Figure 5

Mathematical model and simulation results investigating the effect of bacterial density on oxygen dynamics. (A) The mathematical model represents the porous network using an angular pore network with the inset showing a cross-section through an unsaturated and saturated triangular pore depending on pore size with water films in blue including bacterial cells. Dual porosity containing a dense inner network representing the 1-mm glass beads and coarse outer network for the 3-mm glass beads are used. The visualized oxygen profile is a consequence of bacterial consumption combined with numerical diffusion containing a constant source at the aggregate periphery. (B) The measured gravity dynamics were used to simulate the reconfiguration of the aqueous phase during the parabola. (C) A dependency of oxygen dynamics on the bacterial cell density, strategically chosen to span the observed cell densities during the experiments, is evident and shown for a zero gravity parabola. (D) Quantification of mean residual oxygen concentration at the end of the parabola depending on gravity condition and bacterial densities. Due to the similar predicted wetted area between Lunar and zero gravity conditions (Fig. 4B), the predicted residual oxygen concentration depending on gravity conditions for these two scenarios is very similar.