Flame sterilize an inoculating loop.
Use the sterilized loop to streak the surface of the agar with E. coli cells that have been transformed with the DNA plasmid of interest. Leave the plate inverted at 37 degrees C overnight. Be sure to also prepare a 5 mL culture in a 25 mL flask as the starter culture. Keep the flasks covered at all times to maintain sufficient sterility. Grow the cells to late log phase in a shaking incubator with vigorous shaking at 37 degrees C for 12-16 hours.