MCCLATCHY, J. K. (The University of Texas Southwestern Medical School, Dallas), AND E. D. ROSENBLUM. Genetic recombination between a-toxin mutants of Staphylococcus aureus. J. Bacteriol. 92:580-583. 1966.-A demonstration of genetic recombination between Staphylococcus aureus nonhemolytic mutants was attempted by means of transduction. The results of two-point reciprocal transductions placed the mutants into two genetic groups. Recombination within each group was not detectable within the limits

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... of the method, but hemolytic recombinants were obtained in transductional crosses when donor and recipient were from different groups. At least two genetic loci are therefore involved in a-toxin production. The 11 mutants of group II were fibrinolysin-negative. The recombinants were always found to be restored to fibrinolysin production as well as to a-toxin production. These data suggest the existence of a pleiotropic gene simultaneously affecting the synthesis of both a toxin and fibrinolysin. The nine mutants of group I were fibrinolysin-positive. Group I members are postulated to be a-toxin structural mutants. Three mutants were also negative for bound coagulase, but no linkage was observed between the locus controlling bound coagulase and the loci for either fibrinolysin or a-toxin production.