Microwaving agar

15ml per plate; 6.4g LB agar in 200ml water in 500ml flask or bottle, makes 8-10 plates after microwaving for 2-10min. Make sure to keep a close eye on the agar while boiling! Lower microwave power if boiling to vigourously. Make sure to leave plenty of space in the container to avoid boiling over. Beaker or cylindrical bottle may be more resistant to boiling over than flask, because it gives more space for bubbles to pop.

References

• Sterile preparation of antibiotic-selective LB agar plates using a microwave oven. pdf
• Microwave sterilization of growth medium alleviates inhibition of Aggregatibacter actinomycetemcomitans by Maillard reaction products.
  • 600W, 90sec of boiling (of the broth only - agar was autoclaved!) was optimal for plating of A. actinomycetemcomitans.
• Microwave sterilized media supports better microbial growth than autoclaved media
  • 900W for 10min; 200ml in a 500ml screw capped glass bottle, reduced to 140ml after boiling. It took ~135 s for media to start boiling.
  • "Microwave sterilized media were found to support better microbial growth. Both bacteria and yeast were able to achieve higher cell density at a faster growth rate in microwaved media. Microwave treatment was found to be suitable for media of varying compositions. Better retention of nutrient quality in microwave treated growth media due to shorter heat exposure seems to be the major reason for better microbial growth in it."

• Microwave Oven in Microbiology Laboratory
  • 700W, full power for 5min. No growth after 24hr at 37C on blood agar or McConkey agar
  • "Microwave oven can safely be used in microbiology laboratory for preparation of media. The method is convenient, reliable, economical and reproducible. It saves time and the quality of media is superior as compared to media prepared by conventional autoclaving method"

• Would you Sterilise Growth Media With A Microwave?
  • "My take-home from this is that microwaves are are reasonably good at decontamination but more stubborn microorganisms (e.g. the spore-forming B subtilis) are not effectively disinfected. [...] I would not use this method for anything other than routine cultures and certainly not for slow growing organisms."

• imMedia™ – Fast food for E. coli
  • Commercial product by Invitrogen. Includes premixed antibiotics and "special heat stabilizers to make sure these heat-sensitive components stay active during and after microwave heating"
  • "Microwave on MEDIUM setting for 2-3 minutes. Then mix the solution and reheat for 30 second"