Enterococcus faecalis hemolysin-bacteriocin plasmids belong to the same incompatibility group

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Plasmids are crucial genetic elements in bacteria, influencing traits like antibiotic resistance and virulence.
• Understanding plasmid interactions, such as coexistence and incompatibility, is vital for bacterial genetics and evolution.
• Enterococcus faecalis harbors various plasmids, including those encoding hemolysin-bacteriocin (Hly-Bcn) functions.

Purpose of the Study:

• To investigate the coexistence patterns among nine Enterococcus faecalis hemolysin-bacteriocin (Hly-Bcn) plasmids.
• To determine the compatibility of the Hly-Bcn plasmid pIP964 with five R plasmids.
• To identify and designate a new plasmid incompatibility (Inc) group.

Main Methods:

• Plasmid coexistence assays were performed using Enterococcus faecalis strains harboring different Hly-Bcn and R plasmids.
• Displacement percentages were quantified to assess plasmid compatibility.
• Entry exclusion was monitored to understand the mechanisms of incompatibility.

Main Results:

• The nine Hly-Bcn plasmids exhibited significant incompatibility with each other, with displacement rates ranging from 40% to 100%.
• One Hly-Bcn plasmid, pIP964, demonstrated stable coexistence with all five tested R plasmids.
• Incompatibility among the Hly-Bcn plasmids was frequently associated with entry exclusion.

Conclusions:

• The nine studied Hly-Bcn plasmids constitute a distinct incompatibility group, designated IncHly.
• Plasmid pIP964 represents a unique case of stable coexistence with R plasmids within E. faecalis.
• The IncHly group exhibits characteristic incompatibility and entry exclusion mechanisms.