Protocol Online logo
Top : New Forum Archives (2009-): : Molecular Biology

More cells in an antibiotic plate than in a plate without antibiotic???? - (Nov/11/2011 )


these days I'm checking plasmid stability in our working cell bank. I plate the cells on four different plates: TB, TB+kanamicyn, TB+IPTG and TB+IPTG+kanamycin. Curiously, I always found more cells in the TB+kanamicyn than in the TB plates. Why? Some idea?? because I would expected just the contrary...

Thank you in advance!!!


interesting :)

maybe it is due to your dilutions that you make for plating ...or maybe due to the fact that you chill the agar more in the case of the TB+Kan (since you pay more attention to its temperature because of the kan) ...only you know what you are doing exactly.

But think about all the steps you do! ...i would assume it is some handling issue!

Best regards,


Thanks!!! I also think it is due to something related with the plating but I don’t know what. When I plate I use the same dilution and I prepare the media in the same way. I wait until media reach 60 ºC to add the phosphate buffer and then I prepare the plates and/or add the antibiotic.
Well, thanks for your suggestions. I going to thinking about it.

Best regards,