TRANSDUCTIONAL HETEROGENOTES IN ESCHERICHIA COLI

Abstract

HE transduction of the Gal+ factor (ability to ferment galactose) to Gal-T mutants of Escherichia coli K12 has been described in a previous report The galactose positive transduction clones were often found to be unstable and to throw off Galtypes about once per thousand divisions. We postulated that the transformed cells were heterogenotic (heterozygous for the transduced fragment), and that the instability was a result of segregation. This process has been studied in more detail with several non-allelic Galmutants. Since transduction genetics is a system analogous but not identical with sexual crossing, which also occurs in these strains, a distinctive terminology is a useful tool for integrating hypothesis and experiment. The following definitions are given for reference a t this point. Their applications will be amplified in the experimental report.