Extended Data Fig. 8: Phytoplankton exudation rate affects bacteria-phytoplankton distances and bacterial ‘trapping’.

(a) Bacteria-phytoplankton distance is strongly affected by phytoplankton exudation rate. These data show the distance to the nearest hotspot, averaged over time (3 h co-incubation) and bacterial population (500 cells), as a function of DOM leakage rate L (pmol hr⁻¹). Results are shown for three different phytoplankton concentrations, 10³ (dotted), 10⁴ (dashed), 10⁵ cells ml⁻¹ (solid), and for three different bacterial mutants: chemotactic WT (blue), non-chemotactic ∆cheA (orange), non-motile ∆fliC (red). (b) Bacteria-phytoplankton trapping statistics. These data show the percentage of bacterial cells that are situated within 35 μm of a phytoplankton cell (phycosphere), as a function of DOM leakage rate L (pmol hr⁻¹). For each datapoint, results have been averaged over time (3 h co-incubation) and bacterial population (500 cells). Results are shown for three different phytoplankton concentrations, 10³ (dotted), 10⁴ (dashed), 10⁵ cells ml⁻¹ (solid), and for three different bacterial mutants: chemotactic WT (blue), non-chemotactic ∆cheA (orange), non-motile ∆fliC (red).