Coagulin, a bacteriocin-like inhibitory substance produced by Bacillus coagulans I sub(4)

A protease-sensitive antibacterial substance produced by Bacillus coagulans I sub(4) 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 degree C for 90 min, at a pH ranging from 4 to 8 and appeared to be unaffected by alpha -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 I sub(4) strain harbours a plasmid, pI sub(4), 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 pI sub(4), whereas the second harboured a deleted form of this plasmid, thus suggesting a plasmid location for the genes for coagulin production.