Horizontal gene transfer

Horizontal gene transfer (HGL), also called Lateral gene transfer (LGT), is the process of transfering genetic material between different species, or across broad taxonomic categories.

Main mechanisms of gene transfer in prokaryotes

HGT between distant microbial phyla is mediated by bacteriophages, plasmids, transposons, and specialized DNA uptake mechanisms. These mechanisms usually categorized with the following:

• Bacterial transformation , the genetic alteration of a cell resulting from the introduction, uptake and expression of foreign genetic material, generally DNA (see this animation with audio explanation). This process is relatively common in certain naturally transformable bacteria, such as the soil bacterium Bacillus subtilis. Transformation is often used as a biotechnology to insert novel genes into bacteria for scientific research experiments, or for industrial or medical applications.
• Transduction, the process in which bacterial DNA is moved from one bacterium to another by a bacterial virus (a bacteriophage, commonly called a phage).
• Bacterial conjugation ( or mating), a process in which a living bacterial cell transfers genetic material through direct cell-to-cell contact (see the animation conjugation in Escherichia coli).

The risks of horizontal gene transfer

1. Antibiotic resistance genes spreading to pathogenic bacteria.
2. Disease-associated genes spreading and recombining to create new viruses and bacteria that cause diseases.
3. Transgenic DNA inserting into human cells, triggering cancer.