Pressure and temperature dependence of growth and morphology of Escherichia coli: Experiments and Stochastic Model

TL;DR

This study explores how pressure and temperature affect the growth and morphology of E. coli, revealing complex dependencies and proposing a stochastic model to explain phenotypic transitions at high pressures.

Contribution

The paper introduces a stochastic model for phenotypic switching in E. coli under high pressure, supported by experimental data on growth and morphology changes.

Findings

Division time increases exponentially with pressure above 30°C.

Phenotypic transition to elongating cells occurs sharply at high pressures.

Model accurately fits experimental data on phenotypic switching.

Abstract

We have investigated the growth of Escherichia coli E.coli, a mesophilic bacterium, as a function of pressure $P$ and temperature $T$. E.coli can grow and divide in a wide range of pressure (1-400atm) and temperature ($23-40^{\circ}$C). For $T>30^{\circ}$ C, the division time of E.coli increases exponentially with pressure and exhibit a departure from exponential behavior at pressures between 250-400 atm for all the temperatures studied in our experiments. For $T<30^{\circ}$ C, the division time shows an anomalous dependence on pressure -- first decreases with increasing pressure and then increases upon further increase of pressure. The sharp change in division time is followed by a sharp change in phenotypic transition of E. Coli at high pressures where bacterial cells switch to an elongating cell type. We propose a model that this phenotypic changes in bacteria at high pressures is an irreversible stochastic process whereas the switching probability to elongating cell type increases with increasing pressure. The model fits well the experimental data. We discuss our experimental results in the light of structural and thus functional changes in proteins and membranes.