Interspecific Transformation in Hemophilus; A Possible Index of Relationship Between H. Influenzae and H. aegyptius.

Abstract

When aliquots of the same recipient population of Hemophilus influenzae or Hemophilus aegyptius are exposed simultaneously to desoxyribonucleic acids (DNA) derived from streptomycin (SM)-re-sistant cells of the same strain or from different H. influenzae and H. aegyptius strains, the proportions of cells in which SM-resistance is induced are of the same order of magnitude. The results obtained are comparable to those found in intraspecific transformation. On the other hand, the proportion of cells of either H. influenzae or H. aegyptius transformed to SM-resistant by the DNA from Hemophilus parainfluenzae is in the range expected in interspecific transformation. On the premise that the degree of reactivity of donor DNA with the heredity determinants of the recipient cell is a reflection of the degree of homology of the genome of donor and recipient cells, it has been proposed that transformation may serve as a valid criterion for bacterial taxonomy. If the use of a single genetic marker, SM-resistance, provides a valid basis for comparison, H. aegyptius may be a member of the H. influenzae group.