β-Galactosidase assay
We generated non-polar deletions of lacZY genes from wild-type PA13 named PA13L and confirmed that all traits were identical in the two strains. Wild-type and mutant backgrounds used in the β-galactosidase assays were PA13L. All of the test strains were grown for 20 h and sub-cultured in LB broth at 28°C. The assays were performed with exponential-phase cultures at an OD600 of ~ 0.4 as described previously (Choi et al ., 2019).