[Extrachromosomal genetic elements of Clostridium botulinum. II. Isolation and analysis of DNA from bacteriophages of Clostridium botulinum types C and A].

The DNAs of bacteriophage c-st, known to realize the lysogenic conversion of toxinogenicity among C. botulinum types C and D strains, and the nucleic acid of a virulent mutant of bacteriophage CB propagated in type A C. botulinum cells were purified and examined. Heterogeneity of phage c-st preparations was observed during purification, manifesting by formation of several bands in isopiknic CsCl gradient during centrifuging. An extra nucleic acid fraction was detected in some DNA preparations of phage c-st; the origin of this fraction is discussed. Plasmid extrachromosomal elements were for the first time found in the cells of nontoxigenic type C C. botulinum A02 strain, known as the indicator for c-st phage. The sensitivity of phage c-st DNA to 25 restriction endonucleases was examined. Analysis of the results of restriction analysis of c-st and CB phage DNAs and plasmid nucleic acids, revealed earlier in type A C. botulinum strains, disclosed several DNA modification enzymes with different recognition sites in type C C. botulinum. At least two of these activities are not found in type A strains. According to restriction analysis, total size of phage c-st DNA is about 160 kbp and of phage CB DNA 35 kbp. Individual EcoRI and HindIII restricts of phage c-st DNA, containing the initial site of botulinum toxin CI gene, were recognized by radioisotope labeled oligonucleotide probe Enzyme immunoassay revealed slight expression of the N-terminal region of bntc I gene in E. coli recombinant variants. These data can be used in further investigation of C. botulinum genetics.