2.2.2. Spot on Lawn Antibacterial Assay

The spot-on-lawn assay was performed to evaluate the antibacterial potential of 22 selected isolates; two isolates of the same species were selected based on the source of origin and incubation conditions they were isolated from (Table S2). This method was adapted from Crowley et al. [24]. Briefly, 2 µL of 24 h grown culture isolates were spotted onto two MRS agar (Oxoid) plates, which were incubated at 37 °C for 48 h. The plates were subjected to UV treatment for 45 min. Indicator strains at concentrations of 10⁵ to 10⁶ CFU/mL were mixed with 0.8% w/v semi-solid agar and poured onto the MRS agar plates containing the isolates. The plates were incubated for a further 24 h, after which zones of inhibition surrounding the LAB colony were measured. The zones were scored against the following arbitrary scale: no inhibition observed, −; 9–15 mm zone of inhibition, +; 16–22 mm zone of inhibition, + +; 23–29 mm zone of inhibition, + + +; ≥30 mm zone of inhibition, + + + +. If the zone of inhibition was present, the ‘+’ symbol is presented whereas if the zone of inhibition was hazy, this symbol will be color-coded red. Assays were performed at least in triplicate.