Antimicrobial behavior of phage endolysin PlyPlOO and its synergy with nisin to control Listeria monocytogenes in Queso Fresco

摘要

Hispanic-style fresh cheeses, such as Queso Fresco (QF), have been linked to numerous listeriosis outbreaks in the United States. In this work, we have studied the antilisterial behavior and effectiveness of theListeriaphage endolysin PlyP100 in QF, as well as the potential synergy between PlyP100 and nisin. PlyP100 showed similar bacterial reduction regardless of varyingL. monocytogenesinoculum size in QF, and when the inoculation size was 1 Log CFU/g, no pathogen recovery after cheese enrichment was observed. PlyP100 was stable in QF for up to 28 days of cold storage exhibiting similar antilisterial activity regardless of when contamination withL. monocytogenesoccurred. PlyP100 alone exhibited a strong listeriostatic effect in QF, on the contrary, nisin alone was not effective to control the pathogen in QF during cold storage. The combination of nisin and PlyP100 showed a strong synergy in QF with non-enumerable levels ofL. monocytogenesafter 4 weeks of refrigerated storage. Moreover,L. monocytogenesisolates from cheeses treated with nisin, PlyP100, and their combination did not develop resistance to nisin or PlyP100. Our results support the use of PlyP100 combined with nisin as an efficientL. monocytogenescontrol measure in QF.