Characterization of Two <i>Salmonella</i> Myoviruses and a Novel Lysis-Inhibition System

Background: Salmonella infecting phages are one of the attractive alternatives to treat antibiotic-resistant infections. Here, we aimed to isolate Salmonella phages and study their lysis genes. Materials and Methods: The water samples were collected from the Texas A&amp;M University (TAMU) wastewater treatment plant, Texas and Salmonella Typhi LT2 was used as a host strain. Host range, life cycle, growth kinetics, and thermal stability were studied. The predicted lysis genes were subsequently evaluated with the λ complementation method. Results: Two Salmonella myoviruses, Manna and Mansal, belonging to Tequatrovirus and Kuttervirus genera, respectively, were isolated. The lysis genes of Manna are all closely related to the T4 counterparts. The Mansal gp21 was shown to be a class I holin by complementation tests. Conclusion: Mansal was found to exhibit canonical lysis inhibition (LIN) but has no homologs of the T4 LIN genes rI and rIII , thus representing the first experimentally confirmed LIN system among class I holins.