Q.What is transformation? Who discovered it, and in which organism?

Although bacteria multiply mainly through simple asexual cell division, they can also exchange genetic material between two cells in ways that produce genetic recombination, broadly comparable to sexual reproduction in other organisms. Three distinct mechanisms achieve this in bacteria: conjugation, transformation and transduction.

Conjugation is direct cell-to-cell contact, in which a donor bacterial cell forms a sex pilus that draws it against a recipient cell, and DNA (often carried on a plasmid) passes across this connection from donor to recipient. It was discovered by Joshua Lederberg and Edward Tatum in 1946 in the bacterium Escherichia coli.

Transformation is the direct uptake, by a recipient cell, of free ('naked') DNA fragments present in its surroundings, which it then incorporates into its own genome. It was discovered by Frederick Griffith in 1928 in his experiments with Streptococcus pneumoniae. …