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Background Dietary fibers are widely considered to be beneficial to health as they produce nutrients through gut microbial fermentation while facilitating weight management and boosting gut health. To date, the gene expression profiles of the carbohydrate active enzymes (CAZymes) that respond to different types of fibers (raw potato starch, RPS; inulin, INU; pectin, PEC) in the gut microbes of pigs are not well understood. Therefore, we investigated the functional response of colonic microbiota to different dietary fibers in pigs through metatranscriptomic analysis. Results The results showed that the microbial composition and CAZyme structure of the three experimental groups changed significantly compared with the control group (CON). Based on a comparative analysis with the control diet, RPS increased the abundance of Parabacteroides, Ruminococcus, Faecalibacterium and Alloprevotella but decreased Sutterella; INU increased the relative abundance of Fusobacterium and Rhodococcus but decreased Bacillus; and PEC increased the relative abundance of the Streptococcus and Bacteroidetes groups but decreased Clostridium, Clostridioides, Intestinibacter, Gemmiger, Muribaculum and Vibrio. The gene expression of CAZymes GH8, GH14, GH24, GH38, GT14, GT31, GT77 and GT91 downregulated but that of GH77, GH97, GT3, GT10 and GT27 upregulated in the RPS diet group; the gene expression of AA4, AA7, GH14, GH15, GH24, GH26, GH27, GH38, GH101, GT26, GT27 and GT38 downregulated in the INU group; and the gene expression of PL4, AA1, GT32, GH18, GH37, GH101 and GH112 downregulated but that of CE14, AA3, AA12, GH5, GH102 and GH103 upregulated in the PEC group. Compared with the RPS and INU groups, the composition of colonic microbiota in the PEC group exhibited more diverse changes with the variation of CAZymes and Streptococcus as the main contributor to CBM61, which greatly promoted the digestion of pectin. Conclusion The results of this exploratory study provided a comprehensive overview of the effects of different fibers on nutrient digestibility, gut microbiota and CAZymes in pig colon, which will furnish new insights into the impacts of the use of dietary fibers on animal and human health.

Background Dietary fibers are widely considered to be beneficial for health by producing nutrients by gut microbial fermentation while helping with weight management and gut health. So far, the gene expression profiles of CAZymes responsing to different type of fibers (raw potato starch, RPS; inulin, INU; pectin, PEC) in the gut microbes of pigs are not well understood. Therefore, we investigate the functional response of colonic microbiota to different dietary fibers in pigs based on metatranscriptomic analysis. Results Results showed that the microbial composition and carbohydrate active enzymes (CAZymes) structure of three experimental groups changed significantly compared to the control group (CON). As determined by comparative analysis with the control diet, RPS increased the abundances of Parabacteroides, Ruminococcus, Faecalibacterium and Alloprevotella, and decreased Sutterella. INU increased the relative abundance of Fusobacterium and Rhodococcus, while decreased Bacillus. And pectin treatment increased the relative abundance of Streptococcus and Bacteroidetes group, while decreased the relative abundance of Clostridium, Clostridioides, Intestinibacter, Gemmiger, Muribaculum, and Vibrio. The gene expression of CAZymes GH8, GH14, GH24, GH38, GT14, GT31, GT77 and GT91 downregulated while GH77, GH97, GT3, GT10 and GT27 upregulated in the RPS diet group; AA4, AA7, GH14, GH15, GH24, GH26, GH27, GH38, GH101, GT26, GT27 and GT38 downregulated in the INU group; as to the PEC group, the gene expression of PL4, AA1, GT32, GH18, GH37, GH101, and GH112 downregulated while CE14, AA3, AA12, GH5, GH102 and GH103 upregulated. Compared to RPS and INU groups, the composition of colonic microbiota in the PEC group had more diverse changes with the variation of carbohydrate active enzymes and Streptococcus as the main contributor to CBM61, which promoted the digestion of pectin greatly. Conclusions The results of this exploratory study displayed a comprehensive overview on the effects of different fibers on gut microbiota and CAZymes in pig colons, which will provide new insights into the impacts of the use of dietary fibers on animal or human health.

The objective of this study was to elucidate the impacts of irregular eating patterns on gut microbiota and transcriptomic responses in a pig model with different feeding regimens. The experiment involved 24 growing pigs (Duroc × Landrace × Large White, 48 days of age) which were randomly allocated to one of three feeding patterns: one-meal (M1), three-meals (M3), or five-meals (M5) per day with the same daily feed intake. The results showed that different feeding frequencies had no significant effects on the microbial composition of ileal digesta, colonic digesta, colon mucosa, as well as the concentration of SCFAs in colonic digesta. Mucosa transcriptomic profiling data showed the pathways related to vitamin metabolism were enriched in the ileum and colon of pigs in the pairwise comparison between M3 and M1 groups. On the other hand, the pathways related to lipid metabolism were enriched in the ileum and colon of pigs in the pairwise comparison between M5 and M1 groups. Lastly, the pathways related to protein metabolism were enriched in the colon in the pairwise comparison between M3 and M1 groups, M5 and M1 groups, M5 and M3 groups, while the ileum was not enriched. Differentially expressed genes (DEG) related to metabolism showed that carbohydrate transport was suppressed in the ileum and enhanced in the colon in M5 and M3 groups compared with the M1 group. Compared with the M3 group, carbohydrate transport in the ileum was enhanced in the M5 group, while in the colon was inhibited. With the increase of feeding frequency, the catabolism, biosynthesis, and transport of lipid in the ileum were suppressed, while those in the colon were enhanced. Compared with the M1 group, amino acid transport in the ileum and colon in the M3 group was enhanced. Amino acid catabolism in the ileum in the M5 group was enhanced compared with M1 and M3 groups. In summary, different feeding frequencies affected the transport of carbohydrate, lipid, and amino acid in the ileum and colon, and affected the catabolism and biosynthesis of lipid in the ileum and colon with a low impact on intestinal microbiota.