Bacterial metabolic remodeling by convergent evolution unlocks nutrient availability after a host switch.

Area of Science:

• Microbiology
• Evolutionary Biology
• Pathogen Adaptation

Background:

• Staphylococcus aureus is a significant human pathogen and a cause of bovine intramammary infection.
• Pathogen emergence often involves host jump events and subsequent adaptation.
• Understanding pathogen adaptation is crucial for controlling infectious diseases.

Purpose of the Study:

• To investigate the adaptive metabolic changes in Staphylococcus aureus following its switch to the bovine host.
• To identify the specific mechanisms enabling S. aureus to thrive in the dairy cattle niche.

Main Methods:

• Comparative genomic analysis of human and bovine S. aureus strains.
• Phenotypic characterization of casein degradation capabilities.
• Identification of genetic mutations associated with protease overexpression.

Main Results:

• Bovine S. aureus strains have evolved the ability to degrade casein, a major milk protein.
• This caseinolytic activity is mediated by the protease aureolysin, which is overexpressed due to mutations in distinct genetic loci.
• Convergent evolution of this trait occurred across different S. aureus lineages.

Conclusions:

• Staphylococcus aureus exhibits remarkable evolutionary plasticity, adapting its metabolism to utilize host-specific nutrients.
• The evolution of casein degradation is a key adaptation facilitating S. aureus proliferation in dairy cattle.
• This study elucidates a critical host-adaptive trait enabling pathogen success in a new environment.