Phenotypic Plasticity of Staphylococcus aureus in Liquid Medium Containing Vancomycin

Area of Science:

• Microbiology
• Genetics
• Evolutionary Biology

Background:

• Phenotypic plasticity allows organisms to adapt to environmental changes, promoting evolution.
• Genome-wide association studies (GWAS) are crucial for understanding the genetic underpinnings of bacterial traits.
• Investigating bacterial phenotypic plasticity, particularly in response to antibiotics, is vital for understanding adaptation and resistance.

Purpose of the Study:

• To explore the genetic basis of growth plasticity in Staphylococcus aureus exposed to vancomycin.
• To identify specific single-nucleotide polymorphisms (SNPs) associated with differential growth responses.
• To evaluate the utility of bivariate GWAS for studying bacterial phenotypic plasticity.

Main Methods:

• Cultured 41 Staphylococcus aureus strains, including 29 vancomycin-intermediate strains (VISA), with and without vancomycin for 48 hours.
• Analyzed growth curves and maximum growth rates to quantify plasticity.
• Conducted a bivariate GWAS to map SNPs associated with growth plasticity across 14 time points.

Main Results:

• Strains with identical vancomycin minimum inhibitory concentrations (MICs) exhibited varying degrees of growth plasticity.
• Identified 227 SNPs associated with growth plasticity, with 15 high-frequency SNPs mapped to annotated genes.
• Key genetic elements, including non-coding regions, ebh, drug transporters, and pepV, were implicated in vancomycin-induced growth plasticity.

Conclusions:

• Bivariate GWAS is a feasible and effective strategy for dissecting bacterial phenotypic plasticity.
• Specific genetic variations significantly influence Staphylococcus aureus' adaptive growth in the presence of vancomycin.
• This research provides insights into the adaptive strategies of S. aureus and informs future studies on antibiotic resistance.