Observing the invisible through imaging mass spectrometry, a window into the metabolic exchange patterns of microbes

Abstract

Many microbes can be cultured as single-species communities. Often, these colonies are controlled and maintained via the secretion of metabolites. Such metabolites have been an invaluable resource for the discovery of therapeutics (e.g. penicillin, taxol, rapamycin, epothilone). In this article, written for a special issue on imaging mass spectrometry, we show that MALDI-imaging mass spectrometry can be adapted to observe, in a spatial manner, the metabolic exchange patterns of a diverse array of microbes, including thermophilic and mesophilic fungi, cyanobacteria, marine and terrestrial actinobacteria, and pathogenic bacteria. Dependent on media conditions, on average and based on manual analysis, we observed 11.3 molecules associated with each microbial IMS experiment, which was split nearly 50:50 between secreted and colony-associated molecules. The spatial distributions of these metabolic exchange factors are related to the biological and ecological functions of the organisms. This work establishes that MALDI-based IMS can be used as a general tool to study a diverse array of microbes. Furthermore the article forwards the notion of the IMS platform as a window to discover previously unreported molecules by monitoring the metabolic exchange patterns of organisms when grown on agar substrates.

Phenol Soluble Modulin (PSM) Variants of Community-Associated Methicillin-Resistant Staphylococcus aureus (MRSA) Captured Using Mass Spectrometry-Based Molecular Networking

“…The invaluable tool of MS has played a major role in characterizing biosynthetic release factors for a diverse number of organisms (19). Over the past decade, the field has spawned several innovative methods to optimize data collection, processing, and organization.…”

MALDI Imaging Mass Spectrometry of Fresh Water Cyanobacteria: Spatial Distribution of Toxins and Other Metabolites

“…Note also that the ions of m/z 619.1 (Figure 10b), 1643.6 (Figure 10f) and 1971.5 (Figure 10g) are in greater abundance between colonies and, therefore, related to "cross talking". 14,15,22 The ion of m/z 638.5 (Figure 10c) is, however, in greater abundance only on the colonies of the N. harveyana PCC 7804. The ion of m/z 989.4 (Figure 10d) is detected in all the three colonies, whereas that of m/z 1276.3 (Figure 10e) is abundant except for the colonies of the M. aeruginosa PCC 7820.…”

“…MALDI-IMS combines the high sensitivity and selectivity of MS with 2D surface screening analysis, and its scope has been expanded to deliver spatial distributions of several biomolecules such as metabolites and lipids in different biological matrices. 13 This technique has also been applied for analysis of microbial natural products, 14 microbial interactions 15 and metabolic profiling of microorganisms. 16 Recently, MALDI-IMS has been tested for filamentous marine cyanobacteria, 17 showing the spatial distribution of natural products.…”

Mass Spectrometry Imaging of Biomolecular Information

“…It was shown that many of the imaged alkaloids form specific tissue associations within the complexity of the sponge matrix. A study on metabolic exchange patterns of microbes revealed the complexity of molecular communication of microbes including the secretion of parmaceutically interesting compounds such as antibiotics or cancer therapeutical drugs 222,223 . A number of other studies were reported in this context recently 15,[224][225][226][227] .…”