Characterization of a novel endolysin LysSA11 and its utility as a potent biocontrol agent against Staphylococcus aureus on food and utensils.

Here we show that the LysSA11 endolysin, derived from the virulent Staphylococcus aureus phage SA11, has lytic activity against staphylococcal strains. Bioinformatics analysis revealed an enzymatically active CHAP (cysteine, histidine-dependent amidohydrolases/peptidases) domain at the N-terminus of LysSA11 that showed amidase activity. A novel cell wall binding domain (CBD) in the C-terminus could bind to a broad spectrum of staphylococcal cells. The bactericidal activity of LysSA11 was determined in food and utensils artificially contaminated with methicillin-resistant S. aureus (MRSA). The amounts of MRSA bacteria in milk and on ham were significantly reduced by 1.44-log CFU/mL and 3.12-log CFU/cm(3), respectively, within 15 min at refrigeration temperature (4 °C) and by 2.02-log CFU/mL and 3.37-log CFU/cm(2), respectively, within 15 min at room temperature (25 °C). Moreover, a polypropylene plastic cutting board and a stainless steel knife artificially contaminated with approximately 4-log CFU/cm(2) of MRSA also showed complete bacterial elimination after a 30-min treatment with 1.35 μM of LysSA11. The data presented here strongly suggest that the novel CBD-containing staphylococcal endolysin LysSA11 can be used both as a food antimicrobial and as a practical sanitizer for utensils.