Environmental pH is a determinant of the gut microbiota community composition and production of short chain fatty acids

Authors: Firrman, Jenni; Liu, Linshu; Mahalak, Karley; TANES, CEYLAN - Children'S Hospital - Philadelphia, Pennsylvania; BITTINGER, KYLE - Children'S Hospital - Philadelphia, Pennsylvania; TU, VINCENT - Children'S Hospital - Philadelphia, Pennsylvania; BOBOKALONOV, JAMSHED - US Department Of Agriculture (USDA); MATTEI, LISA - Children'S Hospital - Philadelphia, Pennsylvania; ZHANG, HUANJIA - Children'S Hospital - Philadelphia, Pennsylvania; VAN DEN ABBEELE, PIETER - Prodigest

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/14/2021
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Within the colon, the gut microbiota functions to ferment polysaccharides and amino acids to produce short chain fatty acids (SCFAs) and branched-chain SCFAs. However, changes to environmental pH can shift the types and abundance of taxa that perform these functions and affect enzymatic activity. Here, incremental alterations of pH were applied to a gut microbial community in vitro to explicate the effect of pH on community composition and SCFAs production. First, multiple donors were screened to elucidate a donor-independent response. The results found that lowering pH decreased abundance of taxa within phylum Bacteroidetes and increased Firmicutes. These compositional changes corresponded with reduced levels of total SCFAs, specifically acetic, propanoic, and 2-methylbutanoic acids, yet increased levels of butyric and pentanoic acids. Raising pH increased abundance of Bacteroidetes Alistipes and decreased Firmicutes Megasphaera. This corresponded to increased levels of total SCFAs, acetic acid, and 2-methylbutanic acid, and decreased propionic and pentanoic acids. Next, a multicompartment model was used to determine the effect of pH on region-specific communities representing the ascending (AC), transverse (TC), and descending (DC) colons. Lowering pH decreased abundance of taxa within phylum Bacteroidetes in the AC, and decreased levels of Firmicutes Oscillospira and Fusobacterium Fusobacteria predominately in the TC and DC. This corresponded to a drop in total SCFAs, specifically, acetic and 3-methylbutanoic acids comprehensively, propanoic, butyric, 2-methylpropanoic, 2-methylbutanoic in the AC and TC, and pentanoic acid in the TC and DC. Raising pH increased abundance of Fusobacterium Fusobacteria and decreased Firmicutes Megasphaera comprehensively. This corresponded with decreased levels of pentanoic, butyric, 2-methylbutanoic, 3-methylbutanoic acids comprehensively, 2-methylpropanoic acid in the AC and DC, and total SCFAs in the DC only. Taken together, these results indicate that environmental pH can modulate the gut microbiota community structure and function, which plays an important role in human health and disease prevention.