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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #397924

Research Project: Analysis of Genetic Factors that Increase Foodborne Pathogen Fitness, Virulence, and Antimicrobial Resistance Transfer, to Identify Interventions against Salmonella and Campylobacter in Food Animals

Location: Food Safety and Enteric Pathogens Research

Title: On-tissue derivatization of volatile metabolites for matrix assisted laser desorption/ionization mass spectrometry imaging

item FORSMAN, TREVOR - Iowa State University
item PAULSON, ANDREW - Iowa State University
item LARSON, EVAN - Iowa State University
item Looft, Torey
item LEE, YOUNG JIN - Iowa State University

Submitted to: Journal of Mass Spectrometry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2023
Publication Date: 4/2/2023
Citation: Forsman, T.T., Paulson, A.E., Larson, E.A., Looft, T.P., Lee, Y. 2023. On-tissue derivatization of volatile metabolites for matrix assisted laser desorption/ionization mass spectrometry imaging. Journal of Mass Spectrometry. 58(5). Article e4918.

Interpretive Summary: Intestinal bacteria impact poultry health, including by the producing metabolites absorbed by birds. Short-chain fatty acids (SCFA) are an important class of beneficial metabolites, however they are difficult to detect in tissues because SCFA are often lost during sample preparation. Here we present a method (chemical derivatization) to stabilize SCFA on tissues before traditional sample preparation to improve SCFA detection. Tested on chicken intestinal tissues, this method improved the sensitivity of SCFA detection and allowed comparisons between tissues. SCFA differences can be detected using spatial mapping techniques, allowing researchers to identify regions of SCFA production and absorption. Focusing on regions where SCFA are produced and absorbed improves our understanding of microbial functions, and may suggest new targets for modulation to improve animal health and production.

Technical Abstract: Mass spectrometry imaging (MSI) of volatile metabolites is a challenging task, especially in matrixassisted laser desorption/ionization (MALDI). Most MALDI ion sources operate in vacuum, which leads to the vaporization of volatile metabolites during analysis. In addition, tissue samples are often dried under vacuum as a part of sample preparation, which leads to the loss of volatile metabolites even for other MSI techniques. As a result, most volatile metabolites have not been visualized by MSI including short-chain fatty acids (SCFAs), an important class of gut microbiome metabolites. On-tissue chemical derivatization is often used to improve the ionization of target analytes in MSI, but it can also dramatically minimize the volatility of analytes, which was not previously explored. Herein a derivatization method is proposed utilizing N,N,N-trimethyl-2-(piperazin-1-yl)ethan-1-aminium iodide to chemically modify SCFAs before sample preparation for MSI. Using this method, SCFAs were visualized in chicken cecum, ileum, and jejunum tissue sections, which was not possible without derivatization.