Agar plates

Overview

This protocol is for preparing agar plates for bacterial colony growth

Protocol

  • Mix LB and Agar until thoroughly dissolved in a 2 L Erlenmeyer flask
  • Autoclave flask covered with tin foil (generally 121ºC for 15 minutes)
  • Cool to around 55ºC, warm to touch. Can keep in a water bath to keep from cooling too rapidly
  • Add antibiotic and swirl to mix
    • 1 ml Kanamycin (60 mg/ml)
    • 1 ml Ampicillin (100 mg/ml)
    • 1 ml Carbenicillin (60 mg/ml) Note: Carbenicillin is an Ampicillin analog and works like Amp
  • Spray pouring area thoroughly with 70% ethanol. Can have an open flame nearby to pass mouth of
  • Pour into 100 mm petri dishes until dish is 2/3 covered, then swirl to cover entire plate
  • 1 L of liquid agar is enough to pour approximately 70 x 100 mm petri dishes
  • Cover and let sit on desktop overnight
  • Store dishes upside down (agar on top) at 4ºC in sealed plastic bags
  • If Blue/White selection is required, spread 40 µl X-gal (50 mg/ml in DMSO) over the plates approximately one hour before spreading bacteria, and let them dry in a 37ºC incubator.

LB/Agar