Bacterial extracellular vesicles as recyclable nutrient reservoirs

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Bacterial extracellular vesicles (EVs) are recognized mediators of intercellular communication, virulence, and immune modulation.
• The role of bacterial EVs as nutrient reservoirs has not been previously explored.

Purpose of the Study:

• To investigate the potential of bacterial EVs as recyclable nutrient reservoirs.
• To elucidate the mechanisms and conditions governing EV degradation and nutrient release.

Main Methods:

• Utilized Bacillus cereus and Staphylococcus aureus as model organisms.
• Analyzed EV dynamics under varying growth conditions (nutrient-rich vs. nutrient-limited media).
• Employed time-resolved multi-omics profiling, pharmacological inhibition, knockout mutants, and enzymatic complementation.
• Conducted growth assays to assess the impact of EV degradation on bacterial growth.

Main Results:

• Bacterial EVs exhibit condition-dependent stability: degradation in nutrient-rich media, accumulation in nutrient-limited conditions.
• Sphingomyelin-containing EVs undergo degradation mediated by secreted sphingomyelinase (SMase).
• SMase-driven EV degradation releases biomolecular cargo, serving as a nutrient source.
• SMase activity provides a significant growth advantage to bacteria during nutrient depletion.

Conclusions:

• Bacterial EVs function as dynamic and recyclable nutrient reservoirs.
• Sphingomyelinase-mediated degradation of EVs is a key mechanism for nutrient acquisition.
• This process enhances bacterial survival and growth under nutrient-limiting conditions.