Motility plate assay

Motility assays were assessed on 0.35% w/v agar Hv-Cab medium with supplements as required. A toothpick was used to stab-inoculate the agar followed by incubation at 45°C upright in a plastic box with added wet paper towels to maintain humidity. Paper towels were changed daily. Motility assay plates were removed from the 45°C incubator after three days and imaged after one day of room temperature incubation as this increased the carotenoid production, allowing for better visibility of the halos. Motility halos were quantified using Fiji (ImageJ) (v. 2.9.0)⁴⁹. Images were uploaded to Fiji, and the scale was set based on plate diameter. Statistical significance of halo diameters was assessed with an unpaired t-test using GraphPad Prism v. 9.5.1 (528) for macOS (GraphPad Software, San Diego, California USA, www.graphpad.com).