writersoul- I didn’t mention restriction endonucleases. Those are enzymes that bacteria use as a primitive immune system to distinguish self from non-self DNA. Basically, those endonuclease enzymes cut DNA sequences that are foreign to that organism. It is analogous to human (or most Eukaryotic complex organisms) that use major histocompatibility complexes to display peptides on their cell surfaces to “notify” the humoral (NK cells) and adaptive (T-cells, many different subtypes) immune cells of foreign proteins being produced.
When it comes to bacteria, prokaryotes don’t “mate.” They can horizontally transmit genetic material through processes known as conjugation or transformation, but the only way they reproduce is through binary fission.