Infection and Immunology - Bacterial Conjugation

LECTURE:


I think of “conjugal visits” whenever I hear this term. And we all know what happens in a conjugal visit! Conjugation requires a male bacterium and a female bacterium; no viruses are involved here.

First, you need to know who the man is in this relationship. It's the bacterium that is F+, or positive for a Fertility factor. In other words, it is the bacterium capable of forming a sex pilus, which resembles a penis really.

This F+ man often has some really cool genes that he wants to pass on, and what better way to share the wealth than by conjugation.

Sometimes, the fertility factors is found in the one of the man's plasmids that happens to contain other genes, like resistance genes.

In other cases, the F genes are actually integrated into the chromosome, and these parts of the chromosome can be passed during conjugation. Remember that the chromosomal DNA is circular and that resistance gene needs to be "downstream" from the initiation sequence to be passed. Also, know that the closer the resistance gene is to the Fertility element in the circular DNA, the more likely it will be passed during sex.

Either way, conjugation is both an effective way to share the fertility factor and a good way to incidentally share resistance genes.