Metabiotic effect of Bacillus licheniformis on Clostridium botulinum: implications for home-canned tomatoes

The metabiotic effect of Bacillus licheniformis on Clostridium botulinum was examined. B. licheniformis elevated the pH of a model system with an initial pH of 4.4 so that C. botulinum grew and produced toxin. Toxin production was observed when spores from both species were coinoculated at levels as low as 10 spores per ml. When pint jars of tomatoes were used, canner size contributed to a 10,000-fold difference in the lethality of a boiling water bath process on B. licheniformis spores. Botulinal toxin was not detected in pH-elevated jars of tomatoes containing C. botulinum spores.