I need to test different pH conditions for a S. cerevisiae culture in different growth media (YPD, molasses and so). Is it ok if I first set the pH of the media using citrate buffer and then sterilize the media by autoclaving? I know that this process can (and will surely) affect the final pH of the media, but I cannot think of any way of adjusting the pH after autoclaving and do it in sterility conditions. Any suggestions?
Hi Jesús. there's no problem in autoclaving citrate buffer. Just check that the buffer does not change the nutritional conditions. I mean, for many species, citric acid is a carbon source. However, the media you named are rich enough and I don't think that the buffer would make a big difference. Keep in mind that autoclaving can slightly change the pH but it shoul go back to the values you had befor heating.
Harald Kühnel
thank you! I also thought about that, but my problem is monitoring the pH of the media once it's sterile (I can't sterilize my pH-meter).
Harald Kühnel
I have to test a wide range of parameters before going into a biorreactor, but surely it would solve this problem.
You can use filters to sterilize the buffer solution. You do not need to autoclave it after adding it to the medium. Alternatively, you can prepare the medium as a duplicate in different batches and can use this one as a control group to which you are supposed to know how much to be added for the next time.
Furkan Aydin this latter idea is a really good one, thank you so much.
Hello! I prepare media for my job, including LOTS of yeast media. We always adjust the pH of any SD/SC medium to 5.8 prior to autoclaving - the sterilization process will not affect the pH. We also autoclave yeast nitrogen media, YEA and YEA+Sup mixtures, and have never had any issues with the autoclave affecting the pH. We use HCl and NaOH solutions to adjust pH, occasionally citric acid solution instead of HCl, any of those should work fine. Happy researching!
- Badges
- Science topic
- Similar topics
- Biological Science
- Biochemistry
- Biochemical Techniques
- Analytical Chemistry
- pH