Enterococcus lactis is ecologically and genetically distinct from the major opportunistic pathogen Enterococcus...

Area of Science:

• Microbiology
• Evolutionary Biology
• Genomics

Background:

• Enterococcus faecium is a significant opportunistic human pathogen.
• Enterococcus lactis is a closely related, commensal species that is understudied.
• The genetic relationship and evolutionary history between these two species are not well understood.

Purpose of the Study:

• To compare the genome content and evolutionary relationships of Enterococcus faecium and Enterococcus lactis.
• To investigate the host range and genetic variation within these two closely related species.
• To understand the ecological dynamics and evolutionary trajectories of commensal versus pathogenic enterococci.

Main Methods:

• Whole-genome sequencing of 894 Enterococcus faecium and 392 Enterococcus lactis isolates.
• Comparative pangenome analyses to assess genetic variation and recombination rates.
• Analysis of host species distribution across different clades.

Main Results:

• Enterococcus faecium exhibits a broader host range, with specialized clades found in domesticated and pet animals.
• Enterococcus lactis demonstrates significantly higher allelic variation and lower core gene recombination rates compared to E. faecium.
• These findings suggest E. lactis may have occupied its ecological niche for a longer duration.

Conclusions:

• Enterococcus lactis appears to be an older species with a more stable ecological niche compared to the adaptable pathogen Enterococcus faecium.
• Comparative genomic studies of closely related commensal and pathogenic bacteria are crucial for understanding evolutionary processes.
• This research provides insights into the divergence and evolutionary histories of enterococcal species.