Fig. 1: Schematic representation of the cellular processes.
From: Quantifying nitrogen fixation by heterotrophic bacteria in sinking marine particles
It shows how fluxes of carbon (C), \({J}_{{\rm{C}}}\) (solid lines), fluxes of nitrogen (N), \({J}_{{\rm{N}}}\) (dotted lines), and electron acceptors (\({{\rm{O}}}_{2}\), \({{{\rm{NO}}}_{3}}^{-}\), and \({{{\rm{SO}}}_{4}}^{2-}\); red dashed line) are combined (blue ellipse) to determine growth rate after paying the cost of respiration (brown explosion). Triangle symbols represent the functional responses for the uptake mechanisms and diffusive inflow of \({{\rm{O}}}_{2}\), \({{{\rm{NO}}}_{3}}^{-}\), and \({{{\rm{SO}}}_{4}}^{2-}\). \({J}_{{\rm{tot}}}\) represents respiration that includes costs of uptake and mobilization of resources for synthesis, construction/maintenance of structure, and ectoenzyme production. The ellipse represents the synthesis of biomass from the available C, N, and electron acceptors following Liebig’s law of the minimum. Any excess assimilated C or N is excreted from the cell. µ represents the division rate. The black dashed-dotted line represents the regulation of \({{\rm{N}}}_{2}\) fixation to optimize growth rate and the red dashed-dot line represents the regulation of respiration by electron acceptors.
