TRANSFORMATION OF HAEMOPHILUS-INFLUENZAE FOLLOWING ELECTROPORATION WITH PLASMID AND CHROMOSOMAL DNA

Naturally transformable species, such as Haemophilus influenzae, have evolved systems for the efficient uptake and integration of DNA from the surrounding environment. We compared this competence-dependent DNA uptake system to electroporation, which has been widely used in the past few years to introduce DNA into cells, for transforming Haemophilus influenzae. Electroporation improved transformation efficiency when noncompetent cells were used and when DNA lacking Haemophilus-specific uptake sequences was used for transformation of competent cells. An increase in plasmid-to-chromosome recombination was seen when plasmid DNA containing chromosomal inserts was introduced into competent cells by electroporation, as observed previously for natural transformation.