Mechanisms of Toxin Production of Food Bacteria (Clostridium botulinum)

摘要

Clostridium botulinum types C and D produced at least three toxins designated as C1, C2, and D. When different strains of types C and D were cured of their prophages, they ceased to produce C1 and D toxins, respectively. Toxin production depended upon the continual participation of specific bacteriophages. Production of C2 toxin by these same strains, however, was not affected by these bacteriophages. Certain strains of types C and D could be interconverted to either type C or type D by specific bacteriophages. One phage-sensitive strain of C. botulinum type C became a common host to phages of types C and D and also Clostridium novyi type A. When this culture was infected with these phages, it produced C1 toxin or D toxin or C. novyi toxin, respectively. Further studies showed that bacteriophages governed the production of alpha toxin of C. novyi types A and B. Nontoxigenic derivatives have been isolated from C. botulinum types B (nonproteolytic), but they are not phage-sensitive. Toxigenic Clostridium botulinum and nontoxigenic C. sporogenes, C. subterminale, and C. botulinum-like organisms from a variety of sources have been screened for plasmids. Fifty percent of the 68 C. botulinum isolates carried one or more plasmids ranging in mass from 2.1 to 80 Mdal. A total of 63 plasmids were detected from both nontoxigenic and toxigenic strains.