Probing Interkingdom Signaling Molecules via Liquid Extraction Surface Analysis–Mass Spectrometry

Shaun N. Robertson, Fadi Soukarieh, Thomas M. White, Miguel Camara, Manuel Romero*, and Rian L. Griffiths*


Previously, metabolites diffused or secreted from microbial samples have been analyzed via liquid chromatography–mass spectrometry (LC–MS) approaches following lengthy extraction protocols. Here, we present a model system for growing biofilms on discs before utilizing rapid and direct surface sampling MS, namely, liquid extraction surface analysis, to study the microbial exometabolome. One of the benefits of this approach is its surface-specific nature, enabling mimicking biofilm formation in a way that the study of planktonic liquid cultures cannot imitate. Even though Pseudomonas aeruginosa (P. aeruginosa), Staphylococcus aureus (S. aureus), and Candida albicans (C. albicans) have been studied previously in isolation, very few studies consider the complexity of the interplay between these pathogens, which are commonly combined causative agents of infection. Our model system provides a route to investigate changes in the exometabolome, such as metabolites that become circulatory in the presence of multiple pathogens. Our results agree with previous reports showing that 2-alkyl-4(1H)-quinolone signal molecules produced by P. aeruginosa are important markers of infection and suggest that methods for monitoring levels of 2-heptyl-4-hydroxyquinoline and 2,4-dihydroxyquinoline, as well as pyocyanin, could be beneficial in the determination of causative agents in interkingdom infection including P. aeruginosa. Furthermore, studying changes in exometabolome metabolites between pqs quorum sensing antagonists in treated and nontreated samples suggests suppression of phenazine production by P. aeruginosa. Hence, our model provides a rapid analytical approach to gaining a mechanistic understanding of bacterial signaling.

Advion Interchim Scientific® TriVersa NanoMate® (Advion Interchim Scientific®, Ithaca, NY) was utilized for the LESA sampling.

Development of an Automated High-Throughput Platform for Shotgun Lipidomics

Xianlin Han, Kui Yang and Richard W. Gross

Lipidomics, defined as the large-scale study of the pathways and networks of cellular lipids in biological systems, is an emerging and rapidly expanding research field. Although lipidomics has only emerged as a distinct field within the past few years, numerous new discoveries and advances have already been made. Among them, multi- dimensional mass spectrometry (MS)-based shotgun lipidomics has distinguished itself as a robust and highly informative analytical platform for MS analyses of individual lipid molecular species directly from biological lipid extracts. The current platform for shotgun lipidomics includes a series of simple steps such as multiplexed extractions/reactions during sample preparation, intrasource separation/selective ionization, identification of individual lipid molecular species using building block-based multi-dimensional MS (MDMS), and quantitation of the identified individual lipid molecular species using a two-step ratiometric method.

Advion Interchim Scientific® TriVersa NanoMate® was featured in this publication.