Incubation period after heat shock at transformation--reason? - (Nov/24/2013 )

Hi all,

I remember my mentor told me that a one hour incubation period after heat shock is not needed if the vector is amp-resistant. However, if it is kanamycin resistant the incubation is necessary. Does anyone know the reason why? Is it because kanamycin kills all cells but amp only kills growing/dividing cells?

if im not mistaken, for transformation using amp as the selection, the bacteria does not need to express it, while antibiotic such as kanamycin, they need to be grow and incubated so that the bacteria can express the resistant gene. 

Ampicillin is bacteriostatic -- it halts growth, but does not kill the cell.  While not growing, the cell can still express the resistance gene, and will eventually become resistant and resume growth. Kanamycin inhibits protein production, and you cannot express the resistance gene without protein production. You can't get started on obtaining resistance without a period for protein expression prior to exposure to the antibiotic.

thank you so much to both of you!