Plasmids generally contain genes that confer a selective advantage to
their bacterial hosts through antibiotic resistance or virulence
factors. However, despite these advantages,plasmid transfer rates are
normaly very low due to segregation and fitness costs to their hosts;
too low to account for their widespread existence.
I would like to hear from anyone who has any insight into this matter.
There are some reported cases where evolved plasmids introduced into
bacteria have increased their fitness almost two-fold.
Any information would be much apreciated