Gut virome derived bacteriophage endolysin Lys572 can effectively control Streptococcus suis in refrigerated and thawed pork.

Abstract

Streptococcus suis (S. suis), a major zoonotic pathogen in pork production, contaminates meat products and processing facilities, posing risks to both animal and human health. Virome analysis enables the identification of novel antibacterial protein genes directly from environmental genetic material without microbial cultivation, offering a promising approach for discovering bacteriophage endolysins with applications in food safety and biopreservation. In this study, we identified a novel endolysin from porcine intestinal virome, named Lys572. Lys572 is a modular enzyme consisting of an N-terminal CHAP domain, a central Amidase-2 domain, and a C-terminal ZoocinA_TRD domain. Cys30, His95, Glu112 and Glu276 were identified as key sites for maintaining the activity of the catalytic domain. The lytic activity of Lys572 remained stable at temperatures ranging from -80 to 45 °C, pH values from 3.0 to 10.0, and was not significantly affected by varying NaCl concentrations. In vitro, Lys572 exhibited highly effective antibacterial activity against both S. suis and Streptococcus equi. In addition, Lys572 can effectively remove mature biofilms of S. suis. Importantly, Lys572 can effectively reduce the number of S. suis in refrigerated and thawed pork. During storage at 4 °C for 48 h, 50 μg/mL of Lys572 can effectively reduce S. suis in pork by approximately 2 log CFU/mL. Lys572 also effectively reduced bacterial loads during thawing at 4 °C and 30 °C, with a maximum reduction of 2.0-2.2 log CFU/mL. These results indicate that Lys572 is a promising antibacterial candidate for controlling S. suis contamination in pork products.