F-positive bacterium

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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):

See also: