Studies on phage nucleic acid relating to toxin production of Clostridium botulinum types C and D.

C型和D型肉毒梭菌的产毒性通过特定的噬菌体感染从产毒菌株转化为非产毒菌株。从5个转换噬菌体c-st、c-468、c-203、c-d6f、d-1873和1个非转换噬菌体c-N71中提取核酸，观察它们对核酸酶的敏感性。所有分离的核酸都不被RNase A消化，而是被DNase和核酸外切酶消化，表明它们是双链DNA。根据Hind&lt；III&gt；和Eco RI在0.8%琼脂糖凝胶上的限制性内切酶酶切图谱，c-st、c-N71、c-468和c-d6f噬菌体DNA的长度约为110kbp，c-203和d-1873的长度约为150kbp。所有噬菌体DNA均可被HPA<I>消化，但不能被Xho<I>消化。不同噬菌体对PST<I>和Sau3A的敏感性不同。C-st、c-N71和c-468的DNA对PST敏感，而对Sau3A不敏感。PST对c-st和c-N71噬菌体DNA的消化图谱完全相同，而对c-468噬菌体DNA的酶切图谱仅少了一条带。C-st和c-N71噬菌体的Hind&lt；III&gt；消化模式也非常相似。然而，在另一种噬菌体和核酸酶的情况下，除了c-203和c-d6f噬菌体的几条共同的条带，以及六个噬菌体DNA的共同的几条带外，并没有观察到如此良好的相似性。在与这些噬菌体DNA的斑点杂交试验中，证明了六个噬菌体DNA都存在几个共同的碱基序列(区域)。然而，大量的同源性只存在于c-st、c-N71和c-468 DNA之间。这些结果表明，c-st、c-N71和c-468的DNA相似，但不同于其他噬菌体的DNA，c-N71噬菌体转化能力的丧失可能不是由于“tox”基因的缺失，而是c-st噬菌体DNA的碱基突变所致。

Toxigenicity of Clostridium botulinum types C and D is converted from toxigenic to nontoxigenic strains by the infection with specific bacteriophages. The nucleic acids were extracted from five converting phages, c-st, c-468, c-203, c-d6f, d-1873, and one nonconverting phage, c-n71, and observed their susceptibility to nucleases. All of the nucleic acids isolated were not digested by RNase A, but digested by DNase <I> and exonuclease <III> , indicating that they were double stranded DNA. From the digestion patterns on 0.8% agarose gel electrophoresis by restriction endonucleases of Hind <III> and Eco RI, the length of c-st, c-n71, c-468, and c-d6f phage DNAs was estimated to be about 110 Kbp, and that of c-203 and d-1873 was about 150 Kbp. All of the phage DNAs were also digested by Hpa <I> , but not by Xho <I> . The susceptibility to Pst <I> and Sau 3A was different depending on the phages. The DNAs from c-st, c-n71, and c-468 were susceptible to Pst <I> , but not to Sau 3A. The digestion patterns of c-st and c-n71 phage DNAs by Pst <I> were exactely the same, and that of c-468 phage DNA was only one band less from them. The Hind <III> digestion patterns of c-st and c-n71 phages were also very similar. In another cases of phages and nucleases, however, such a good similarity was not observed though a few bands common to c-203 and c-d6f phages, and also several bands common to six phage DNAs were demonstrated. In dot hybridization test with these phage DNAs, the existence of several base sequences (regions) common to all of six phage DNAs was demonstrated. A large amount of homology, however, existed only between c-st, c-n71, and c-468 DNAs. These results indicate that DNAs of c-st, c-n71, and c-468 are similar to each other, but different from those of another phages, and that loss of converting ability of c-n71 phage may be caused not by the deletion of "tox" gene but the base mutation in c-st phage DNA.