Non-targeted analysis using liquid chromatograph-hybrid mass spectrometer reveals growth substrates of Pseudomonas aeruginosa in tap water.

Pathogenic bacteria can proliferate in disinfectant-depleted tap water when they utilize organic matter as growth substrates. Although the concentration of assimilable organic carbon has been used to estimate substrate quantities in tap water, the full qualitative composition remains largely uncharacterized. In this study, we used a liquid chromatograph-hybrid mass spectrometer for non-targeted analysis of dissolved organic matter to screen for potential growth substrates for Pseudomonas aeruginosa in drinking water. From 4247 components in tap water, 81 substrate candidates were screened. Three dicarboxylic acids-suberic acid, azelaic acid, and sebacic acid-were identified by MS/MS analysis and co-chromatography. Quantum chemical calculations were used to explore the fragmentation pathways of the suberic acid anion in MS/MS, and the results supported the validity of the observed product ion spectra. These dicarboxylic acids, which have not been previously listed in metabolic databases, were identified as substrates capable of acting as sole carbon sources for P. aeruginosa. This study demonstrates a new approach for discovering previously unrecognized organic substrates utilized by specific microorganisms in environmental samples.