CHARACTERIZATION OF A TOXIN-DEFICIENT CLOSTRIDIUM-PERFRINGENS STRAIN,KZ1340

Clostridium perfringens KZ1340, previously classified as Clostridium p lagarum, is an isolate from Antarctic soil, and was identified as an a lpha-, theta-, and kappa-toxin non-producing variant. On Southern hybr idization, the variant was found to be defective in the pfoA (theta-to xin) gene, but the pie (alpha-toxin) and colA (kappa-toxin) genes were present on the same EcoRI fragment as in the standard strain, NCTC823 7. Northern analysis revealed that mature pie mRNA was transcribed in KZ1340 though less efficiently than in NCTC8237, while no mature colA mRNA was present in KZ1340, After transformation of the pfoA and pie g enes into the KZ1340 via shuttle vector, pJIR418, the pfoA gene was su ccessfully expressed but the pie gene was not efficiently expressed, s uggesting that in KZ1340 there is negative regulation of plc gene expr ession, Toxin-deficient C. perfringens KZ1340 might be a suitable host for expression analysis of the pfoA gene and other clostridial virule nce genes, if expressed efficiently, because it produces a small amoun t of extracellular toxins.