PR001787 (Project)

Description:Progress in the ion mobility mass spectrometry (IM-MS) field has significantly increased our ability to make small molecule and lipid identifications, making it an attractive approach for untargeted multi-omics experiments. The dimensionality of collision cross section (CCS) coupled with tandem mass spectrometry (MS/MS) for feature annotation has become a useful tool for high confidence structural elucidation in complex mixtures in the absence of authentic standards. A comprehensive method for feature identification of small organisms has remained limited to exploring genetic markers and protein signatures, however these methods for identification only scratch the surface of effective methods for bacterial classification. Multi-omic methods that include the metabolome and lipidome have grown in popularity due to the increased capacity for organism specific information. We have achieved species-level identification of Enterococcus faecium, Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa using a modern single-phase extraction method with hydrophilic interaction liquid chromatography (HILIC) coupled to traveling wave ion mobility mass spectrometry (TWIMS). To test the robustness of this optimized workflow, we included internal standards as a metric for efficiency of the extraction, and well known calibrants for validation for our CCS calibration method. We observed significant differences in metabolite profiles at the strain level using multi-variate statistics, primarily including quorum sensing metabolites in Gram-negative strains, and energy production metabolites in the Gram-positive strains. Lipid profiles showed staggering differences in acyl tail compositions that effectively categorized the microbes, including several classes of phospholipids and glycolipids. We have demonstrated a powerful workflow using multi-dimensional techniques for bacterial speciation in a single injection.