I have two plasmids, one as an indicator. The colonies show green or white but after streaking on a new plate they give mixed color colonies. The colonies are far away from each other in the first plate so the chance of contamination with other colonies is very low.
Expectation is to have more of one colony when streak one colony in a new plate but I am getting colonies with two colors streaked from one colony. What would be the reason in change in the color?
The antibiotic concentration on all plates is the same.
All colonies have both of the plasmids (indicator and suppressor)
Hello,
I have a few questions, what are the selectable markers on your plasmid? does the antibiotic that you added exert selection pressure and help maintain the plasmid? If yes, why did you have white colonies in the first Petri dish (ie colonies that did not receive the plasmid)?
Afterwards, if you have white colonies, potentially your bacteria have lost the plasmid because there is no selection pressure.
You need to better explain what you did. Do you have a mixture of strains each with one plasmid? Or two plasmids in one strain? And why green?
Sofiane Benyamina
Hello,
The selection is made by two antibiotics which are preset in two plasmids transported.
My first assumption was the same, that plasmids are not in the white colonies or the green colonies have one plasmid. However, I checked the presence of plasmids with PCR and it showed both white and green colonies have both of the plasmids.
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