Metagenomic Insights into the Degradation of Resistant Starch by Human Gut Microbiota

Abstract

Several studies monitoring alterations in the community structure upon resistant starch (RS) interventions are available, although comprehensive function-based analyses are lacking. Recently, a multiomics approach based on 16S rRNA gene sequencing, metaproteomics, and metabolomics on fecal samples from individuals subjected to high and low doses of type 2 RS (RS2; 48 g and 3 g/2,500 kcal, respectively, daily for 2 weeks) in a crossover intervention experiment was performed. In the present study, we did pathway-based metagenomic analyses on samples from a subset of individuals (n= 12) from that study to obtain additional detailed insights into the functional structure at high resolution during RS2 intervention. A mechanistic framework based on obtained results is proposed where primary degradation was governed byFirmicutes, withRuminococcus bromiias a major taxon involved, providing fermentation substrates and increased acetate concentrations for the growth of various major butyrate producers exhibiting the enzyme butyryl-coenzyme A (CoA):acetate CoA-transferase. H2-scavenging sulfite reducers and acetogens concurrently increased. Individual responses of gut microbiota were noted, where seven of the 12 participants displayed all features of the outlined pattern, whereas four individuals showed mixed behavior and one subject was unresponsive. Intervention order did not affect the outcome, emphasizing a constant substrate supply for maintaining specific functional communities.IMPORTANCEManipulation of gut microbiota is increasingly recognized as a promising approach to reduce various noncommunicable diseases, such as obesity and type 2 diabetes. Specific dietary supplements, including resistant starches (RS), are often a focus, yet comprehensive insights into functional responses of microbiota are largely lacking. Furthermore, unresponsiveness in certain individuals is poorly understood. Our data indicate that distinct parts of microbiota work jointly to degrade RS and successively form health-promoting fermentation end products. It highlights the need to consider both primary degraders and specific more-downstream-acting bacterial groups in order to achieve desired intervention outcomes. The gained insights will assist the design of personalized treatment strategies based on an individual's microbiota.

Ingestion of resistant starch by mice markedly increases microbiome‐derived metabolites

“…The complex carbohydrates that constitute the fiber are mostly nondigestible by the host because of their unique chemical structure and physical properties, which allow them to reach the large intestine where they are subjected to fermentation into the short chain fatty acids (SCFAs) acetate, butyrate, and propionate (4). Although it is evident that only a subset of gut bacteria are stimulated by each type of dietary fiber [e.g., resistant starch (RS), inulin, pectin, and gums], it is not clear what specific enzymatic or substratebinding capabilities confer this (5).…”

Reconstruction and dynamics of human intestinal microbiome observedin situ

“…Bacterial species as well as metabolic pathways can have distinct patterns when they are examined at DNA (“standing”) level and RNA (“active”) levels 25, 26 . In defecated fecal samples, a collection of bacterial species including Ruminococcus , Subdoligranulum and Faecalibacterium are highly active in terms of transcription and potentially metabolism, and they belong to the increasingly well-appreciated group of butyrate producers, and butyrate is known to be both metabolically as well as immunologically crucial for the host, especially in the context of several metabolic as well as auto-immune disorders 28, 29, 30, 31 . Except the top pathway being adenosine ribonucleotides de novo biosynthesis that is related to ATP production and thus energy cycling in both DNA and RNA, metabolic pathways related to nutrients metabolism (for instance glucose metabolism) are highly active in transcriptome data, even though pathways related cellular structures (for instance, components of cell walls) are most abundant in DNAs, suggesting a heterogeneous regulation of transcription in pathways aimed at different parts of microbial physiological activities.…”

Effect of Resistant Starch on Inflammatory Bowel Diseases and Microbiota

“…Bütirat üreten Eubacterium rectale ve Roseburia spp., yüksek doz dirençli nişasta alanlarda yükselmiştir. 38…”