Identification of a prophage-encoded abortive infection system in levilactobacillus brevis

Abortive infection systems (Abi) are phage resistance systems that can be prophage-encoded. Here, two genes encoding an Abi system were identified on a prophage sequence contained by the chromosome of the Levilactobacillus brevis strain UCCLBBS124. This Abi system is similar to the two-component AbiL system encoded by Lactococcus lactis biovar. diacetylactis LD10-1. The UCCLBBS124 prophage-derived Abi system (designated here as AbiL124) was shown to exhibit specific activity against phages infecting L. brevis and L. lactis strains. Expression of the AbiL124 system was shown to cause reduction in the efficiency of plaquing and cell lysis delay for phages of both species.