we always said overnight culture. what is the longest hours and shortest hour allowed for overnight culture?
what happened if too long?

i do not have problem about it, just want to clarify it.
hehe

cathy

hi
as i've read few times, it seems that overnight (bacterias you mean?) cultures should not exceed 16hours. If too long, bacterais arrest their growth and start to sleep, and lost plasmid (but the proportion of plasmid lost remain quite little...
i can't tell you more...

Hi Cathy,

Overnight is really what is convenient. It is dependant on you E. coli strain, your media, how heavy handed you are at streaking. Generally speaking however, for maximal efficiency of minipreps etc. it should not exceed 16 hours as you require the bacteria in log phase growth, therefore set up last thing, take off first thing is convenient. However, I've done 'overnight' cultures for four to six hours for some small scale minipreps, but I use 2xYT broth or Terrific broth which the E. coli like better instead of the stock standard L-broth which I use in the longer incubations.

Cheers,
Scott

It's adequate as a convenient incubation time, has no specific hours attached to it but should be consistent in your application. If growth phase is important, study the application and the growth curve of the microbe in question.

I'm not aware that plasmids would be shed if incubated a little longer. Any ref for that?

Actually it is a well known that the plasmid is often lost from the host strain should the culture be incubated for too long. This is caused by the lost of selection pressure once the selection agent (antibiotic) has been degraded by the bacteria culture.

A particular problem with penicillin type antibiotics which are degraded by beta-lactamases. This enzyme is a secreted into the growth media. Not a problem for tetracyclin selection, where the resistance gene product pumps the selection agents out of the cell without degrading the selection agent.

Of my head... you can look at this paper...
Plasmid instability in an industrial strain of Bacillus subtilis grown in chemostat culture

Reference please - and in the context of extended overnight incubation as is addressed in this thread. Culture any bug long enough and many changes may occur.

So why not just grow at a lower temperature? The growth rate (really doubling time) will be lower (that is, longer), so saturation and vegetative growth will take pace later.

Or is that being too simplistic?

swanny on Jan 26 2009, 11:25 PM said:

Come on guys - you've no idea cathy's application. Temperature may well be a critical variable - for all we know she's working with a dimorphic fungus.