Light-Harvesting Mechanism of Bacteria Exploits a Critical Interplay between the Dynamics of Transport and Trapping

Light-harvesting bacteria Rhodospirillum photometricum were recently found to adopt strikingly different architectures depending on illumination conditions. We present analytic and numerical calculations which explain this observation by quantifying a dynamical interplay between excitation transfer kinetics and reaction center cycling. High light-intensity membranes exploit dissipation as a photoprotective mechanism, thereby safeguarding a steady supply of chemical energy, while low light-intensity membranes efficiently process unused illumination intensity by channeling it to open reaction centers. More generally, our analysis elucidates and quantifies the trade-offs in natural network design for solar energy conversion.