What form of genetic transfer involves direct contact between bacteria?

Conjugation is the form of genetic transfer that involves direct contact between bacteria. This process typically requires a physical connection between donor and recipient cells, often facilitated by a structure known as a pilus. During conjugation, one bacterium transfers genetic material—usually in the form of plasmid DNA—directly into another bacterium, allowing for the sharing of traits such as antibiotic resistance or metabolic capabilities.

In contrast, transduction involves the transfer of genetic material via bacteriophages (viruses that infect bacteria) and does not require direct cell-to-cell contact. Transformation refers to the uptake of free DNA from the environment by a competent bacterium, which also does not involve direct contact with another bacterial cell. Horizontal transfer is a broader term that encompasses various methods of genetic exchange among organisms but does not specifically denote direct contact. Thus, conjugation is the most accurate term for this type of genetic transfer.