COAGULIN, A BACTERIOCIN-LIKE INHIBITORY SUBSTANCE PRODUCED BY BACILLUS-COAGULANS I-4

A protease-sensitive antibacterial substance produced by Bacillus coag ulans I-4 strain, isolated from cattle faeces, was classified as a bac teriocin-like inhibitory substance and named coagulin. The inhibitory spectrum included B. coagulans and unrelated bacteria such as Enteroco ccus, Leuconostoc, Oenococcus, Listeria and Pediococcus. Coagulin was stable at 60 degrees C for 90 min, at a pH ranging from 4 to 8 and app eared to be unaffected by alpha-amylase, lipase or organic solvents (1 0% v/v). Coagulin exhibited a bactericidal and a bacteriolytic mode of action against indicator cells. The apparent molecular mass was estim ated to be about 3-4 kDa by SDS-PAGE. The B. coagulans I-4 Strain harb ours a plasmid, pI(4), approximately 14 kb in size. Novobiocin curing experiments yielded two derivatives that no longer produced the bacter iocin-like inhibitory substance. Plasmid content of these two derivati ves showed that one had lost pI(4),whereas the second harboured a dele ted form of this plasmid, thus suggesting a plasmid location for the g enes for coagulin production.