1 does not act as a THA. Minimum inhibitory concentrations (MICs) of E. coli 25 922, BW25113 and siderophore TonB dependent transporter (TBDT) knock-out mutants, Δ3 and Δ6; Δ3 = ΔfhuAΔfecAΔcirA and Δ6 = ΔfhuAΔfecAΔcirAΔfepAΔfhuEΔfiu. Determined from spot-on-lawn bioassays under standard, iron depleted (+150 μM bipy) and iron replete (+2 mM Fe³⁺) conditions. Note the strain Δ6 is unable to grow under iron depleted conditions.

Organism	1 MIC/μg mL−1
		+bipy (150 μM)	+Fe3+ (2 mM)
E. coli ATCC 25922	256	256	≤1
E. coli BW25113	256	256	≤1
E. coli BW25113 Δ3	256	256	≤1
E. coli BW25113 Δ6	256	No growth	≤1