Plasmid-related transmissibility and multiple drug resistance in Streptococcus faecalis subsp. zymogenes strain DS16

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Streptococcus faecalis subsp. zymogenes is a bacterium with potential pathogenic properties.
• Plasmids are extrachromosomal DNA elements that can carry genes conferring advantageous traits, such as antibiotic resistance or virulence factors.

Purpose of the Study:

• To characterize the plasmids present in Streptococcus faecalis subsp. zymogenes strain DS16.
• To determine the genetic determinants and transmissibility of these plasmids.

Main Methods:

• Plasmid DNA isolation and characterization.
• Conjugation experiments to assess transmissibility.
• Antibiotic resistance profiling.

Main Results:

• Two plasmids, pAD1 (35 megadaltons) and pAD2 (15 megadaltons), were identified.
• pAD1 is transmissible and encodes a hemolysin-bacteriocin.
• pAD2 is non-conjugative and confers resistance to erythromycin, streptomycin, and kanamycin.
• pAD2 can be mobilized by pAD1, often forming a pAD1-pAD2 cointegrate.

Conclusions:

• Streptococcus faecalis subsp. zymogenes strain DS16 harbors distinct plasmids with different functional roles.
• The interplay between pAD1 and pAD2 influences plasmid mobility and genetic exchange within the bacterial population.