Fig. 1

A Readouts of a pHluorin2 assay using sensor strain L. innocua LMG2785/pNZ-pHin2^Lm and determination of antimicrobial activity in bacteriocin units. Controls: Green—negative control (LMBO buffer); red—two positive controls (left: LMBO containing 0.01% CTAB, right: M17 complex medium diluted fourfold in LMBO containing 0.01% CTAB). Orange: LMBO containing nisin at 0.128, 0.5, 1.25, 2.5 or 5 µg mL⁻¹ (from left to right). Blue/grey: exemplary cultivation supernatants obtained from L. lactis B1629. Blue: values below 50% threshold, grey: values above 50% threshold. 50% threshold is calculated from mean ratios of negative control and 5 µg mL⁻¹ nisin. Controls and standards were measured in technical triplicates. Sample dilutions were measured in unicates. B Plate layout of assay MTP used in automated pHluorin2 assay.