Analysis of volatile metabolites from cultured bacteria by gas chromatography/atmospheric pressure chemical ionization–mass spectrometry

An analytical system using gas chromatography/atmospheric pressure chemical ionization-mass spectrometry (GC/APCI-MS) was suitably set up for the analysis of volatile metabolites from cultured bacteria. The developed system was proved to have high sensitivity: the detection limit for a standard sample of indole was 17 pg (33 ppt (parts per trillion) for 100 mL gas sample). The system was extensively applied to rapid analysis of volatile metabolites from different bacteria: Escherichia coli, Streptococcus pneumoniae, and two strains of Staphylococcus aureus. A total of 156 metabolite peaks were peculiar to one of the species among 163 metabolite peaks found for all of the bacteria. The experimental results suggest that the GC/APCI-MS has the potential to distinguish bacterial pathogens rapidly by detecting bacterial volatile metabolites.