Effect of subtilin and nisin on the spores of Bacillus coagulans.

The early literature on the effect of the polypeptide antibiotics subtilin and nisin on bacterial spores has been reviewed by Campbell and O'Brien (1955). Most of the early reports have indicated that subtilin acts as a sporostatic agent. Other reports have shown, however, that the spores of several bacterial species will germinate in the presence of subtilin and are subsequently killed by the antibiotic (Andersen, 1952; Michener, 1953, 1955; Sacks, 1955). This appears to be the main mode of action of subtilin on bacterial spores, although Sacks (1955) presented convincing evidence that subtilin was sporostatic for a small fraction of the spores of Bacillus macerans. Wheaton et al. (1957) found that subtilin was effective in preventing spoilage of tomato juice by Bacillus coagulans, although from their data they could not determine whether the antibiotic was sporocidal or sporostatic. Hirsch and Grinsted (1954), working with species of the genus Clostridium, reported that nisin could act, depending upon the test organism, either sporocidally or as an inhibitor of germination. Subtilin and nisin have also been reported to reduce the thermal resistance of spores of a number of bacteria important in the spoilage of heat processed foods (LeBlanc et al., 1953; Lewis et al., 1954; O'Brien et al., 1956) with the greatest reduction occurring with nisin and the spores of B. coagulans (O'Brien et al., 1956). This reduction in thermal resistance is probably more apparent