Actually I wanted to know that whether UV degrades or changes the nutrient agar?
I am a bit surprised by this lengthy discussion.
Having prepared media during a whole lifetime of microbiology, I don't see why you want to put plates under UV.
Pour plates under aseptic conditions and control a sample of your prepared media for sterility. Prolonged exposure of prepared media to light, especially UV light, will degrade many nutrients and ingredients and should be avoided.
Dear Hamed,
You can use UV for solidification of agar plates or for drying of them, except of ones with antibiotics, because different antibiotics can degrade under UV light. But don't expose plates for a long time.
Why do you want to keep the plates under UV, for sterilisation purposes? Many vitamines are sensitive to light, e.g. vitamin A, B2, B6 and B12. Also, depending on the kind of plastic petri dishes you are using, there might be changes to the plastic, leaking of free radicals e.g. So, I wouldn't really do it, especially not for long-term storage, since they will also dry out.
I routinely pour agar plates under the laminar flow hood, and dry them there with lights off/no UV. Afterwards, they are placed upside down in a plastic bag and stored in the fridge/cold room (i.e. with the lid on the bottom, agar side on top, to avoid condensed water dripping back onto the agar). They can be kept for a while (about 4 weeks).
Autoclaving Nutrient Agar at 121 degree C for 15mins. at 15lbs. pressure and pouring it inside a Laminar Air Flow cabinet is enough to prevent contamination. Pre or Post solidification exposure of NA plates to UV light may be detrimental for the peptidic constituent of NA due to Photoalteration effect.
You may loss certain biomolecules like antibiotics and vitamins essentially needed for biological growth. It is not recommended to do so.
If you are confused, then it is better to avoid using UV for NA plates sterilization. Just dry them in the laminar hood while keeping UV off but the blower on. If you have antibiotics in your agar , then it is best no to use UV. What i do is, dry the plates and then spread the antibiotic on the solidified plate. Unused plates should not be stored for long. If you have to store it, then it is better you do not expose ur plates to UV at all.
As per my knowledge is concern nothing wrong in keeping the NA plates for Ultraviolet exposure.........
You can keep nutrient agar plates under UV but not for very long periods.
I completely agree with the colleague Maria when she asked firstly why do you want to keep the plates under UV? If the plates were poured under aseptic conditions facing the problem of contamination is rare. I just advice to keep the poured plates without culturing (after drying) for 18 hr at room temperature to be sure that it is sterile , you have to discard any plates showed any sign of growth. I'm not sure that exposure of plastics to UV leaking free radicals (free radicals may be come from water content of NA). I just like to attract the attention that direct exposure for long time for short wave UV is dangerous especially for skin, hair and eyes. I agree with Maria with the method she followed for drying and keeping the poured plates. At the same time I ask Mr. Bhaskar why he spread the antibiotics on the solidified plates? If he like to test for antibiotic resistance, application of Bio-discs is recommended or addition of antibiotics to the media at 45 - 48 degree C before pouring in the plates.
Yes you can put nutrient agar plates under UV light (during and after solidification), but it should be free from any kind of culture, antibiotics, and vitamins.
Yes you can put your antibiotic less Nutrient agar plates under uv light. There is no harm in this. I always use like this and never got any thing wrong..so no doubt about that..
I just have a comment on. Chhetri's answer, he mention that he always put the plates under UV and never got any thing wrong !! Have you a comparison data that you depend on to reach the conclusion? You know that there is a part in Standard Methods by American Public Health Association on Quality Assurance/Quality Control please kindly read it carefully before you reach the conclusion that no doubt about that ! Ref: Standard methods for the Examination of Water and Wastewater. 2005. American Public Healthe Association, Washigton, DC.
I would like to add that some industries need water completely free from organics the application of UV A as final water treatment is the way to have water completely free from organics. That is about UV A but for sterilization usually UV C is used but at the same time the UV lamps never produce 100% UV C. To be sure that there is no effect please design experiments and consider the quality control quality assurance program that I mentioned to reach the wright answer. Hope all success for you.
I am a bit surprised by this lengthy discussion.
Having prepared media during a whole lifetime of microbiology, I don't see why you want to put plates under UV.
Pour plates under aseptic conditions and control a sample of your prepared media for sterility. Prolonged exposure of prepared media to light, especially UV light, will degrade many nutrients and ingredients and should be avoided.
Yes. UV will definitely degrade the nutrient agar. To what degree, depends on a number of factors such as exposure time, dosage, wavelength, thickness of the agar, etc. One important factor to take into consideration: is there a barrier between the agar and the UV. Glass like borosilicate tends to filter some UV esp. those below 300nm.
I believe there should not be aplroblem, as long as you do not leave them for long periods
Plates already steriled and no need to UV light. You should use biological hood and Bunsen burner duration of solidification.
Dear sir , it is the good idea.u can keep the plates under UV light not more than 25 mins and switch on the flow after plating because it will be more dry after 25-30mins.
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