title: Effect of subinhibitory concentrations of ampicillin on the R plasmid transfer in Escherichia coli.
abstract: The effects of subinhibitory concentrations (sub-MICs) of ampicillin on R plasmid transfer in Escherichia coli were studied. Each donor strain culture was separated into two parts; one was mixed with a recipient strain culture for mating, the other was treated with the sub-MIC of ampicillin and then mixed with the recipient strain culture. In both cases the R plasmid transfer frequency was determined at 30, 60, 90 and 120 min of mating. Results showed that there exists a general decrease in the transfer frequencies under sub-MIC treatment (two plasmids did not transfer at all). The proportion of aggregates and the number of cells that compose them were not affected by the sub-MIC of ampicillin. Our study supports the idea that the changes induced in E. coli by sub-MICs of ampicillin did not affect the function of the surface structures responsible for aggregation but did affect the proteins implicated in DNA transfer, situated on the cell surface.
authors.affiliation: Department of Microbiology, School of Medicine, University of Seville, Spain.
authors.forename: J C
authors.initials: JC
authors.lastname: Palomares
authors.forename: R
authors.initials: R
authors.lastname: Prados
authors.forename: E J
authors.initials: EJ
authors.lastname: Perea
mesh_terms: D000667:Ampicillin / Q000494:pharmacology*; D003227:Conjugation, Genetic / Q000187:drug effects; D004926:Escherichia coli / Q000166:cytology / Q000187:drug effects* / Q000235:genetics; D011815:R Factors / Q000187:drug effects*; D013104:Spheroplasts / Q000187:drug effects
chemical_list: D000667:Ampicillin