bacterial conjugation
/ bak-TEER-ee-ul kon-juh-GAY-shun /
When animals or plants reproduce, they shuffle genes between parents through sex. Bacteria do not have sex and do not need a partner to reproduce — they just copy themselves and split. But they have a separate trick for sharing useful genes directly with a neighbor, sometimes called bacterial 'mating.' That trick is conjugation, and it works more like passing a USB drive than like having children.
In conjugation, one bacterium (the donor) reaches out a thin tube-like appendage, often a pilus, and connects to a second bacterium (the recipient). Through this bridge it passes a copy of a small loop of DNA called a plasmid — a separate little ring of genes apart from the main chromosome. The recipient keeps the copy, gaining whatever the plasmid carries, while the donor keeps its own. No new cell is made and no offspring is born; this is gene sharing between two living cells, not reproduction.
Conjugation matters enormously in medicine because the genes that get shared are often the very ones that make bacteria dangerous, especially antibiotic-resistance genes. A single resistant cell can hand its resistance plasmid to neighbors — even to bacteria of a different species — turning a treatable population into an untreatable one. It is one of the main highways of horizontal gene transfer, the way traits spread sideways through the bacterial world rather than just down from parent to offspring.
In a hospital, a harmless gut bacterium carrying a resistance plasmid can conjugate with a disease-causing species sharing the same intestine, handing over resistance to several antibiotics at once. The dangerous bug never had to 'earn' that resistance — it was simply gifted.
Conjugation can hand resistance to a dangerous bacterium in a single contact.
Conjugation is gene transfer, not reproduction: the two cells exchange or copy DNA but do not make a new cell. Bacterial reproduction is the separate process of binary fission.