biostudies-literatureRendueles CMinisterio de Ciencia, Innovación y Universidades2508https://www.ebi.ac.uk/biostudies/studies/S-EPMC11942015biostudies-literatureUnknown26(6)Bacteriophages (or phages) remain the leading cause of failure in dairy fermentations. Thereby, phage-resistant <i>Lactococcus lactis</i> and <i>Lactococcus cremoris</i> dairy starters are in continuous demand. In this work, our goal was to identify phage defense mechanisms against ceduoviruses encoded by two wild isolates of dairy origin named <i>L. lactis</i> IPLA517 and IPLA1064. These strains were previously subjected to experimental evolution to select derivatives that are resistant to the bacteriocin Lcn972. It was observed that the Lcn972^R derivatives became sensitive to phage infection; however, the underlying mechanism was not defined. The long-read sequencing technologies applied in this work reveal that all of the Lcn972^R derivatives shared the loss of a 41International journal of molecular sciencesA Plasmid-Encoded Surface Polysaccharide Partly Blocks &lt;i&gt;Ceduovirus&lt;/i&gt; Infection in Lactococci.PMC11942015PID2020-119697RB-I00Ruiz-Maso JABarra JLGaray-Novillo JNRendueles CMartinez BRau MHGaspar PMahony JRodriguez ADel Solar GfalseA Plasmid-Encoded Surface Polysaccharide Partly Blocks &lt;i&gt;Ceduovirus&lt;/i&gt; Infection in Lactococci.Bacteriophages (or phages) remain the leading cause of failure in dairy fermentations. Thereby, phage-resistant <i>Lactococcus lactis</i> and <i>Lactococcus cremoris</i> dairy starters are in continuous demand. In this work, our goal was to identify phage defense mechanisms against ceduoviruses encoded by two wild isolates of dairy origin named <i>L. lactis</i> IPLA517 and IPLA1064. These strains were previously subjected to experimental evolution to select derivatives that are resistant to the bacteriocin Lcn972. It was observed that the Lcn972^R derivatives became sensitive to phage infection; however, the underlying mechanism was not defined. The long-read sequencing technologies applied in this work reveal that all of the Lcn972^R derivatives shared the loss of a 412025-01-01T00:00:00Z2025 Mar2026-04-08T18:26:12.234Z2025-06-25T03:04:24.609ZS-EPMC119420154014115010.3390/ijms26062508