CLONING OF A DNA-SEQUENCE UNIQUE TO CLOSTRIDIUM-BOTULINUM GROUP-I BY SELECTIVE HYBRIDIZATION

Nucleic acid sequences were isolated from a strain of Clostridium botu linum type A by a selective hybridization method known as deletion enr ichment. Nontoxigenic C sporogenes was used to produce a C. botulinum type A sequence-enriched library. A probe, pCBM44, which showed specif ic hybridization to a 4.0-kb HindIII fragment present in all of the C. botulinum type A strains tested was isolated, and there was no hybrid ization to any strains of C. sporogenes. Upon further investigation, p CBM44 was found to hybridize to all of the group I proteolytic C. botu linum strains tested (toxin types A, B, and F) but not to hybridize to groups II, III, and IV (toxin types B, C, D, or E). The probe did not cross-react with nine other Clostridium spp. Such a probe, which diff erentiates between nontoxigenic C. sporogenes and neurotoxigenic C. bo tulinum group I strains, should prove extremely useful.