Fig. 6

Ion availability as a trigger for aggregation/dispersion of bacteriophage T4—proposed mechanism in phage survival/infectivity cycles in (micro)-environment—the locally increased ions in proximity of bacteria serve as a cue, sensed by the phage, and converts into a quorum signal for re-organization. Infected (lytic phase) bacterium concomitantly releases cytosolic ions at high concentrations and phage in its dispersed form (left lower panel). Upon crossing the threshold gradient (range of 20 mM Na⁺, depicted as magenta circles) of monovalent cation, in low-ionic strength (water in soil) phage particles get clustered (aggregates), presumably to prolong bacteriophage survival (middle image panel). In contrast, in higher ionic concentration, like when immersed in zone of ionic fluxes contributed by live bacteria, bacteriophage particles disperse from clusters, as separate objects, to broaden the spread area and increase invasion events in proximity of the sensed host (right upper panel)