Design and implementation of a strategy to reduce bacteriophage infection of dairy starter cultures

Bacteriophages can cause a significant economic loss for the dairy industry which uses lactic starter cultures to produce fermented dairy products including cheeses and yoghurt. Over the past 25 years, a number of different approaches have been explored and implemented to reduce the problems of bacteriophage infection in part through the development of bacteriophage resistant lactic acid starter culture strains. A strategy employing antisense RNA designed against essential bacteriophage replication functions has proven to be a unique system for engineering bacteriophage resistant Lactococcus lactic starter cultures. Resistance to a class of bacteriophages has been achieved, for example, by expression of an antisense RNA targeted against a conserved yet cryptic bacteriophage gene. This approach may prove useful for engineering a set of truly isogenic strains to be used in a starter culture rotation plan.