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red dots in cell culture line? - (Nov/24/2013 )



Today I checked on my plates that I have been taking care of for the last two months or so. There were clearly visible red dots that appeared in the plate (without looking with a microscope.) After looking under a microscope, they looked much bigger compared to the "correct" cells. Does anyone know what these are? And why they are red...?


The red colour is probably a pigment of some sort, exactly which bacterium or fungus this is likely to be is hard to say, but it could be Serratia marcescens.  However, this will depend on the medium you are using, your location, temperature, etc.


are your "correct" cells still there? It is possible that the red is the precipitate of the Phenol Red containing medium, which could happen if the media partiatially dehydrates. Do you still have water in the tray of your incubator?

Is it possible that your media is just slowly drying out? Also if you can post a picture of your culture, that would help us to figure out what goes on.


thank you so much for your responses! unfotunately i got rid of the plate already. however there was still water in the tray of the incubator and the correct cells were still there