Hey all
I noticed that when I forgot to passage HeLa cells after 10 days the media colour had changed to yellow and I could see colonies everywhere. I gave multiple 1X PBS wash and passaged them. They took more time reach confluent but they are dong well.
Why did the media color change to yellow?
Please help
When cell culture medium is not changed frequently, and cells become too dense , acidic metabolites accumulate, turning the phenol red pH indicator yellow. You may have selected for the strongest adhering cells, so that the character of your cultures is now different. You may want to unfreeze a new aloquot of cells from an earlier cell culture passage number.
Most of the medium contains phenol red, which is a pH indicator. When the color of the medium changes from pink to yellow, it means that the nutrients in the medium are almost exhausted and the cell metabolites increase. If the culture medium is not replaced in time There will be fine shedding and death. Under normal conditions, if the culture medium turns yellow and the cells are congested, it is best to passage quickly.
Hello V H Krishna Prasad
Whenever you culture mammalian cells, you need to change the growth media every 2-3 days depending on the growth rate of the cells in culture. Mammalian cells show optimum growth at physiological pH (7.2-7.4). To know the status of the culture medium, the cell growth media is provided with the pH indicator namely, phenol red. When the phenol red color turns yellow it gives you an indication that the cells in culture have released a large amount of metabolic waste into the medium as growth and proliferation takes place, which has made the growth medium acidic and therefore the red color has changed to yellow.
So, it is a general practice to change the growth medium every 2-3 days depending on the growth rate of the cells in culture. Do not wait till the culture media turns yellow. This would be an incorrect practice as it would affect the health status of the cells. As rightly mentioned by Ellen A G Chernoff you will have to thaw a new vial if you are to perform further experiments with these cells. This is because even though they may be doing well, they are actually not fit for any invitro cell-based assay.
Best.
Thank you very much Malcolm Nobre , Evelyn Lee and Ellen A G Chernoff for your answers.
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