Plasmids encoding bacteriophage resistance for use in lactic acid bacteria

There are disclosed plasmids which encode bacteriophage resistance including host controlled restriction/modification and abortive infection activity. These plasmids may be introduced into lactic acid bacteria employed in the food industry which bacteria are sensitive to bacteriophage so as to generate resistant variants. Moreover, plasmids can be generated comprising at least two nucleotide sequences encoding phage defence mechanisms selected from the group consisting of host controlled restriction, host controlled modification, abortive infection and prevention of phage absorption.