Environmental Stress Induces Altered Composition of Streptococcus mutans Membrane Vesicles: pH-Driven Changes in Membrane Vesicle Production and Composition.

Bacteria produce membrane vesicles (MVs) in response to environmental stress and genetic changes. Previous studies have shown that MVs can trigger inflammatory responses and may serve as important mediators of host-microbe interactions. Given the dynamic nature of the oral microbiome, bacteria such as Streptococcus mutans are frequently exposed to environmental fluctuations that could alter MV production. The objective of this study was to investigate whether inducing stress conditions would affect MV production and morphology in S. mutans, a prominent oral pathogen. Cultures were subjected to different pH conditions to mimic environmentally relevant stress. MVs were isolated and purified in order to characterize and assess changes in yield, size, and cargo. Our findings show that acidic stress significantly increased MV production while reducing average MV size. We also observed significant differences in MV content when compared to control conditions. These changes may reflect bacterial adaptation strategies and could influence how MVs interact with host immune systems. Overall, this study highlights the potential for environmental stress to reshape MV-mediated communication in the oral microbiome and provides a foundation for exploring how such changes may contribute to inflammation and oral disease.