In an examination of 10 categories of infant foods obtained in the Washington, D.C. area, Clostridium botulinum spores were detected in 2 of 100 samples of honey and 8 of 40 samples of corn syrup. This is the first report of the occurrence of C. botulinum spores in retail samples of corn syrup. In an ensuing nationwide survey of corn syrup, C. botulinum spores were detected in 5 of 961 bottles examined.

The ability of unheated and heated spores of Clostridium botulinum types B. E, and F to grow and produce toxin in crabmeat from the blue crab at low temperatures was investigated. Sterilized crabmeat was seeded with 103 unheated spores/g or 104 heated spores/g and incubated anaerobically at 4, 8, 12, and 26 C. Broth cultures served as controls. Both unheated and heated spores of the three strains grew and produced toxin in crabmeat at 26 C in 3 and 6 days, respectively. In addition, unheated spores of the nonproteolytic type E strain grew and produced toxin in crabmeat at 12 C in 14 days. Neither heated spores of type E nor heated or unheated spores of types B and F grew in crabmeat at any refrigerated temperature within 180 days.

The ability of Clostridium botulinum types A and B spores to grow and produce toxin in shredded cabbage at room temperature under a modified atmosphere was investigated. Seven type A and seven type B strains of C. botulinum, mostly of vegetable origin, were used as inocula. Shredded cabbage in high barrier bags, 250 g/bag, was inoculated with various numbers of spores, sealed under a modified atmosphere of 70% CO2 and 30% N2 and incubated at room temperature. Duplicate bags were examined for organoleptic acceptability and the presence of toxin from day 3 by blending the entire contents of each bag and injecting mice with dilutions of the extracts. Toxic extracts were typed with appropriate antitoxins. Only type A spores grew and produced toxin in the cabbage. An inoculum of approximately 100–200 type A spores/g of cabbage, whether in single strains or in various combinations, produced toxin on days 4, 5, and 6, while the cabbage was still organoleptically acceptable, as determined by appearance, odor, and texture.

An enrichment medium containing trypticase, peptone, glucose, yeast extract, and 1 mg of trypsin/ml (TPGYT) has been developed for detection of Clostridium botulinum type E. It was designed to potentiate toxin as produced and destroy the boticins of competing type E variants in cultures of foods and environmental materials. Samples of 227 sediments and 283 shellfish from different areas of the continental United States yielded 74 more positive cultures of type E in TPGYT than in the same medium free of trypsin. Type E toxin was detected in all smoked fish inoculated with 4 to 100 type E spores per fish in TPGYT. Incorporation of trypsin into the medium caused no reduction in type A or proteolytic type B toxin production from spore inocula. Toxins of nonproteolytic types B and F in pure culture were fully potentiated in the trypsin-containing medium.

Relationships of the somatic antigens among Clostridium botulinum strains have been investigated by tube agglutination and agglutinin absorption tests. Results revealed a relationship by which strains of C. botulinum are grouped by their proteolytic capacity rather than by the type of specific toxin produced. Thus, C. botulinum type E and its nontoxigenic variants, which are nonproteolytic, share common somatic antigens with the nonproteolytic strains of types B and F. Absorption of antiserum of a strain of any one type with antigen of any of the others removes the antibody to all three types. In the same manner, C. botulinum type A shares somatic antigens with the proteolytic strains of types B and F, and absorption of any one antiserum with an antigen of either of the other two types removes the antibody to all three types. Partial cross-agglutination of C. sporogenes, C. tetani, and C. histolyticum with the somatic antisera of the proteolytic group was also observed.