Question

Why should you isolated plasmid after 12 to 16 hours of incubation?

Answer 1

Bacterium overnight culture usually means you grow a bacterium for 14-20 hours at 37'C. It doesn't matter how long the antibiotic last, the bacterium will reach its density plateau within 14-20 hours. Continue growing at 37'C will result a lot of dead cells in your culture. If you are not ready to use your overnight culture for days, just take it out the incubator, put it at 4"C and you can use it within two weeks.