Inability to Detect Spores of Clostridium botulinum in Fish Protein Concentrates (FPC)

Samples of fish protein concentrates from a total of 124 production lots prepared in pilot plants by three different methods have been tested for the presence of viable Clostridium botulinum spores by incubating them in cooked meat medium and assaying the culture supernatant fluids for toxin. No spores of C. botulinum could be demonstrated with certainty in any of the 124 samples of FPC tested. Two of the supernatant fluids were lethal to mice, but their lethal effects appeared to be caused by factors other than C. botulinum toxin.