Inflammatory Bowel Diseases (IBD), such as Crohn's disease and ulcerative colitis, are a major public health problem. These pathologies are characterized by chronic inflammatory flare-ups leading to severe intestinal damages.1 Branched-chain fatty acids (BCFAs) are metabolites naturally produced by the gut microbiota that were recently shown to have anti-inflammatory properties in vitro.2 The identification of BCFA-producing bacteria is of prime importance since these microorganisms may constitute promising probiotic strains to dampen inflammation in IBD patients. To evaluate the ability of gut bacteria to produce BCFA, a gas chromatography-mass spectrometry quantitative analysis has been implemented based on methods previously developed for short-chain fatty acids (SCFAs).3,4 Bacterial supernatants were acidified (HCl), and the BCFA extracted by liquid-liquid extraction (LLE) with methyl tert-butyl ether (MTBE). The extracts were analyzed by gas chromatography-mass spectrometry (GC-MS), without derivation step, using a high-polarity polyethylene glycol (PEG) type column in selected ion monitoring (SIM) mode. Quantification was performed using deuterated internal standards and external calibration curves. This method was used to screen more than one hundred gut bacterial strains, isolated from human healthy volunteers, and led to the identification of about 20 BCFA-producing bacteria.

 

 

1. Chang, J.T. N Engl J Med, 2020, 383(27), 2652.

2. Ezzine, C., Loison, L., Montbrion, N., Bole-Feysot, C., Dechelotte, P., Coeffier, M., Ribet, D. Gut Microbes, 2022, 14(1), 2108280.

3. Kim, K. S., Lee, Y., Chae, W., Cho, J. Y.  Metabolites, 2022, 12(6), 525.

4. Rohde, J. K., Fuh, M. M., Evangelakos, I., Pauly, M. J., Schaltenberg, N., Siracusa, F., Gagliani, N., Todter, K., Heeren, J., Worthmann, A. Metabolites, 2022, 12(2), 170.