Resumen de Coagulin, a bacteriocin-like inhibitory substance produced by Bacillus coagulans I4

M. C. Urdaci, C. Le Marrec B. Hyronimus * †

• A protease‐sensitive antibacterial substance produced by Bacillus coagulans I4 strain, isolated from cattle faeces, was classified as a bacteriocin‐like inhibitory substance and named coagulin. The inhibitory spectrum included B. coagulans and unrelated bacteria such as Enterococcus, Leuconostoc, Oenococcus, Listeria and Pediococcus. Coagulin was stable at 60 °C for 90 min, at a pH ranging from 4 to 8 and appeared to be unaffected by α‐amylase, lipase or organic solvents (10% v/v). Coagulin exhibited a bactericidal and a bacteriolytic mode of action against indicator cells. The apparent molecular mass was estimated to be about 3–4 kDa by SDS‐PAGE. The B. coagulans I4 strain harbours a plasmid, pI4, approximately 14 kb in size. Novobiocin curing experiments yielded two derivatives that no longer produced the bacteriocin‐like inhibitory substance. Plasmid content of these two derivatives showed that one had lost pI4,whereas the second harboured a deleted form of this plasmid, thus suggesting a plasmid location for the genes for coagulin production.