I'm using Stellar Chemically competent cells to express GEVI plasmids. We grow the transformed cells on regular Amp plates, then pick individual colonies to grow in 2XYT media. After their growth, when we spin them down some of the wells are purple. This isn't an uncommon occurrence at this point. We're still able to extract DNA it seems, but we don't know why some of the bacteria are turning purple? We thought possibly it could have something to do with the red and green fluorophores in the plasmid, but that doesn't seem like it would make sense, seeing as they're purple under regular light. Any ideas why this may be happening?
Hello Laurel Kastner
I have seen red pellets of E. coli transformed with a vector containing mCherry fluorescent protein in my lab. In our case was because the promoter that we cloned was recognized by the bacteria. In any case, all the bacteria in our pellets were red, but yours seems to have a white part. Try to separate your bacteria in solid media and culture both, the purple and white colonies, to see if both harbors your plasmid or only one of them.
A lot of red fluorophores tend to turn colonies magenta or purple-ish instead of red by ambient lighting. The fluorescence color is not necessarily how it will appear by eye. There's a lot of variables that go into how intensely the color develops also.
- Badges
- Science topic