title: Plasmid copy number noise in monoclonal populations of bacteria.
abstract: Plasmids are extra chromosomal DNA that can confer to their hosts' supplementary characteristics such as antibiotic resistance. Plasmids code for their copy number through their own replication frequency. Even though the biochemical networks underlying the plasmid copy number (PCN) regulation processes have been studied and modeled, no measurement of the heterogeneity in PCN within a whole population has been done. We have developed a fluorescent-based measurement system, which enables determination of the mean and noise in PCN within a monoclonal population of bacteria. Two different fluorescent protein reporters were inserted: one on the chromosome and the other on the plasmid. The fluorescence of these bacteria was measured with a microfluidic flow cytometry device. We show that our measurements are consistent with known plasmid characteristics. We find that the partitioning system lowers the PCN mean and standard deviation. Finally, bacterial populations were allowed to grow without selective pressure. In this case, we were able to determine the plasmid loss rate and growth inhibition effect.
authors.affiliation: Laboratoire Jean Perrin, FRE 3231 CNRS-UPMC, Paris, France. jerome.robert@lps.ens.fr
authors.forename: Jérôme
authors.initials: J
authors.lastname: Wong Ng
authors.forename: Didier
authors.initials: D
authors.lastname: Chatenay
authors.forename: Jérôme
authors.initials: J
authors.lastname: Robert
authors.forename: Michael Guy
authors.initials: MG
authors.lastname: Poirier
mesh_terms: D000465:Algorithms; D002876:Chromosomes, Bacterial; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development; D005434:Flow Cytometry; D005453:Fluorescence; D018628:Gene Dosage; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics; D016014:Linear Models; D046210:Microfluidic Analytical Techniques; D010957:Plasmids / Q000235:genetics*; D016133:Polymerase Chain Reaction; D013696:Temperature; D013997:Time Factors
chemical_list: C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins