Time-resolved metabolic fingerprinting of bacterial stress responses using surface-enhanced Raman spectroscopy.

Rapid and accurate detection of bacterial physiological states, including viability and stress responses, is essential for both microbiology research and clinical diagnostics. Conventional culture-based methods are slow, while molecular approaches often fail to capture dynamic metabolic responses. In this study, we present a proof-of-concept strategy that employs surface-enhanced Raman scattering (SERS) to monitor metabolites released by Staphylococcus aureus and Escherichia coli subjected to controlled-stress induced by transfer to deionized water. Our results demonstrate that bacterial stress responses may be monitored by changes in purine metabolism, indicated by SERS detection of adenine and hypoxanthine at concentrations far below the detection limits of conventional Raman spectroscopy. The long-term monitoring of metabolite excretion highlights the robustness of this approach for assessing bacterial stress dynamics. Taken together, these findings establish the feasibility of near-real-time metabolic fingerprinting of bacterial activity, offering a pathway toward rapid viability assessment and laying the foundation for future studies of bacterial responses to antimicrobial agents.