KARS1 and infection: In the presence of phages, the optical density of the Tn mutants OG1RF_10820-Tn (lytR), cscK-Tn, and OG1RF_12241-Tn (lysR) was constant over time, whereas the growth of the wild type and the pipEF receptor mutant declined or increased over the course of infection, respectively (Fig. 2A and B).