Simulation of oxygen gradients and addition of alternative electron acceptors suggest that oxygen depletion triggers collective hyperpolarization.

(A) Time lapse of simulated oxygen concentration field. Color code: oxygen concentration . Black circles: colony radius R(t). Red circles: radial distance riso of the iso-concentration line at concentration c*. Scale bar: 20 μm. (B) Simulated propagation of the riso circle corresponding to c* = 0.8c0 (curves from simulations are shown for the uptake parameters ε = 0.1, 0.5, and 0.9). (C) Experimental propagation of transient hyperpolarization shells. (Means and standard errors over 20 colonies.) (D) Time lapse of TMRM signal for a colony (strain wt*, Ng150) in static culture supplemented with 5 mM of NaNO2. Scale bar: 10 μm. (E) Time lapse of TMRM signal for a colony (strain wt*) in static culture without supplement. Scale bar: 10 μm. (F) Time lapse of TMRM signal for a colony (strain wt*) in static culture supplemented with the oxygen scavenging system PCA and PCD (see S1 Data for raw values). Scale bar: 5 μm. PCA, protocatechuic acid; PCD, protocatechuate-dioxygenase.