ISOLATION, PARTIAL CHARACTERIZATION, AND MODE OF ACTION OF ACIDOCIN J1132, A 2-COMPONENT BACTERIOCIN PRODUCED BY LACTOBACILLUS-ACIDOPHILUS JCM-132

Lactobacillus acidophilus JCM 1132 produces a heat-stable, two-compone nt bacteriocin designated acidocin J1132 that has a narrow inhibitory spectrum. Maximum production of acidocin J1132 in MRS broth was detect ed at pH 5.0. Acidocin J1132 was purified by ammonium sulfate precipit ation and sequential cation exchange and reversed-phase chromatographi es. Acidocin J1132 activity was associated with two components, termed alpha and beta. On the basis of N-terminal amino acid sequencing and the molecular masses of the alpha and beta components, it is interpret ed that the compounds differ by an additional glycine residue in the b eta component. Both alpha and beta had inhibitory activity, and an inc rease in activity by the complementary action of the two components wa s observed, Acidocin J1132 is bactericidal and dissipates the membrane potential and the pH gradient in sensitive cells, which affect such p roton motive force-dependent processes as amino acid transport. Acidoc in J1132 also caused efflux of preaccumulated amino acid taken up via a unidirectional ATP-driven transport system, Secondary structure pred iction revealed the presence of an amphiphilic alpha-helix region that could form hydrophilic pores. These results suggest that acidocin J11 32 is a pore-forming bacteriocin that creates cell membrane channels t hrough the ''barrel-stave'' mechanism.