I have transformed competent E.coli cells with a plasmid. I then plate these on agar plate with antibiotic ampicillin. I did a mistake once where I overincubated the plates for 24 hours or so and noticed satellite colonies around the actual colony, probably from the secretion of enzyme that breaks down ampicillin allowing satellite growth.
I did a google search and I received advised from several saying it is perfectly OK to pick the single colonies and then grow it in liquid media with ampicillin as the satellite colonies derived cells wont be able to survive the liquid ampicillin later. But a thought comes to mind, wouldn't the actual colonies growing in liquid medium be able to secrete compounds that allow these satellite colonies to grow?
The secretion is the same but ampicillin in your liquid culture is keeping mixed all time. Since the secreted enzyme is very limited and is only able to degrade the ampicillin in the agar plate around the colony to certain concentration but not all ampicillin in liquid culture, the satellite colonies cannot grow up like the transform colonies if you are not extended your incubation time too long. Usually incubation for 16 hours at 37 degree shouldn't be any problem.
It all depends on your purpose. If you are going to inoculate a flask culture and grow it overnight, then it's OK, but if it is to be used for a long seed train ending in a 300-plus liter fermentor, then no, it's not.
@Huanting Liu: I've heard/read many times (although never seen the assertion backed up with actual data) that when a culture first gets noticeably cloudy, the amount of leaked periplasmic beta-lactamase is already enough to destroy all ampicllin present in the media within a few minutes
Yes it is true that there is sufficient beta-lactamase leaked into the culture to degrade the ampicillin in the medium. However the culture has already grown by then and has reached or is about to reach stationary phase. So no additional growth is occurring and most of the cells will have undergone selection and carry the plasmid. In plates there is ample room for growth elsewhere on the plates which is how the satellite colonies arise, but in liquid cultures.
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