Which term refers to the mixing of genetic material between two microorganisms?

The term that refers to the mixing of genetic material between two microorganisms is conjugation. During conjugation, two bacteria come together and establish a connection known as a pilus, allowing for the transfer of genetic material, often in the form of plasmids. This process is a form of horizontal gene transfer, enabling the recipient organism to acquire new traits, such as antibiotic resistance or metabolic capabilities.

While transformation also involves genetic exchange, it specifically refers to the uptake of free DNA from the environment by a bacterial cell, rather than direct transfer between two living organisms. Transduction is a process where bacteriophages, or viruses that infect bacteria, facilitate the transfer of genetic material between bacteria, which is distinct from the direct mixing that occurs in conjugation. Recombination generally involves the integration of genetic material into an organism's genome but does not specifically denote the mechanism through which the genetic material is obtained. Hence, conjugation is the most accurate term describing the direct mixing of genetic material between two microorganisms.