The plasmid and bacterial recombination. The slender tube between the two bacteria of different strains in this electron micrograph is known as a "pilus." Its proteins are produced in a plasmid-plus bacterium by two genes on the plasmid chromosome. The pilus is a plasmid's way of moving its genes from bacterium to another. Once the pilus forms the plasmid undergoes a round of replication. The new plasmid chromosome passes through the pilus into the plasmid-minus bacterium. The arrival of a plasmid changes the recipient into a plasmid-plus bacterium, which is capable of repeating the process. Magnification = x40,000.