Profiling of VOCs released from different salivary bacteria treated with non-lethal concentrations of silver nitrate

Abstract

Considering the shortcomings related to antibiotics usage, the introduction of other bacteriostatic and bactericidal agents that present synergetic effects or standalone properties is urgently needed. AgNO3 is an important bactericidal agent, which imparts various functions on bacteria dependent on its concentration. Therefore, an understanding of its mechanisms of action in infinitesimal concentrations plays an important role which can ultimately lead to AgNO3 involvement in the pharmaceutical industry. The monitoring of VOC (volatile organic compound) profiles emitted by bacteria is a simple method to assess changes occurring in bacterial metabolism. In this study, VOCs of Hafnia alvei, Pseudomonas luteola and Staphylococcus warneri cultures were analyzed both in the absence and in the presence of three concentrations of AgNO3. Headspace solid-phase microextraction gas chromatography/mass spectrometry (HS-SPME-GC/MS) was employed for extraction and analysis. After supplementation with AgNO3, changes in the emitted fingerprints were investigated. Odorants associated with mouth-related and systemic diseases, like dimethyl trisulfide, indole (halitosis) and 2-hexanone (celiac disease), were also affected by addition of AgNO3. Statistical tests proved discrimination between obtained profiles with more that 90% variability. Moreover, physiological states of bacteria after dosage with various concentration of stressing agent were investigated and explained by the mechanisms of action.