LB Agar Plates
by Karmella Haynes, 2012
- Personal Protective Equipment (PPE) - lab coat, disposable gloves
- ~40 clean, sterile petri dishes (pr "plates"), packed in plastic "sleeves" per 1 liter of LB agar
- LB Broth powder (Sigma L3022)
- Bacteriological Agar
- 1N NaOH
- Two clean and sterile 1000 mL glass flasks
Make LB Agar - these instructions are for 1 liter
- Put on your PPE.
- Fill a 1000 mL graduate cylinder with deionized water (from the sink)
- Weigh out 20 g of LB Broth powder on the balance.
- Add the LB powder to the water in the cylinder.
- Weigh out 15 g of Bacteriological Agar.
- Add the Bacteriological Agar to the mixture in the cylinder.
- Use a 1000 μL micropipette to add 1000 μL 1N NaOH to the mixture.
- Swirl the mixture for a few seconds.
- Fill the cylinder up to 1000 mL with deionized water (from the sink).
- Get two clean, sterile 1000 mL glass flasks from the shelf. Remove the foil caps and set them aside
- Carefully cover the cylinder with a large square of parafilm. Make sure the seal is tight.
- Cover the opening with your gloved hand and invert the cylinder several times to mix the solution.
- Quickly and carefully fill each flask up to the 300 mL mark. Cover the cylinder again and invert to mix.
- Quickly and carefully fill each flask up to the 400 mL mark. Swirl the cylinder to mix.
- Quickly and carefully fill each flask up to the 500 mL mark.
Set up the plates to be filled
- Cover the bench top with bench paper
- Get a stack of plates and cut open the very top of the sleeve. Do not rip apart the sleeve. You will need this to store the finished plates.
- Take the plates out and stack them in sets of five, lid-side-up