Preparation of LB agar plates

• Melt the LB agar in the 500 ml bottle in the microwave oven. Setting 300 W, unscrew the lid of the bottle the
• After the agar is completly melted place the bottle into a 55¡C water bath for 30 min.
• Add ampicillin to a concentration of 100 ug/ml. The stock (100 mg/ml) is 1000x concentrated.
• Mix without producing too many bubbles. Make sure that the ampicillin is uniformly distrubed
• poor the agar into 96 mm petri dishes
• After about one hour transfer transfer the plates to the cold room. Do not let stand at room temperature overnight. In contrast to yeast plates, LB plates should not be too dry.

Preparation of Ampicillin stock solution

Dissolve about 1 to 5 g of ampicillin (the powder is quite stable) in water to a concentration of 100 mg/ml.
• sterilize the solution with a 0.45 filter on top of a syringe
• directly fill in aliquots of about 1 ml into sterile eppendorf cups
• label the tubes with 'A' or 'Amp' on the lid of the tubes
• store the tubes in the box with the stock solutions in the -20¡C freezer