If I add the following ingredients of MS media
1- MS salts (+ Macro, micro and vitamins)
2- Sucrose
and adjust the pH of media 5.8 and keep it overnight at 4 C?
Can any body tell me that pH of the media will be changed or not during overnight at 4C?
Hi,
maybe you will find those articles interesting:
Article Stability of tissue culture medium pH as a function of autoc...
there is a mention about the pH variation and general acidification at room temperature which you should not experience if the temperature is around 4° C.
Article Effect of environmental and cultural conditions on medium pH...
The second article suggests the use of MES for stabilizing pH level.
Best
Dear Numan Mughal , what's the exactly purpose to leave the culture medium overnight at 4C? Does it means that the pH was adjusted before to store overnight? Anyway, I agree with Daniel Kunk , shouldn't be any problem for short time. However, consider the posibilities of microorganisms might growth despite culture medium don't contain sugar yet. In this case, great changes should be expected.
I appreciate all for their responses.
Daniel Kunk
I have checked the pH in the morning and the outcome was very surprising to me, the pH was decreased to 1.0 unit. I adjusted the pH 5.8 just before storing and in next morning I measured the pH (4.9) of the medium.Ricardo Julian Licea-Moreno Actually, the laboratory where I do work, allows me to work 8:00 AM - 4:00 PM and there are some bizarre rules for using autoclave machine. I just wanted to know that is it good or not for media, if I make media in the evening and store it and then autoclave in the morning to save media preparation time daily or whenever I want to?
However, I didn't find any microbial growth in the media by storing at 4C overnight.
Thank you for your responses again.
Dear Numan Mughal in your answer you mention an important detail, you "adjusted the pH 5.8 just before storing and in next morning I measured the pH (4.9) of the medium". I'm not chemist especialist and my college time is far away; however, I did homework (I think). Did you remember the Le Chatelier's principle? It states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change to reestablish an equilibrium. Thus, if you don't use an electrode that calibrate the pH in function of temperature, probably this change in the pH might be associated to the changes in temperature. Considering that conditions under you're working, it's possible that you don't have too much time to let rests the culture medium until it reachs an enviromental temperature similar to that you have before to store to 4CG. If it's the case, it sounds as probably hypothesis, I think.
Since you're not buffering your media, I can assure you that the pH will change quite dramatically.
Even in solidified medium, the pH will drop steadily from day to day.
You can check this by adding bromocresol purple to your medium, a pH indicator dye that doesn't interfere with plant development.
To prevent pH drift, lot's of labs are supplementing their growth media with a low concentration of MES (2.3 mM in our case). Sufficient yet mild buffering capacity to prevent large pH drift but leave plant growth unaffected.
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