The Department of Chemistry Presents, via Webinar: Christopher Anderton, Pacific Northwest National Laboratory
Environmental microbiomes represent a complex mixture of interacting species with diverse physiologies and phylogenetic origins, and their functional outcomes are critical to biogeochemical cycles. Little is known about the molecular exchanges that occur within multi-kingdom systems, since measuring the molecular (e.g., metabolite) transactions among interacting species is a major technical challenge. We used a combination of different spatially resolved mass spectrometry approaches, including matrix-assisted laser desorption/ionization (MALDI), laser-ablation electrospray ionization (LAESI), and liquid extraction surface analysis (LESA) to explore a variety of environmental interkingdom interactions. In some cases, these sources were coupled to high-mass-resolution mass spectrometers (e.g., 21 Tesla Fourier-transform ion cyclotron mass spectrometer) for high-confidence molecular formula annotations, whereas in other cases we utilized an ultrahigh-resolution pre-mass analysis ion mobility mass spectrometer for confident identification and localization of isomeric compounds. In many examples, we used optical microscopy methods for correlative analysis with our spatially resolved MS approaches, in an effort to link structural information with molecular localization and identification of metabolites. Using these approaches, we were able to determine the molecular location within multiple plant-based interkingdom interactions, where, for example, our results demonstrated (i) how metabolic asymmetry exists within specialized soybean root organs (i.e., nodules) as a function of the plant’s symbiosis with soil bacteria capable of fixing nitrogen, (ii) how a Pinus species was able to change the alkaloid profile within its roots in response to mycorrhization, and (iii) how disaccharide profiles changes within a Sphagnum (peat moss) microbiome. Employing LAESI has allowed us to molecularly profile native plant tissue and has thus shown promise in high-throughput spatial metabolomics of living plants down to the single-cell level. We are currently developing new sampling methods that will allow us to temporally map the metabolome of rhizospheres and soil microbiomes in field-like settings with MS imaging and other imaging modalities.
Chris received his Bachelor of Science degree in chemistry at the University of Colorado at Colorado Springs in 2005. He attained his PhD in chemistry at the University of Illinois at Urbana–Champaign in 2011, under Mary L. Kraft, where his graduate work focused on using secondary ion mass spectrometry (ToF-SIMS and NanoSIMS) in conjunction with atomic force microscopy and scanning electron microscopy for multi-technique correlative analysis of supported lipid membranes. Afterward, he received a US National Research Council Postdoctoral Associateship to work at the National Institute of Standards and Technology under Anne L. Plant, where he studied how eukaryotic cells respond to changes in the physicochemical properties of their extracellular environment, using force microscopy, fluorescence microscopy, and ToF-SIMS. In 2013, he joined the Mass Spectrometry Group at the Environmental Molecular Sciences Laboratory, where he currently focuses on developing new mass spectrometry imaging instrumentation and capabilities to elucidate chemical interactions occurring within microbial communities, soils, and the rhizosphere.
Mass Spectrometry Imaging and Spatial Metabolomics
University of Illinois at Urbana-Champaign, PhD Chemistry
University of Colorado at Colorado Springs, BS Chemistry