Rapid metabolomic profiling by 1H NMR imaging Trey Koev 1 , Hannah Harris 2 , Fred Warren 2 and Matthew Wallace 1 1 NMR Group, School of Pharmacy, University of East Anglia, 2 Food Innovation and Health, Quadram Institute Bioscience In vitro fermentation models have been a long-standing method for probing substrates’ propensity for fermentation, production of gas, and physiologically relevant metabolites, such as short-chain fatty acids (SCFAs). The primary SCFAs produced in the large intestine are acetate, butyrate and propionate 1 , with all three having important physiological roles in hepatic gluconeogenesis, influencing metabolic homeostasis markers, such as hormones PYY and GLP-1 2 , improving B-cell function, as well as insulin secretion. 3 Dysregulation of the production of these SCFAs has been linked to cardiovascular disease (CVD), metabolic syndrome, and diabetes mellitus. 4 However, most current in vitro fermentation models involve complex set-ups, featuring multiple vessels, frequent sampling, and often introducing oxygen to the anaerobic fermentation set-up, which may perturb the life cycle and metabolism of anaerobes and obligate anaerobes, such as Bacteroides , Faecalibacterium , and Ruminococcus . 5,6 In this work, we demonstrate a new, rapid semi-automated method for the spatially resolved quantification of small molecular metabolites directly in an NMR tube, with minimal sample preparation or sampling. Our method is based on the chemical shift imaging (CSI) methodology, developed by Wallace et al. 7 , and further allows for the dynamic and accurate determination of pH, as a function of fermentation time, which has been shown to be useful in the rapid diagnostics of colorectal pathologies and bacterial dysbiosis. References 1. S. H. Duncan, G. Holtrop, G. E. Lobley, A. G. Calder, C. S. Stewart and H. J. Flint, Br. J. Nutr. , 2004, 91 , 915–923. 2. J. G. Bloemen, K. Venema, M. C. van de Poll, S. W. Olde Damink, W. A. Buurman and C. H. Dejong, Clin. Nutr. , 2009, 28 , 657–661. 3. E. S. Chambers, D. J. Morrison, M. C. Tedford and G. Frost, Nutr. Bull. , 2015, 40 , 227–230. 4. E. S. Chambers, T. Preston, G. Frost and D. J. Morrison, Curr. Nutr. Rep. , 2018, 7 , 198–206. 5. X. Ze, S. H. Duncan, P. Louis and H. J. Flint, ISME J. , 2012, 6 , 1535–1543. 6. F. Asnicar, E. R. Leeming, E. Dimidi, M. Mazidi, P. W. Franks, H. Al Khatib, A. M. Valdes, R. Davies, E. Bakker, L. Francis, A. Chan, R. Gibson, G. Hadjigeorgiou, J. Wolf, T. D. Spector, N. Segata and S. E. Berry, Gut , 2021, 70 , 1665–1674. 7. M. Wallace, D. J. Adams and J. A. Iggo, Anal. Chem. , 2018, 90 , 4160–4166.
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