A Novel Bacteriophage Exclusion (BREX) System Encoded by the pglX Gene in Lactobacillus casei Zhang

Lactobacillus casei Zhang is a probiotic that confers beneficial effects on the host, and it is thus increasingly used in the dairy industry. The possession of an effective bacterial immune system that can defend against invasion of phages and exogenous DNA is a desirable feature for industrial bacterial strains. The bacteriophage exclusion (BREX) system is a recently described phage resistance system in prokaryotes. This work confirmed the function of the BREX system in L. casei and that the methyltransferase ( pglX ) is an indispensable part of the system. Overall, our study characterizes a BREX system component gene in lactic acid bacteria.