Plasmid transfer into members of the family Legionellaceae

Area of Science:

• Microbiology
• Bacterial genetics
• Horizontal gene transfer

Background:

• Plasmids are crucial for bacterial adaptation and evolution.
• Understanding plasmid transfer mechanisms in clinically relevant bacteria like Legionella is important.

Purpose of the Study:

• To investigate the conjugal transfer of plasmids RP4 and pPH1JI::Mu::Tn5 into Legionella and Tatlockia species.
• To assess the stability and transferability of these plasmids in new hosts.

Main Methods:

• Conjugal transfer experiments were performed using Escherichia coli as the donor and Legionella pneumophila, Fluoribacter bozemanae, and Tatlockia micdadei as recipients.
• Transconjugants were selected and maintained under nonselective conditions.
• Further transfer experiments were conducted from transconjugant strains to other Legionella/Tatlockia strains and a restriction-modification deficient E. coli strain.

Main Results:

• Plasmids RP4 and pPH1JI::Mu::Tn5 were successfully transferred to L. pneumophila and F. bozemanae with moderate frequency, and to T. micdadei with lower frequency.
• The introduced plasmids were stably maintained in transconjugant strains for at least 10 passages without selection.
• Subsequent transfer of these plasmids from Legionella/Tatlockia hosts to other strains of the same genera was largely unsuccessful, while transfer to a restriction-modification deficient E. coli strain occurred with moderate frequency.

Conclusions:

• Legionellae and Tatlockia species are capable of receiving plasmids from E. coli, but exhibit limited ability to act as donors.
• The poor intergeneric transfer suggests potential repression of transfer genes or inherent limitations in recipient capabilities within Legionella and Tatlockia.
• Restriction-modification systems in recipient bacteria may play a role in limiting plasmid uptake and establishment.