Origin of temperature dependence of bacterial growth rate: Analogy with the viscosity of glass-forming liquids in inorganic materials

Abstract

Based on a recent suggestion that the bacterial cytoplasm has a property similar to glass-forming liquids, we have proposed a new relation for the temperature dependence of the bacterial growth rate, k = k0exp[–Ea/kB(T–Tc)] in the lower temperature range, where k0 is a constant, Ea is the activation energy (eV), kB is the Boltzmann constant, T is the absolute temperature (K), and Tc is the characteristic (frozen-in) temperature (K), resembling the temperature-dependent fluidity (inverse viscosity) observed in glass-forming liquids in inorganic materials. This monotonic behavior of bacterial growth breaks down at higher temperatures, that is, k decreases rapidly with T. This may be attributed to a rapid increase in the physiological cytoplasmic concentration above the critical temperature Tm. The finding on the temperaturedependent bacterial growth rate is analogous to that observed in glass-forming liquids in non-living inorganic materials.

Keywords

• bacterial growth rate
• glass-forming liquid
• glass transition
• viscosity
• free volume