tons of spores, and nobody tips the culture on the floor.
The 5ml culture will probably last 1 month. I wouldn't keep it for anymore then 2. (Although I have labmate who do keep their culture for 6months)
If you want to miniprep it for plasmid, you can spin the cells down and freeze the pellet at -20 degrees. To keep the culture for subculturing, then I agree with perneseblue, make sure there is no chance of contamination.
if possible, you'd better dilute your starter culture 1/500 or 1/1000 into selective LB medium(according to your midi prep protocol), grow for 12-16hrs. and centrifuge to harvest bacterial cells at conditions stated in your midi kit protocol. after removing supernatant, you can freeze your abcterial cell pellet at -20C for later use. this is where i usually stop during midiprep
for storage, I would streak it onto a plate, grow it O/N, then parafilm it and put at 4C for up to a month
when you are inoculating with an overnight culture, you need a healthy, heavy growth. I do not think it's wise to leave it sitting at 4C for weeks and then try to re-use it. there is a reason we use overnight cultures to spike larger batches.
Individual 50% glycerol stocks stored at -80oC.....forever........