Genomic Diversity, Competition, and Toxin Production by Group I and II Strains Used in Food Challenge Studies.

Botulinum neurotoxins (BoNTs) produced by the bacteria are the causative agent of human and animal botulism, a rare but serious and potentially deadly intoxication. Foodborne botulism is caused by the consumption of foods containing BoNTs, which results from contamination of foods with spores and toxin production by the bacteria during growth within the food. Validation of the safety of food products is essential in preventing foodborne botulism, however, limited guidance and standards exist for the selection of strains used in food challenge studies. Sequencing and genomics studies have revealed that is a large, diverse, and polyphyletic species, with physiologic and growth characteristics studied only in a few representatives. Little is known about potential growth competition or effects on toxin production between strains. In this study, we investigated an applied cocktail of ten strains, seven Group I and three Group II. Whole genome SNP alignments revealed that this strain cocktail encompasses the major clades of the Group I and II species. While growth competition appears to exist between several of the strains, the cocktail as a whole resulted in high levels of BoNT production.