A higher butyrate-generation capacity of water-extractable substrates from wheat bran as evidenced by in vitro and in vivo fermentation

Gut microbiota is influenced by the dietary composition and plays important roles in the pathogenesis of metabolic disorders. Thus, wheat bran extract was prepared by either water extraction or enzymatic pre-treatment extraction (referred as AEWB and EHWB, respectively), and then their corresponding impact on short-chain fatty acids generation and gut microbiota was investigated via both in vitro fermentation model and in vivo diabetic animal model. The results of in vitro model indicated that EHWB enhanced the abundance of Megamonas and Faecalibacterium, as well as the amino acids metabolism, which was consistent with the increased butyrate and amino acids metabolites (e.g. iso-butyrate and valerate). The diabetic model analysis suggested that the rats also had an increased amino acid metabolism due to the decreased pathways of amino acid biosynthesis and increased pathways of amino acid degradation following the EHWB intervention. Importantly, the current study revealed that the EHWB intervention led to a greater level of butyrate in the diabetic animal model compared to other groups, demonstrating its prebiotic function, which was supported by the positive correlation between butyrate level and abundance of Bifidobacterium and Lactobacillus. The above results indicated that the main components in water-extractable substrates played key roles in improving the gut microbiota profile and the key metabolite in terms of butyrate. This study might highlight a new ingredient for food industry with physiological functionality.