Conditionally essential genes for survival during starvation in Enterococcus faecium E745.

Area of Science:

• Microbiology
• Environmental Microbiology
• Bacterial Pathogenesis

Background:

• Enterococcus faecium is a nosocomial pathogen known for prolonged survival on surfaces without nutrients.
• This survival ability is linked to its spread within hospital environments.
• Mechanisms underlying nutrient-independent survival in E. faecium remain poorly understood.

Purpose of the Study:

• To identify genes essential for the long-term survival of Enterococcus faecium in nutrient-limited conditions.
• To elucidate the molecular mechanisms behind the environmental robustness of E. faecium.

Main Methods:

• High-throughput transposon sequencing (Tn-seq) was employed to screen a mutant library.
• Mutants were incubated in phosphate-buffered saline (PBS) at 20°C to simulate nutrient-deprived conditions.
• Targeted gene deletion and complementation were used to validate gene functions.

Main Results:

• Tn-seq identified 24 genes contributing to survival in PBS, involved in stress response, DNA repair, metabolism, and membrane homeostasis.
• The universal stress protein (usp) gene (EfmE745_02439) was quantitatively most important for PBS survival.
• Deletion of usp significantly impaired survival, which was restored by complementation, confirming its critical role.

Conclusions:

• The universal stress protein (usp) is postulated as a key determinant of E. faecium's environmental robustness.
• Further research into usp and other identified genes will illuminate survival mechanisms in nutrient-deprived states.
• Understanding these mechanisms can inform strategies to control E. faecium in healthcare settings.