Abstract
BackgroundDiet-derived short-chain fatty acids (SCFAs) in the rumen have broad effects on the health and growth of ruminants. The microbe-G-protein-coupled receptor (GPR) and microbe-histone deacetylase (HDAC) axes might be the major pathway mediating these effects. Here, an integrated approach of transcriptome sequencing and 16S rRNA gene sequencing was applied to investigate the synergetic responses of rumen epithelium and rumen microbiota to the increased intake of dietary non-fiber carbohydrate (NFC) from 15 to 30% in the goat model. In addition to the analysis of the microbial composition and identification of the genes and signaling pathways related to the differentially expressed GPRs and HDACs, the combined data including the expression of HDACs and GPRs, the relative abundance of the bacteria, and the molar proportions of the individual SCFAs were used to identify the significant co-variation of the SCFAs, clades, and transcripts.ResultsThe major bacterial clades promoted by the 30% NFC diet were related to lactate metabolism and cellulose degradation in the rumen. The predominant functions of the GPR and HDAC regulation network, under the 30% NFC diet, were related to the maintenance of epithelium integrity and the promotion of animal growth. In addition, the molar proportion of butyrate was inversely correlated with the expression of HDAC1, and the relative abundance of the bacteria belonging to Clostridum_IV was positively correlated with the expression of GPR1.ConclusionsThis study revealed that the effects of rumen microbiota-derived SCFA on epithelium growth and metabolism were mediated by the GPR and HDAC regulation network. An understanding of these mechanisms and their relationships to dietary components provides better insights into the modulation of ruminal fermentation and metabolism in the promotion of livestock production.
Highlights
Diet-derived short-chain fatty acids (SCFAs) in the rumen have broad effects on the health and growth of ruminants
Dimensionality reduction for microbial features and multidata integration In order to improve power to associate microbial composition with host gene transcriptional activity, we reduced the dimensionality of microbial features through calculating their spearman correlation coefficient (SCC) with the molar proportions of individual SCFAs, since the molar proportions of SCFAs were stable across the time within the group
Since the highly conserved sequences of these genes within vertebrates, our results indicate the possibility that commensal bacteria regulate the epithelium physiology via metabolite-mediated G-protein-coupled receptor (GPR) and histone deacetylase (HDAC) pathways in the rumen
Summary
Diet-derived short-chain fatty acids (SCFAs) in the rumen have broad effects on the health and growth of ruminants. An integrated approach of transcriptome sequencing and 16S rRNA gene sequencing was applied to investigate the synergetic responses of rumen epithelium and rumen microbiota to the increased intake of dietary non-fiber carbohydrate (NFC) from 15 to 30% in the goat model. Global gene expression profiling, in a study of bovine rumen epithelium cell cultures, has shown that exogenous butyrate promotes the expression of genes associated with cell growth, signal transduction, and immune responses [4]. By dietary intervention and ruminal butyrate infusion, our in vivo investigations have demonstrated that SCFAs promote the expression of genes involved in epithelium growth and SCFA transport [5, 6]
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