title: Precise determinations of C and D periods by flow cytometry in Escherichia coli K-12 and B/r.
abstract: The C and D cell cycle periods of seven Escherichia coli K-12 strains and three E. coli B/r strains were determined by computer simulation of DNA histograms obtained by flow cytometry of batch cultures grown at several different generation times. To obtain longer generation times two of the K-12 strains were cultivated at several different dilution rates in glucose-limited chemostats. The replication period (C period) was found to be similar in K-12 and B/r strains grown at similar generation times. At generation times below 60 min the C period was constant; above 60 min it increased linearly with increasing generation time. The period from termination of replication to cell division (D period) was more variable. It was much shorter in B/r than in K-12 strains. Like the C period it was relatively constant at generation times below 60 min and it increased with increasing generation times at longer generation times. In glucose-limited chemostats good correlation was found between D periods and generation times, whereas batch cultures exhibited carbon-source-dependent variations. Chemostat cultures showed cell cycle variations very similar to those obtained in batch cultures. These flow cytometric determinations of cell cycle periods confirm earlier determinations of the C period and establish that the D period also varies with generation time in slowly growing cultures. In addition they extend the range of growth rates at which cell cycle periods have been determined in E. coli K-12.
authors.affiliation: Section of Molecular Microbiology, BioCentrum - DTU, Technical University of Denmark - DTU, Building 301, DK-2800 Lyngby, Denmark.
authors.forename: Ole
authors.initials: O
authors.lastname: Michelsen
authors.affiliation: Department of Microbiology, E. C. Slater Institute, BioCentrum Amsterdam, University of Amsterdam, 1018 WS Amsterdam, The Netherlands.
authors.forename: M Joost
authors.initials: MJ
authors.lastname: Teixeira de Mattos
authors.affiliation: Section of Molecular Microbiology, BioCentrum - DTU, Technical University of Denmark - DTU, Building 301, DK-2800 Lyngby, Denmark.
authors.forename: Peter Ruhdal
authors.initials: PR
authors.lastname: Jensen
authors.affiliation: Section of Molecular Microbiology, BioCentrum - DTU, Technical University of Denmark - DTU, Building 301, DK-2800 Lyngby, Denmark.
authors.forename: Flemming G
authors.initials: FG
authors.lastname: Hansen
mesh_terms: D002453:Cell Cycle; D002455:Cell Division; D003198:Computer Simulation; D003470:Culture Media; D004269:DNA, Bacterial / Q000032:analysis; D004926:Escherichia coli / Q000166:cytology* / Q000254:growth & development*; D005434:Flow Cytometry / Q000379:methods*; D008954:Models, Biological
chemical_list: D003470:Culture Media; D004269:DNA, Bacterial