Gregory, Kenneth F. (Ontario Agricultural College, Guelph, Ontario, Canada), and Jay C. C. Huang. Tyrosinase inheritance in Streptomyces scabies. I. Genetic recombination. J. Bacteriol. 87:1281–1286. 1964.—Mutants derived from Streptomyces scabies strain A26 recombined with other derivatives of A26, but not with nine other strains of S. scabies nor with eight strains of other streptomycetes. Most of the spore progeny of heterogenomic mycelia formed from complementary diauxotrophic strains of S. scabies A26 were capable of forming tyrosinase (tye+), provided either of the parents was tye+. About 99.8% of these spores carried the nutritional markers of either one or the other of the two parents. All recombinant classes between nutritional and streptomycin susceptibility markers were like-wise predominantly tye+. We suggest that the tye+ characteristic is carried in a small genetic unit, which is unlinked to most other genes and capable of replicating faster than the rest of the S. scabies genome.