Amp.res.Gram"-"Bacs without a plasmid?

benedik benedik at uh.edu
Fri Jul 10 14:48:28 EST 1998

In article <35A645BD.50002ADF at mbi.uib.no>
"Lab.1" <bjarte.furnes at mbi.uib.no> writes:

> I was searching for a plasmid in bacteria isolated from mice feces.
> Therefore I diluted feces and spread them on  LB plates containing
> Ampicillin. I got some colonies, but I didn`t get any amplification
> product using whole bacteria in a PCR with primers for the Amp.-gene.
> I tested the bacs on LB Amp. plates with Aztreonam discs, no growing
> near discs, so only Gramneg. bacs....Are there any Gramn. bacs Amp.
> resistent without a plasmid or are there other Genes making resistent
> than the betaLactamase Gene from pBR322 or are there inhibitors of PCR
> in Enterobacteriaceae or is a 10min 95C -step not sufficient to lyse the
> bacs....
> TIA,
> Chris

Yes, there are bacteria that will grow on standard amp plates. For
example Serratia marcescens, and many Pseudomonas strains. There are
certainly others that I don't know.

There are also amp resistance genes out there that are not identical to

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