The resistance to nisin was examined for the vegetative forms and the endospores of 14 strains of 9 species of the genus Bacillus. Bacilli, endospores and culture filtrates were tested for ability to inactivate nisin. Marked antinisin activity was detected in extracts of bacilli and endospores of organisms which have a lytic mechanism for rupture of the spore coat (type L); little or no activit...