Page "Plasmid" Paragraph 18

It is possible for plasmids of different types to coexist in a single cell.

Several different plasmids have been found in E. coli.

However, related plasmids are often incompatible, in the sense that only one of them survives in the cell line, due to the regulation of vital plasmid functions.

Thus, plasmids can be assigned into incompatibility groups.