BACTERIOPHAGE HOST INTERACTIONS AND RESISTANCE MECHANISMS, ANALYSIS OF THE CONJUGATIVE BACTERIOPHAGE RESISTANCE PLASMID PNP40

Research into bacteriophage and bacteriophage resistance in the lactic acid bacteria has moved into a new and exciting dimension in recent y ears. Mechanisms such as adsorption inhibition, restriction and modifi cation, and abortive infection which have been described phenotypicall y over the past decade are now being subjected to molecular analysis, and this has led to a better understanding of the nature and variety o f resistance systems employed by lactic acid bacteria to combat phage attack. in addition, analysis of different bacteriophage has increased our knowledge of these ubiquitous particles to the point where it is possible to construct novel phage resistances based on the phage genom e. This review will briefly outline the recent progress in the molecul ar analysis of bacteriophage-host interactions, bacteriophage resistan ce and counter resistance, and the construction of novel resistance me chanisms. In particular, recent evidence regarding the mechanisms of r esistance employed by the conjugative plasmid pNP40 will be described in some detail. In addition, an instance will be described in which pN P40 has been used in the construction of phage resistant starters whic h have been successfully exploited by the dairy industry.