Studies of the various Gram-negative coccobacilli have revealed that for most genera, some, if not all, strains are competent for transformation. Another approach to the application of genetic transformation to bacterial classification makes use of a nutritional, or auxotrophic, mutant of a competent strain of the organism of interest. Practical transformation assays making use of the principles described above have been devised for identification of strains of Acinetobacter calcoaceticus, Moraxella osloensis, and Moraxella urethralis. All transformation assays work best when started with an overnight culture of the particular auxotrophic tester strain grown on a Heart Infusion plate at 34 to 36°C. The method described for the use of genetic transformation to identify unknown bacteria is, in principle, applicable to members of any genus for which there is at least one strain that is competent for genetic transformation. A transformation assay for identification of strains of Neisseria gonorrhoeae similar to the assays has been devised.