title: Individuality and universality in the growth-division laws of single E. coli cells.
abstract: The mean size of exponentially dividing Escherichia coli cells in different nutrient conditions is known to depend on the mean growth rate only. However, the joint fluctuations relating cell size, doubling time, and individual growth rate are only starting to be characterized. Recent studies in bacteria reported a universal trend where the spread in both size and doubling times is a linear function of the population means of these variables. Here we combine experiments and theory and use scaling concepts to elucidate the constraints posed by the second observation on the division control mechanism and on the joint fluctuations of sizes and doubling times. We found that scaling relations based on the means collapse both size and doubling-time distributions across different conditions and explain how the shape of their joint fluctuations deviates from the means. Our data on these joint fluctuations highlight the importance of cell individuality: Single cells do not follow the dependence observed for the means between size and either growth rate or inverse doubling time. Our calculations show that these results emerge from a broad class of division control mechanisms requiring a certain scaling form of the "division hazard rate function," which defines the probability rate of dividing as a function of measurable parameters. This "model free" approach gives a rationale for the universal body-size distributions observed in microbial ecosystems across many microbial species, presumably dividing with multiple mechanisms. Additionally, our experiments show a crossover between fast and slow growth in the relation between individual-cell growth rate and division time, which can be understood in terms of different regimes of genome replication control.
authors: Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom.|Biophysics Program, Stanford University, Stanford, California 94305, USA.
authors: Andrew S
authors: AS
authors: Kennard
authors: Dipartimento di Fisica and INFN, University of Torino, V. Pietro Giuria 1, Torino, I-10125, Italy.
authors: Matteo
authors: M
authors: Osella
authors: Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom.
authors: Avelino
authors: A
authors: Javer
authors: Department of Ecology and Evolution, University of Chicago, 1101 E 57th st., Chicago, Illinois 60637, USA.|Dipartimento di Fisica e Astronomia 'G. Galilei', Università di Padova, via Marzolo 8, Padova, 35131, Italy.
authors: Jacopo
authors: J
authors: Grilli
authors: FOM Institute AMOLF, Science Park 104 1098 XG Amsterdam, The Netherlands.|Laboratoire de Biochimie, UMR 8231 CNRS/ESPCI, École Supérieure de Physique et de Chimie Industrielles, 10 rue Vauquelin, 75005 Paris, France.
authors: Philippe
authors: P
authors: Nghe
authors: FOM Institute AMOLF, Science Park 104 1098 XG Amsterdam, The Netherlands.
authors: Sander J
authors: SJ
authors: Tans
authors: Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom.
authors: Pietro
authors: P
authors: Cicuta
authors: Sorbonne Universités, UPMC Univ Paris 06, UMR 7238, Computational and Quantitative Biology, 15 rue de l'École de Médecine Paris, France.|CNRS, UMR 7238, Paris, France.
authors: Marco
authors: M
authors: Cosentino Lagomarsino
mesh_terms: D002455:Cell Division; D049108:Cell Enlargement; D048429:Cell Size; D004926:Escherichia coli / Q000166:cytology* / Q000502:physiology*; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D013995:Time