Combination of endolysins and high pressure to inactivate Listeria monocytogenes

• Published in: Food microbiology 2017-12, Vol.68, p.81-88
• Main Authors: van Nassau, Tomas J., Lenz, Christian A., Scherzinger, Anna S., Vogel, Rudi F.
• Format: Article
• Language: English
• Subjects: Bacteriophage lysin; Cell wall hydrolase; Cheese - microbiology; Endopeptidases - pharmacology; Enzymes; Fast Foods - microbiology; Food Preservation - methods; Gram-positive; Hydrostatic Pressure; Listeria monocytogenes - chemistry; Listeria monocytogenes - drug effects; Listeria monocytogenes - growth & development; Listeria monocytogenes - isolation & purification; Microbial Viability - drug effects; Peptidoglycan; Synergy
• ISSN: 0740-0020; 1095-9998
• DOI: 10.1016/j.fm.2017.06.005

Outbreaks of listeriosis are often related to the consumption of low-processed ready-to-eat food products (e.g. soft cheeses or smoked fish) contaminated with Listeria monocytogenes. Traditional preservation techniques, such as heat treatment, cannot eliminate Listeria from these products without strongly affecting the quality of the foods. We therefore investigated the use of endolysin (PlyP40, Ply511, or PlyP825) in combination with high hydrostatic pressure processing to kill L. monocytogenes in buffer. The results demonstrated a more than additive effect when both treatments were combined. For example, whereas 0.16 μg/mL PlyP825 or 300 MPa (1 min, 30 °C) applied individually reduced the cell count by 0.2 and 0.3 log cfu, respectively, a combined treatment resulted in a reduction of 5.5 log cfu. Similar results were obtained for the other endolysins combined with high pressure processing. We also showed that the synergistic inactivation of cells by endolysin and HHP is possible at a pressure level of only 200 MPa (2 min, 30 °C). Thus, the application of endolysins did not only substantially increase the bactericidal effect of high pressure, but it also enabled the inactivation of bacterial cells at much lower pressure levels. This shows the potential of using such combined processes for the inactivation of L. monocytogenes and food preservation. •Synergy between endolysins and HHP for the inactivation of L. monocytogenes.•Endolysin enables the inactivation of Listeria cells at much lower pressure levels.•Endolysin opens new possibilities for HHP preservation of pressure-sensitive foods.