Protocol Online logo
Top : Forum Archives: : Molecular Biology

How long does it take E. coli to grow on plates at 30 degrees - transformation (Jun/03/2005 )

I am attempting to transform Max effiency stbl2 e. coli cells from invitrogen with a plasmid roughly 10 kb in length. I have completed all previous steps, and am now waiting for growth on my selective plates. I placed the plates at 30 degrees ~ 36 hrs ago, and still have zero colonies. My positive control (puc19) plate grew great, but that was placed at 37 degrees and contained a much smaller plasmid. Has anyone had success with colonies growing after 36 hrs of incubation at 30 degrees?


Hi Amysue
sorry to diaaspoint you but in my experience E. coli grows perfectly well at 30 degrees and even at room temp...i wouldn't throw them out just yet, but i wouldn't expect anything either...


usually i put plates overnight at 37° or on the bench for two days (for week ends). I've noticed that there's no great difference between bench / 30°.
i would suggest to wait little more (1day?) or do an other experiment. Maybe transformation didn't occur at all. sad.gif



in my experience colonies which grow on antibiotic plates after more than two
days are never transformants. I was never able to isolate a plasmid out of these
strains and I think it is a waste of time to do any further experiments with them.
Additionally, I was usually not able to observe any difference between plates
incubated at 30°C or 37°C, except during switches from LB to Minimal Medium,
then you have to expect a lag-phase of about one day.