FT-IR Spectroscopic Analysis in tandem with chemometric tools for the characterization of Cecal Content of Mice: Effects of High Fat Diet and Beer

Metabolite profiles associated with the gut microbiota offer valuable insights into the influence of lifestyle and dietary factors on both health and diseases in animal models and in humans. In recent years, infrared spectroscopy has been demonstrated to be a valuable tool to investigate fecal and cecal content [1-5]. This study focuses on investigating the metabolite composition of mice cecal content using a fast and novel Fourier-transform infrared spectroscopy (FT-IR) method that involves the deposition of samples onto polypropylene sheets, enabling efficient analysis and characterization of metabolites and offering advantages such as requiring small sample quantities and minimal preparation steps [6]. Experimental procedures included extracting the cecal content, preparing the sample, and depositing it onto polypropylene sheets before and after filtration in 3 kDa microfiltration units. The FT-IR spectra were acquired using a high-resolution FT-IR spectrometer equipped with an attenuated total reflection (ATR) accessory. Preliminary results of principal component analysis (PCA) of the FT-IR spectra demonstrate the feasibility and efficiency of the method to characterize low molecular weight (LMW) metabolites and biomolecules in mice cecal content. Distinctive spectral features corresponding to various metabolites were observed in four groups of mice reared for 10 weeks in the following conditions: they were fed with standard diet (19% proteins, 6% fibers, 7% minerals and vitamins moisture, 64% carbohydrates and 4% fats), high-fat diet (26% proteins, 6 % fibers, 7% minerals and vitamins moisture, 26% carbohydrates and 35% fats); standard diet + 0.23% beer; high-fat diet + 0.23% beer. Our findings suggest diet-induced variations in the high and low molecular weight metabolite profiles and showcase the potential of the developed method for studying the impact of diet on gut metabolism. Further analysis and the interpretation of FT-IR spectra will be conducted using also other complementary techniques to identify specific metabolites and elucidate their variations among the different diet groups. FT-IR method with the deposition on polypropylene sheets provides a valuable tool for the efficient, low-cost, and reliable characterization of cecal content metabolites, eventually contributing to the understanding of the effects of healthy lifestyles on gut composition and metabolism.