The Effect of R Factor Transfer on Bacterial Growth Rates an in Vitro Study

Abstract

It has been studied whether R factor transfer had an inhibitory effect on the growth rate of Escherichia coli in mixed cultivation. A total of 39 antibiotic resistant E. coli strains were grown together with E. coli K12 W 3132 as prospective recipient. Thirteen crosses turned out successfully. When comparing generation times for these crosses with those of negative crosses no difference could be demonstrated. This, however, does not exclude that R factor transfer impairs bacterial growth capacity at a level which can not be detected in a short-term experiment.

Sammendrag

Det er undersøgt, hvorvidt overførsel af R faktor er bar en hæmmende virkning på E. coli’s væksthastighed i blandingskulturer. Ialt 39 antibiotikaresistente E. coli stammer isoleret fra svin er dyrket sammen med E. coli K 12 W 3132 som potentiel recipient. I 13 af disse krydsningisforsøg skete overførsel af R faktorer. En sammenligning af generationstider for positive og negative krydsninger viste ingen forskel. Det kan imidlertid ikke udelukkes, at R faktor overførsel hæmmer bakteriers væksthastighed på et niveau, som ikke lader sig påvise i et kortvarigt forsøg.