An IncN plasmid exhibiting a high frequency of transfer in broth media

A mutant of the IncN plasmid N3T was isolated. This mutant (pNJ101) exhibits equal transfer frequencies in broth and on agar. IncN plasmids have rigid pili and do generally transfer at much lower frequencies in broth than on agar, hypothetically explained as the vulnerability of the pili towards convection forces in liquid. Strains with the mutant do have rigid pili, so other mechanisms regulating IncN plasmid transfer must be sought.