Plasmid curing in bacteria

TLDR: The aims of this manuscript are to summarize and review plasmid curing agents and procedures in view of the importance of plasmids in specifying antibiotic and metal-resistance; metabolic properties; pathogenicity; host specificity and nodulation; conjugal properties, and replication-maintenance properties.

Abstract: Plasmids are extrachromosomal pieces of double-stranded circular DNA which have the capability to replicate independently of the host chromosome, yet coexist with it [1]. To date, many species of bacteria isolated from diverse habitats are known to contain plasmid DNA [2,3]. Some plasmids are stable and can be maintained through successive generations by being partioned to each daughter cell during cell division. This allows each cell to receive at least one plasmid copy. In recent years, plasmids have been observed in a wide variety of bacteria. In part, this is due to the development of new procedures that allow the detection, isolation, and molecular characterization of plasmid DNA. When working with some plasmid-containing bacteria, it is often desirable to obtain a plasmid-cured derivative. This allows a direct comparison to be made between the plasmid-containing and plasmid-cured cells. Some plasmids undergo spontaneous segregation and deletion. However, the majority are extremely stable, and require the use of curing agents or other procedures (elevated growth temperature, thymine starvation), to increase the frequency of spontaneous segregation [4]. The usefulness of curing agents is unpredictable in many bacterial strains, as there are no standard protocols applicable to all plasmids. However, there are some procedures that have provided good results with certain species. The aims of this manuscript are to summarize and review plasmid curing agents and procedures. In view of the importance of plasmids in specifying antibiotic and metal-resistance; metabolic properties; pathogenicity; host specificity and nodulation ( Rhizobium spp.); conjugal properties, and replication-maintenance properties [2], reproducible procedures for obtaining plasmid-cured derivatives are necessary.