# Surface-Enhanced Raman Spectroscopy for Adenine Detection in Five Selected Bacterial Strains Under Stress Conditions

## TL;DR

This study shows that adenine, a stress marker, can be detected in bacteria using a cost-effective Raman spectroscopy method with gold and silver nanoparticles.

## Contribution

The study introduces a stable, cost-effective SERS method for detecting bacterial stress through adenine metabolite analysis.

## Key findings

- Adenine was detected as a stress marker in five bacterial strains under osmotic stress.
- Stable gold and silver nanoparticles enabled label-free SERS detection of secreted metabolites.
- Adenine signals originated from bacterial metabolites in the environment, not the cell wall.

## Abstract

What are the main findings?

Adenine was detected as a stress marker in five bacterial strains.Stable Au and Ag NPs enabled SERS-based analysis of secreted bacterial metabolites.

Adenine was detected as a stress marker in five bacterial strains.

Stable Au and Ag NPs enabled SERS-based analysis of secreted bacterial metabolites.

What is the implication of the main findings?

Label-free SERS detects metabolic stress responses in bacteria cost-effectively.Gold NPs enable long-term, reproducible Raman-based bacterial stress detection.

Label-free SERS detects metabolic stress responses in bacteria cost-effectively.

Gold NPs enable long-term, reproducible Raman-based bacterial stress detection.

This pilot study investigated the metabolic responses of five selected bacteria to physiological stress. Surface-enhanced Raman spectroscopy was used to analyze spectral changes associated with the release of adenine, a key metabolite indicative of stress conditions. Laboratory-synthesized spherical silver and gold nanoparticles, which remained stable over an extended period, were employed as enhanced surfaces. Bacterial cultures were analyzed under standard conditions and in the presence of a selected stressor—demineralized water—inducing osmotic stress. The results showed that the adenine signal originated from metabolites released into the surrounding environment rather than directly from the bacterial cell wall. The study confirms the suitability of these cost-effective and easily synthesized stable nanoparticles for the qualitative detection of bacterial metabolites using a commercially available Raman instrument.