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Effect of supplementation of a minimal culture medium with inulin, corn fiber and pectin, compared with a glucose condition, on the gene expression of a set of bacteria of the intestinal microbiota

ABSTRACT: The aim of this RNA-sequencing study is to measure differential gene expression in 4 intestinal bacteria (Bacteroides xylanisolvens, Bacteroides thetaiotaomicron, Subdoligranulum variabile and Roseburia intestinalis). The data highlight the coordinated action of genes within the same locus involved in the degradation of complex carbohydrates. These loci are well characterized in Bacteroidetes species and referred to as polysaccharide utilization loci. In Firmicutes species, these loci are not so clear-cut, athough the GP-PUL concept has already been proposed. Here we compare the differential gene expression in minimal culture medium supplemented with a complex carbohydrate with a minimal culture medium supplemented with glucose. This differential analysis reveals a source-specific genetic response and a coordinated expression of genes involved in carbohydrate transport, carbohydrate degradation and transcriptional activation of these complex enzymatic machineries.

ORGANISM(S): Subdoligranulum variabile Roseburia intestinalis Bacteroides thetaiotaomicron Bacteroides xylanisolvens

PROVIDER: GSE237111 | GEO | 2023/12/01

REPOSITORIES: GEO

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Project description:The phylum Bacteroidetes is a major component of the human gut microbiota which has a broad impact on the development and physiology of its host, and a potential role in a wide range of disease syndromes1-3. The predominance of Bacteroidetes and the genus Bacteroides in the distal gut is due in large part to the expansion of paralogous gene clusters, termed Polysaccharide Utilization Loci (PULs), dedicated to the uptake and catabolism of host derived and dietary polysaccharides4,5. It is generally thought that the diversity of PULs is key to Bacteroides successful competition for nutrients in the gut environment6. The nutritive value of the available polysaccharides varies greatly and thus their utilization is hierarchical and strictly controlled. A typical PUL includes regulatory genes that control expression in response to the presence of specific glycan substrates. However the existence of additional regulatory mechanisms has been predicted to explain phenomena such as the hierarchical control, catabolite repression, and the fine tuning of gene expression to match catabolic activity7-9. Using Bacteroides fragilis as a model organism, this report describes a previously unknown layer of regulatory control in which cis-encoded antisense small RNAs (sRNA) act as repressors of the PULsâ catabolic genes. Nearly 30% of B. fragilis PULs are subject to this type of sRNA control and these PULs tend to be more closely linked to the utilization of host-derived glycans than dietary polysaccharides. The findings described here indicate the presence of a global control mechanism that underlies the known regulatory circuits which modulate PUL expression in response to substrate availability, and hence provide novel insight into regulation of the gut Bacteroidetes physiology. This is a 4 chip study with 8 technical replicates on each chip. This was an in vitro, exploratory study to determine if mutation or overexpression of a sRNA associated with the Don locus would affect gene expression. In vitro cultures were grown in defined media with mucin glycans as the sole carbon source. The two chips representing growth of the wild type strain (638R) on mucin glycans were also used in a related study GSE53883 (GSM1303101 and GSM1303102).

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Effect of supplementation of a minimal culture medium with inulin, corn fiber and pectin, compared with a glucose condition, on the gene expression of a set of bacteria of the intestinal microbiota

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