GENETIC RECOMBINATION OF STREPTOMYCIN RESISTANCE IN ESCHERICHIA COLI STRAIN K-12

Abstract

The genetic difference between streptomycin-"indifference", the high and full resistance developed in a single step, and streptomycin-"resistance" in a narrow sense, the resistance developed by multiple steps, has been shown by recombination techniques using Escherichia coli strain-12. When "indifferent" cells were crossed with sensitive cells, the progeny showed ether sensitiveness or "indifference", no progeny being found at all which had intermediate degrees of resistance. On the other hand, when "resistant" cells were crossed with sensitive cells, the progeny showed various degrees of intermediate resistance which the parent resistant cells used to have in the course of acquiring their final resistances. These results seem to indicate the single gene origin of streptomycin "indifference" and the polygenic origin of streptomycin-"resistance."