Effect of cell wall modifications on exolytic activity of lactococcal phage endolysins and phage growth

Lactococcus lactis and Lactococcus cremoris are widely used as starters in the food industry but its activity may be compromised by bacteriophages, viruses that exclusively infect bacteria. Thus, a huge effort has been put to develop lactococcal phage-resistant strains. This dataset describes the results of experiments designed to test the hypothesis if a thwarted endolysin activity influences the outcome of phage infection. To this end, turbidity reduction assays were performed with Lys1358 and LysC2, endolysins with CHAP and lysozyme catalytic domains, respectively. Lactococcus mutants either overexpressing or lacking genes involved in the cell envelope stress (CES) response or in modifying peptidoglycan (PG) composition were used as substrate cells. Reduced activity on cells with an induced CES response was detected for both endolysins, while LysC2 showed increased activity against cells depleted of the PG deacetylase PgdA and the O-acetyl transferase OatA. By measuring several growth parameters of phage c2 on these mutants (lytic score, efficiency of plaquing, plaque size and one-step curves), we could not stablish a direct link between a reduced or enhanced exolytic activity of endolysin and phage performance.