Cotransduction of two or even three plasmids was -observed when a Staphylococcus aureus strain, carrying five distinct, compatible plasmids, was used as donor. An active host recombination system did not seem to be indispensable for plasmid cotransduction, since RecA+ and RecAdonors gave similar cotransduction frequencies. Analysis of plasmids carried by cotransductant clones demonstrated that a genetic interaction can take place between cotransduced plasmids, leading to new plasmids. Some of

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... e properties of these new plasmids are discussed. Another set of experiments tested the ability of a cotransducible plasmid to allow a significant degree ofmultiplication of a temperature-sensitive plasmid at restrictive temperature. In an attempt to explain the results obtained, a working hypothesis suggesting a transient and reversible association of cotransducible plasmids is presented. on May 9, 2020 by guest http://jb.asm.org/ Downloaded from mid.