Specificity in deoxyribonucleic acid uptake by transformable Haemophilus influenzae

Abstract

Cells of H. influenzae strain Rd competent for genetic transformation irreversibly bound approximately five molecular fragments of H. influenzae DNA per cell; under identical conditions, DNA derived from E. coli B was not taken up (<1 molecule per 50 cells). Similarly, DNA from Xenopus laevis was not taken up by competent H. influenzae. Of the heterologous DNAs tested, only DNA from H. parainfluenzae interfered with the uptake of H. influenzae DNA, as judged by competition experiments employing either DNA binding or genetic transformation as the test system. The extracellular heterologous DNA did not suffer either single or double strand breakage upon exposure to competent H. influenzae.