Staphylococcus aureus is a Gram positive pathogenic bacterium of man and his domestic animals which lends iself reasonably well to routine genetic analysis and laboratory manipulations. At the present time it is one of the very few pathogenic bacteria which is being studied at the genetic level. It thus not only is an important pathogen in its own right, but is a "model" of many other Gram positive pathogens. The primary goal of this proposed research is to characterize this bacterium in terms of the genetic organization of its chromosome, and to recognize those attributes associated with pathogenicity which may be determined by extrachromosomal genetic determinants. Presently, we have analyzed 7 "chromosomal" markers by transformation, and have shown that 6 of these 7 markers exist in either 1 of 2 linkage groups. Additional markers are being sought, allowing a genomic map to be developed. Within this map, it should be possible to at least provide the framework for determining the genetic location of genes responsible for virulence (coagulase production, hemolytic activity, DNase production, etc). As time permits the fine structure genetic details of several of the biosynthetic pathways will also be examined.