INDUCIBLE RESISTANCE AGAINST NISIN IN LACTOBACILLUS-CASEI

Most strains of Lactobacillus casei tested were found to be nisin-resi stant. The addition of nisin to a growing culture of a resistant strai n stopped growth for several hours; however, growth then resumed at th e previous rate. Nisin induced a resistance mechanism that was lost by one passage in nisin-free medium. During induction with nisin, the ce lls produced an anionic, phosphate containing polysaccharide with the subunits rhamnose and galactose. This polysaccharide protected sensiti ve cells of L. casei against the bactericidal action of nisin.