Isolation and lytic activity of the Listeria bacteriophage endolysin LysZ5 against Listeria monocytogenes in soya milk

• Published in: Food microbiology Vol. 31; no. 1; pp. 133 - 136
• Main Authors: Zhang, Hui, Bao, Hongduo, Billington, Craig, Hudson, J. Andrew, Wang, Ran
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.08.2012; Elsevier
• Subjects: Anti-Infective Agents - metabolism; Bacteriophages - enzymology; Bacteriophages - genetics; Biocontrol; Biological and medical sciences; Biological Control Agents; Cloning, Molecular; DNA, Viral - genetics; Endolysin; Endopeptidases - metabolism; Enterococcus faecalis - metabolism; Escherichia coli - genetics; Escherichia coli - metabolism; Food Contamination - analysis; Food Handling - methods; Food industries; Food Microbiology; Food Preservation - methods; Fundamental and applied biological sciences. Psychology; Genes, Viral; Listeria monocytogenes - isolation & purification; Listeria monocytogenes - virology; Listeria phage; Milk and cheese industries. Ice creams; N-Acetylmuramoyl-L-alanine Amidase - genetics; N-Acetylmuramoyl-L-alanine Amidase - metabolism; Refrigeration; Sequence Analysis, DNA; Soy Milk; Staphylococcus aureus - metabolism; Endolysin; Listeria phage; Biocontrol; Virus; Biological control; Dairy product; Listeria monocytogenes; Bacteria; Isolation; Phage; Milk
• ISSN: 0740-0020; 1095-9998
• DOI: 10.1016/j.fm.2012.01.005

The endolysin gene (lysZ5) from the genome of the Listeria monocytogenes phage FWLLm3 was cloned in Escherichia coli and characterized. Comparative sequence analysis revealed that lysZ5 resembled the murein hydrolase ply511 encoded by L. monocytogenes phage A511. The encoded protein LysZ5 had a predicted molecular mass of 35.8 kDa and was expressed in E. coli as an N-terminal fusion protein of 41.5 kDa. Addition of purified fusion protein to lawns of indicator bacteria showed that LysZ5 could lyse L. monocytogenes, Listeria innocua and Listeria welshimeri, but not Staphylococcus aureus or Enterococcus faecalis. The purified protein was able to kill L. monocytogenes growing in soya milk, with the pathogen concentration reduced by more than 4 log10 CFU ml−1 after 3 h incubation at 4 °C. As far as we know, this is the first report of a Listeria phage endolysin to control pathogens in soya milk and to demonstrate endolysin activity in foods at refrigeration temperatures. Moreover, LysZ5 may also be useful for biocontrol in other ready-to-eat foods. ► A newly identified phage endolysin rapidly lysed Listeria monocytogenes in broth at 25 °C. ► The endolysin was active against L. monocytogenes in soya milk and control was achieved under refrigeration. ► This is the first report of a cloned phage endolysin active at temperatures used for the chilled storage of foods.