Figure 1.
(a) Graphical representation of microbial exergy levels along division coordinates. Microbial exergy (EM) is augmented by the catabolic exergy within the harvesting volume (Ecat·[S]·Vharv, symbolized as dots in a circle surrounding the microbe). Reaching the threshold catabolic exergy (EM+E‡), the microbe is activated (a state denoted X‡), and an irreversible division process is triggered, associated with exergy dissipation (Edis=E‡−EM), resulting in two microbes. (b) Growth rate of E. coli as a function of glucose concentrations under aerobic conditions (Monod, 1942). The plain curve shows the fit of Equation (2) on the data. The dashed curve shows the fit of a Monod equation. A detail of the growth rate/concentration dependency at low substrate concentration is shown, illustrating that the mathematical expression of our law naturally accounts for the existence of an apparent substrate threshold concentration for growth.