|MadSci Network: General Biology|
Hi Shelly, As an alternative to an autoclave, you could use a filtration apparatus for sterilization of liquids used to make the broth and add agar to this broth, then microwave the mixture to dissolve the agar. Assuming the agar is sterile and the filtration works appropriately, you should have sterile nutrient agar that can be poured into sterile Petri plates to solidify. If you don't have access to a vacuum and/or a sterile filter, you may be able to get away with just boiling the mixture in the microwave. However, this may not work, depending on what is contaminating your reagents. Regardless of your method, you should put a couple of prepared agar plates or media at 37C overnight to make sure no visible colonies of microorganisms form (a negative control). If all else fails, you could order pre-poured agar plates from one of many online lab supply stores. Good luck! Chris Reigstad P.S. It looks like various models of pressure cookers (essentially the same as an autoclave) are available for less than $100--this could be a valuable investment for your science classes at Glades Day School. Check with manufacturer regarding temperature (autoclaves should heat to at least 121C (250F) at 15 psi).
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