title: Isolation and lytic activity of the Listeria bacteriophage endolysin LysZ5 against Listeria monocytogenes in soya milk.
abstract: 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.
authors.affiliation: Key Lab of Agro-Food Safety and Quality Monitoring of Agriculture, Key Lab of Animal-derived Food Safety of Jiangsu Province, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.forename: Hongduo
authors.initials: H
authors.lastname: Bao
authors.forename: Craig
authors.initials: C
authors.lastname: Billington
authors.forename: J Andrew
authors.initials: JA
authors.lastname: Hudson
authors.forename: Ran
authors.initials: R
authors.lastname: Wang
mesh_terms: D000890:Anti-Infective Agents / Q000378:metabolism; D001435:Bacteriophages / Q000201:enzymology* / Q000235:genetics; D061046:Biological Control Agents; D003001:Cloning, Molecular; D004279:DNA, Viral / Q000235:genetics; D010450:Endopeptidases / Q000378:metabolism*; D013293:Enterococcus faecalis / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005506:Food Contamination / Q000032:analysis*; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods; D005814:Genes, Viral; D008089:Listeria monocytogenes / Q000302:isolation & purification / Q000821:virology*; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000235:genetics / Q000378:metabolism; D012034:Refrigeration; D017422:Sequence Analysis, DNA; D041942:Soy Milk; D013211:Staphylococcus aureus / Q000378:metabolism
chemical_list: D000890:Anti-Infective Agents; D061046:Biological Control Agents; D004279:DNA, Viral; D010450:Endopeptidases; C001143:endolysin; D009238:N-Acetylmuramoyl-L-alanine Amidase