With valentines day looming there is no better time than to discuss bacterial sex. More frequently referred to as Horizontal Gene Transfer (HGT), this process describes the way that bacteria can pass genetic information between one another to produce sometimes more adapted bacterial genomes for the particular environment. While we humans must wait for reproduction to create a new combination of genes, bacteria treat their DNA somewhat like tradable baseball cards, picking up new fragments from other bacteria in the environment. This HGT can lead to astonishingly fast rates of evolution in bacteria and is, in part, the reason that bacteria can rapidly become antibiotic resistant – if they happen to pick up a resistant gene from another bacteria, they can become resistant also.
HGT can occur through three primary mechanisms:
- TRANSFORMATION: Bacteria can take up fragments of ‘naked’ DNA that are just floating around in the environment, discarded from their original bacteria, or left behind when they die.
- TRANSDUCTION: DNA can be inserted into a bacteria by a virus – bacteriophage.
- CONJUGATION: When bacteria touch one another, a protrusion (called a sexual pilus) can extend between the cells, through which genetic material can be exchanged.