title: The lag-phase during diauxic growth is a trade-off between fast adaptation and high growth rate.
abstract: Bi-phasic or diauxic growth is often observed when microbes are grown in a chemically defined medium containing two sugars (for example glucose and lactose). Typically, the two growth stages are separated by an often lengthy phase of arrested growth, the so-called lag-phase. Diauxic growth is usually interpreted as an adaptation to maximise population growth in multi-nutrient environments. However, the lag-phase implies a substantial loss of growth during the switch-over. It therefore remains unexplained why the lag-phase is adaptive. Here we show by means of a stochastic simulation model based on the bacterial PTS system that it is not possible to shorten the lag-phase without incurring a permanent growth-penalty. Mechanistically, this is due to the inherent and well established limitations of biological sensors to operate efficiently at a given resource cost. Hence, there is a trade-off between lost growth during the diauxic switch and the long-term growth potential of the cell. Using simulated evolution we predict that the lag-phase will evolve depending on the distribution of conditions experienced during adaptation. In environments where switching is less frequently required, the lag-phase will evolve to be longer whereas, in frequently changing environments, the lag-phase will evolve to be shorter.
authors.affiliation: University of Kent, School of Computing, Canterbury, CT2 7NF, UK.
authors.forename: Dominique
authors.initials: D
authors.lastname: Chu
authors.affiliation: University of Kent, School of Computing, Canterbury, CT2 7NF, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Barnes
mesh_terms: D018533:Biomass; D050260:Carbohydrate Metabolism; D003198:Computer Simulation; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D010770:Phosphotransferases / Q000378:metabolism
chemical_list: D010770:Phosphotransferases