Staphylococcus aureus transcriptomic response to inhibition by H2O2-producing Lactococcus garvieae

Area of Science:

• Food Microbiology
• Bacteriology
• Molecular Biology

Background:

• The dairy strain Lactococcus garvieae N201 produces hydrogen peroxide, inhibiting the growth of the foodborne pathogen Staphylococcus aureus in milk and cheese.
• Understanding the molecular mechanisms of this inhibition is crucial for food safety.

Purpose of the Study:

• To investigate the transcriptomic responses of two Staphylococcus aureus strains (dairy SA15 and human pathogenic MW2) to inhibition by L. garvieae N201.
• To determine the influence of aeration levels (high and low) on the interaction and gene expression.

Main Methods:

• Comparative transcriptomics of S. aureus SA15 and MW2 exposed to L. garvieae N201 in Brain-Heart Infusion broth.
• Analysis under both high and low aeration conditions.
• Assessment of S. aureus survival and gene expression related to stress response, cell division, and virulence.

Main Results:

• S. aureus MW2 exhibited higher resistance to L. garvieae inhibition and hydrogen peroxide under high aeration.
• Both strains showed similar inhibition under low aeration.
• L. garvieae generally repressed S. aureus genes involved in stress response and cell division.
• Differential gene expression, particularly of virulence factors, was observed between S. aureus strains and influenced by aeration levels.

Conclusions:

• Aeration significantly modulates Staphylococcus aureus resistance and virulence gene expression during inhibition by Lactococcus garvieae.
• Hydrogen peroxide production by L. garvieae is a key factor in S. aureus inhibition.
• This study provides insights into the molecular basis of bacteriocin-mediated pathogen control by Lactic Acid Bacteria.