noun, plural: F+ bacteria
A bacterium with F factor existing as a plasmid and not integrated in the bacterial genome.
The F in F factor stands for fertility and the presence of F factor as a plasmid is the distinctive feature of F+ bacteria. During conjugation, F+ bacterium transfers a copy of F factor DNA with F– bacterium, making the latter capable of producing a sex pilus and thereby also making it capable of conjugation with other bacteria.
Compare (with other groups of bacteria in terms of F factor):