Protocol Online logo
Top : Forum Archives: : Molecular Cloning

Contamination from satellite colonies - (Mar/26/2007 )


I'm wondering if satellite colonies (on agar plates after transformation) might contaminate the DNA preparation afterwards?!?
If I pick a colony that is surrounded by satellites I can't completely rule out the possibility that I also touch one of the satellites. However, in my opinion those cells shouldn't grow in the LB media afterwards since it's supplemented with ampicillin right? Furthermore, purifying the DNA from the cell suspension should only yield plasmid DNA, not genomic DNA from the satellites.
Am I right?



in my experience, satellite colonies always die if you grow them in broth using the same antibiotic that was on the plate. By definition, satellite colonies chould be susceptible or they wouldn't be satellites. You're not likely to get problems unless your antibiotics are old or degraded, or you shake your lysed cells too hard during the plasmid prep and get genomic DNA carrying over.