What is horizontal gene transfer and why is it significant in oral biofilms?

What is horizontal gene transfer and why is it significant in oral biofilms?

• A. It is the vertical transmission of DNA during cell division; it is not significant in biofilms.
• B. It is the transfer of genetic material between bacteria via transformation, conjugation, or transduction; it drives spread of resistance and virulence traits.
• C. It is random mutation during growth; it does not spread resistance.
• D. It is the exchange of plasmids only in lab conditions.

Answer: (B)

Horizontal gene transfer is the movement of genetic material between bacteria, not from parent to offspring. It happens through transformation (taking up free DNA from the environment), conjugation (direct transfer of DNA between cells, often via a pilus), and transduction (phage-mediated transfer). In oral biofilms, these processes are especially important because bacteria live in dense, mixed communities with lots of cell-to-cell contact and abundant extracellular DNA in the matrix. This environment makes gene exchange frequent, allowing resistance genes and virulence factors to spread among oral bacteria. As a result, biofilms can acquire new resistance traits and enhanced pathogenic capabilities, influencing treatment outcomes and the overall ecology of dental plaque. Vertical inheritance during cell division, not horizontal transfer, accounts for passing genes to offspring; random mutation changes within a lineage do not involve intercellular DNA transfer; and plasmid exchange is not confined to laboratory settings—it occurs in natural biofilms as well.

Horizontal gene transfer is the movement of genetic material between bacteria, not from parent to offspring. It happens through transformation (taking up free DNA from the environment), conjugation (direct transfer of DNA between cells, often via a pilus), and transduction (phage-mediated transfer). In oral biofilms, these processes are especially important because bacteria live in dense, mixed communities with lots of cell-to-cell contact and abundant extracellular DNA in the matrix. This environment makes gene exchange frequent, allowing resistance genes and virulence factors to spread among oral bacteria. As a result, biofilms can acquire new resistance traits and enhanced pathogenic capabilities, influencing treatment outcomes and the overall ecology of dental plaque. Vertical inheritance during cell division, not horizontal transfer, accounts for passing genes to offspring; random mutation changes within a lineage do not involve intercellular DNA transfer; and plasmid exchange is not confined to laboratory settings—it occurs in natural biofilms as well.