Bacteriophage defence systems in lactic acid bacteria

The study of the interactions between lactic acid bacteria and their bacter iophages has been a vibrant and rewarding research activity for a considera ble number of years. In the more recent past, the application of molecular genetics for the analysis of phage-host relationships has contributed enorm ously to the unravelling of specific events which dictate insensitivity to bacteriophage infection and has revealed that while they are complex and in tricate in nature, they are also extremely effective. In addition, the stra tegy has laid solid foundations for the construction of phage resistant str ains for use in commercial applications and has provided a sound basis for continued investigations into existing, naturally-derived and novel, geneti cally-engineered defence systems. Of course, it has also become clear that phage particles are highly dynamic in their response to those defence syste ms which they do encounter and that they can readily adapt to them as a con sequence of their genetic flexibility and plasticity. This paper reviews th e exciting developments that have been described in the literature regardin g the study of phage-host interactions in lactic acid bacteria and the inno vative approaches that can be taken to exploit this basic information for c urtailing phage infection.