Characterization and antibacterial activity of highly thermo- and pH-stable endolysin LysCPQ7 and its application as a biocontrol agent against Clostridium perfringens in milk and cheese

Phage-encoded peptidoglycanases (phage endolysins) are hydrolyzing enzymes that break peptidoglycan bonds within infected bacterial cell walls at the end of the lytic cycle. They are promising antibacterial agents capable of controlling major foodborne pathogens. Here, we cloned, overexpressed, and purified the phage-encoded protein LysCPQ7, a putative endolysin from the Clostridium perfringens phage CPQ7. The predicted amino acid sequence indicated that LysCPQ7 exhibited amidase activity to digest the peptidoglycan bond between muramic acid and peptide in bacterial cell walls. LysCPQ7 was characterized as an alkalophilic and thermostable endolysin. It exhibited the highest lytic activity against C. perfringens cells at pH values ranging from 9.0 to 11.0, and was stable at temperatures from −20 to 60 °C. The lytic activity of LysCPQ7 was not significantly (p