Bacteriophage and Anti-phage Mechanisms in Lactic Acid Bacteria

Bacteriophages are the principal cause of starter culture failure in many food fermentations carried out by lactic acid bacteria (LAB). The understanding and correct exploitation of phage resistance mechanisms are vital for the development of robust LAB starter cultures that can withstand phage infection and consistently produce desirable products. Plasmid-encoded mechanisms can be particularly functional if the plasmid can be mobilized to other strains via food-grade methods. Chromosomally encoded phage resistance mechanisms can be categorized as phage adsorption inhibition, inhibition of phage deoxyribonucleic acid injection, restriction/modification, abortive infection, and the clustered regularly interspaced short palindromic repeat-Cas system. The increased availability of dairy streptococcal phage genome sequences has permitted the development of a multiplex polymerase chain reaction system that encompasses all known phage groups for the bacterial species. Lactobacillus is a highly diverse bacterial genus with in excess of 200 species recognized.