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Tannock GW. Understanding the gut microbiota by considering human evolution: a story of fire, cereals, cooking, molecular ingenuity, and functional cooperation. Microbiol Mol Biol Rev 2024; 88:e0012722. [PMID: 38126754 PMCID: PMC10966955 DOI: 10.1128/mmbr.00127-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023] Open
Abstract
SUMMARYThe microbial community inhabiting the human colon, referred to as the gut microbiota, is mostly composed of bacterial species that, through extensive metabolic networking, degrade and ferment components of food and human secretions. The taxonomic composition of the microbiota has been extensively investigated in metagenomic studies that have also revealed details of molecular processes by which common components of the human diet are metabolized by specific members of the microbiota. Most studies of the gut microbiota aim to detect deviations in microbiota composition in patients relative to controls in the hope of showing that some diseases and conditions are due to or exacerbated by alterations to the gut microbiota. The aim of this review is to consider the gut microbiota in relation to the evolution of Homo sapiens which was heavily influenced by the consumption of a nutrient-dense non-arboreal diet, limited gut storage capacity, and acquisition of skills relating to mastering fire, cooking, and cultivation of cereal crops. The review delves into the past to gain an appreciation of what is important in the present. A holistic view of "healthy" microbiota function is proposed based on the evolutionary pathway shared by humans and gut microbes.
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Affiliation(s)
- Gerald W. Tannock
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
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2
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Chiang BH, Vega G, Dunwoody SC, Patnode ML. Bacterial interactions on nutrient-rich surfaces in the gut lumen. Infect Immun 2024:e0048023. [PMID: 38506518 DOI: 10.1128/iai.00480-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024] Open
Abstract
The intestinal lumen is a turbulent, semi-fluid landscape where microbial cells and nutrient-rich particles are distributed with high heterogeneity. Major questions regarding the basic physical structure of this dynamic microbial ecosystem remain unanswered. Most gut microbes are non-motile, and it is unclear how they achieve optimum localization relative to concentrated aggregations of dietary glycans that serve as their primary source of energy. In addition, a random spatial arrangement of cells in this environment is predicted to limit sustained interactions that drive co-evolution of microbial genomes. The ecological consequences of random versus organized microbial localization have the potential to control both the metabolic outputs of the microbiota and the propensity for enteric pathogens to participate in proximity-dependent microbial interactions. Here, we review evidence suggesting that several bacterial species adopt organized spatial arrangements in the gut via adhesion. We highlight examples where localization could contribute to antagonism or metabolic interdependency in nutrient degradation, and we discuss imaging- and sequencing-based technologies that have been used to assess the spatial positions of cells within complex microbial communities.
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Affiliation(s)
- Bo Huey Chiang
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, California, USA
- Graduate Program in Biological Sciences and Engineering, University of California, Santa Cruz, California, USA
| | - Giovanni Vega
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, California, USA
- Graduate Program in Biological Sciences and Engineering, University of California, Santa Cruz, California, USA
| | - Sarah C Dunwoody
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, California, USA
| | - Michael L Patnode
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, California, USA
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3
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Smith AD, Chen C, Cheung L, Ward RE, Jones BS, Pletsch EA, Dawson HD. A type 4 resistant potato starch alters the cecal microbiome and gene expression in mice fed a western diet based on NHANES data. Food Funct 2024; 15:3141-3157. [PMID: 38439638 DOI: 10.1039/d3fo04512a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2024]
Abstract
Four major types of resistant starch (RS1-4) are present in foods, all of which can alter the microbiome and are fermented in the cecum and colon to produce short-chain fatty acids (SCFAs). Type 4 RSs are chemically modified starches, not normally found in foods, but have become a popular food additive as their addition increases fiber content. Multiple studies, in humans and rodents, have explored how different RS4 affect post-prandial glucose metabolism, but fewer studies have examined the effects of RS4 consumption on the microbiome. In addition, many RS studies conducted in rodents use high-fat diets that do not approximate what is typically consumed by humans. To address this, mice were fed a Total Western Diet (TWD), based on National Health and Nutrition Examination Survey (NHANES) data that mimics the macro and micronutrient composition of a typical American diet, for six weeks, and then supplemented with 0, 2, 5, or 10% of the RS4, Versafibe 1490™ (VF), a phosphorylated and cross-linked potato starch, for an additional three weeks. The cecal contents were analyzed for SCFA content and microbiota composition. Butyrate production was increased while branched chain SCFA production decreased. The alpha-diversity of the microbiome decreased in mice fed the TWD with 10% VF 1490 added while the beta-diversity plot showed that the 5% and 10% VF groups were distinct from mice fed the TWD. Similarly, the largest changes in relative abundance of various genera were greatest in mice fed the 10% VF diet. To examine the effect of VF consumption on tissue gene expression, cecal and distal colon tissue mRNA abundance were analyzed by RNASeq. Gene expression changes were more prevalent in the cecum than the colon and in mice fed the 10% VF diet, but the number of changes was substantially lower than we previously observed in mice fed the TWD supplemented with native potato starch (RPS). These results provide additional evidence that the structure of the RS is a major factor determining its effects on the microbiome and gene expression in the cecum and colon.
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Affiliation(s)
- Allen D Smith
- Diet, Genomics, and Immunology Laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, United States Department of Agriculture, Rm. 228, Bldg. 307C, BARC-East, 10, 300 Baltimore Ave., Beltsville, MD, 20705, USA.
| | - Celine Chen
- Diet, Genomics, and Immunology Laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, United States Department of Agriculture, Rm. 228, Bldg. 307C, BARC-East, 10, 300 Baltimore Ave., Beltsville, MD, 20705, USA.
| | - Lumei Cheung
- Diet, Genomics, and Immunology Laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, United States Department of Agriculture, Rm. 228, Bldg. 307C, BARC-East, 10, 300 Baltimore Ave., Beltsville, MD, 20705, USA.
| | - Robert E Ward
- Department of Nutrition, Dietetics and Food Sciences, Utah State University, USA
| | - B Sky Jones
- Department of Nutrition, Dietetics and Food Sciences, Utah State University, USA
| | - Elizabeth A Pletsch
- Diet, Genomics, and Immunology Laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, United States Department of Agriculture, Rm. 228, Bldg. 307C, BARC-East, 10, 300 Baltimore Ave., Beltsville, MD, 20705, USA.
| | - Harry D Dawson
- Diet, Genomics, and Immunology Laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, United States Department of Agriculture, Rm. 228, Bldg. 307C, BARC-East, 10, 300 Baltimore Ave., Beltsville, MD, 20705, USA.
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Wong JPH, Chillier N, Fischer-Stettler M, Zeeman SC, Battin TJ, Persat A. Bacteroides thetaiotaomicron metabolic activity decreases with polysaccharide molecular weight. mBio 2024; 15:e0259923. [PMID: 38376161 PMCID: PMC10936149 DOI: 10.1128/mbio.02599-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 01/26/2024] [Indexed: 02/21/2024] Open
Abstract
The human colon hosts hundreds of commensal bacterial species, many of which ferment complex dietary carbohydrates. To transform these fibers into metabolically accessible compounds, microbes often express a series of dedicated enzymes homologous to the starch utilization system (Sus) encoded in polysaccharide utilization loci (PULs). The genome of Bacteroides thetaiotaomicron (Bt), a common member of the human gut microbiota, encodes nearly 100 PULs, conferring a strong metabolic versatility. While the structures and functions of individual enzymes within the PULs have been investigated, little is known about how polysaccharide complexity impacts the function of Sus-like systems. We here show that the activity of Sus-like systems depends on polysaccharide size, ultimately impacting bacterial growth. We demonstrate the effect of size-dependent metabolism in the context of dextran metabolism driven by the specific utilization system PUL48. We find that as the molecular weight of dextran increases, Bt growth rate decreases and lag time increases. At the enzymatic level, the dextranase BT3087, a glycoside hydrolase (GH) belonging to the GH family 66, is the main GH for dextran utilization, and BT3087 and BT3088 contribute to Bt dextran metabolism in a size-dependent manner. Finally, we show that the polysaccharide size-dependent metabolism of Bt impacts its metabolic output in a way that modulates the composition of a producer-consumer community it forms with Bacteroides fragilis. Altogether, our results expose an overlooked aspect of Bt metabolism that can impact the composition and diversity of microbiota. IMPORTANCE Polysaccharides are complex molecules that are commonly found in our diet. While humans lack the ability to degrade many polysaccharides, their intestinal microbiota contain bacterial commensals that are versatile polysaccharide utilizers. The gut commensal Bacteroides thetaiotaomicron dedicates roughly 20% of their genomes to the expression of polysaccharide utilization loci for the broad range utilization of polysaccharides. Although it is known that different polysaccharide utilization loci are dedicated to the degradation of specific polysaccharides with unique glycosidic linkages and monosaccharide compositions, it is often overlooked that specific polysaccharides may also exist in various molecular weights. These different physical attributes may impact their processability by starch utilization system-like systems, leading to differing growth rates and nutrient-sharing properties at the community level. Therefore, understanding how molecular weight impacts utilization by gut microbe may lead to the potential design of novel precision prebiotics.
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Affiliation(s)
- Jeremy P. H. Wong
- Institute of Bioengineering and Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Sion, Switzerland
| | - Noémie Chillier
- Institute of Bioengineering and Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | | | | | - Tom J. Battin
- School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Sion, Switzerland
| | - Alexandre Persat
- Institute of Bioengineering and Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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Photenhauer AL, Villafuerte-Vega RC, Cerqueira FM, Armbruster KM, Mareček F, Chen T, Wawrzak Z, Hopkins JB, Vander Kooi CW, Janeček Š, Ruotolo BT, Koropatkin NM. The Ruminococcus bromii amylosome protein Sas6 binds single and double helical α-glucan structures in starch. Nat Struct Mol Biol 2024; 31:255-265. [PMID: 38177679 PMCID: PMC11081458 DOI: 10.1038/s41594-023-01166-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 10/27/2023] [Indexed: 01/06/2024]
Abstract
Resistant starch is a prebiotic accessed by gut bacteria with specialized amylases and starch-binding proteins. The human gut symbiont Ruminococcus bromii expresses Sas6 (Starch Adherence System member 6), which consists of two starch-specific carbohydrate-binding modules from family 26 (RbCBM26) and family 74 (RbCBM74). Here, we present the crystal structures of Sas6 and of RbCBM74 bound with a double helical dimer of maltodecaose. The RbCBM74 starch-binding groove complements the double helical α-glucan geometry of amylopectin, suggesting that this module selects this feature in starch granules. Isothermal titration calorimetry and native mass spectrometry demonstrate that RbCBM74 recognizes longer single and double helical α-glucans, while RbCBM26 binds short maltooligosaccharides. Bioinformatic analysis supports the conservation of the amylopectin-targeting platform in CBM74s from resistant-starch degrading bacteria. Our results suggest that RbCBM74 and RbCBM26 within Sas6 recognize discrete aspects of the starch granule, providing molecular insight into how this structure is accommodated by gut bacteria.
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Affiliation(s)
- Amanda L Photenhauer
- Department of Microbiology & Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | | | - Filipe M Cerqueira
- Department of Microbiology & Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Krista M Armbruster
- Department of Microbiology & Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Filip Mareček
- Laboratory of Protein Evolution, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Tiantian Chen
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Zdzislaw Wawrzak
- Northwestern Synchrotron Research Center-LS-CAT, Northwestern University, Argonne, IL, USA
| | - Jesse B Hopkins
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological, Chemical, and Physical Sciences, Illinois Institute of Technology, Chicago, IL, USA
| | - Craig W Vander Kooi
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Štefan Janeček
- Laboratory of Protein Evolution, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia
| | | | - Nicole M Koropatkin
- Department of Microbiology & Immunology, University of Michigan Medical School, Ann Arbor, MI, USA.
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6
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Pickens TL, Cockburn DW. Clostridium butyricum Prazmowski can degrade and utilize resistant starch via a set of synergistically acting enzymes. mSphere 2024; 9:e0056623. [PMID: 38131665 PMCID: PMC10826348 DOI: 10.1128/msphere.00566-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 11/28/2023] [Indexed: 12/23/2023] Open
Abstract
Resistant starch is a prebiotic fiber that is best known for its ability to increase butyrate production by the gut microbiota. This butyrate then plays an important role in modulating the immune system and inflammation. However, the ability to use this resistant starch appears to be a rare trait within the gut microbiota, with only a few species such as Ruminococcus bromii and Bifidobacterium adolescentis having been demonstrated to possess this ability. Furthermore, these bacteria do not directly produce butyrate themselves, rather they rely on cross-feeding interactions with other gut bacteria for its production. Here, we demonstrate that the often-used probiotic organism Clostridium butyricum also possesses the ability to utilize resistant starch from a number of sources, with direct production of butyrate. We further explore the enzymes responsible for this trait, demonstrating that they exhibit significant synergy, though with different enzymes exhibiting more or less importance depending on the source of the resistant starch. Thus, the co-administration of Clostridium butyricum may have the ability to improve the beneficial effects of resistant starch.IMPORTANCEClostridium butyricum is seeing increased use as a probiotic, due to potential health benefits tied to its ability to produce butyrate. Here, we demonstrate that this organism can use a variety of resistant starch sources and characterize the enzymes it uses to accomplish this. Given the relative rarity of resistant starch utilizing ability within the gut and the health benefits tied to resistant starch, the combined use of this organism with resistant starch in synbiotic formulations may prove beneficial.
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Affiliation(s)
- Tara L. Pickens
- Department of Food Science, The Pennsylvania State University, State College, Pennsylvania, USA
- The One Health Microbiome Center, Huck Institute of the Life Sciences, The Pennsylvania State University, State College, Pennsylvania, USA
| | - Darrell W. Cockburn
- Department of Food Science, The Pennsylvania State University, State College, Pennsylvania, USA
- The One Health Microbiome Center, Huck Institute of the Life Sciences, The Pennsylvania State University, State College, Pennsylvania, USA
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7
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Brown HA, Koropatkin NM. Isothermal Titration Calorimetry for Quantification of Protein-Carbohydrate Interactions. Methods Mol Biol 2023; 2657:129-140. [PMID: 37149527 DOI: 10.1007/978-1-0716-3151-5_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Isothermal titration calorimetry allows the determination of thermodynamic parameters for the interaction between a protein and mono- or oligosaccharides in solution. For the study of protein-carbohydrate interactions, it is a robust way to determine the stoichiometry and affinity, as well as the enthalpic and entropic contributions to this interaction, without the use of labeled proteins or substrates. Here we describe a standard multiple-injection titration experiment for measuring the binding energetics between a carbohydrate-binding protein and an oligosaccharide.
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Affiliation(s)
- Haley A Brown
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Nicole M Koropatkin
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA.
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8
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Butyrate-producing colonic clostridia: picky glycan utilization specialists. Essays Biochem 2022; 67:415-428. [PMID: 36350044 DOI: 10.1042/ebc20220125] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 10/18/2022] [Accepted: 10/21/2022] [Indexed: 11/10/2022]
Abstract
Abstract
Butyrate-producing human gut microbiota members are recognized for their strong association with a healthy immune-homeostasis and protection from inflammatory disorders and colorectal cancer. These effects are attributed to butyrate, the terminal electron sink of glycan fermentation by prevalent and abundant colonic Firmicutes from the Lachnospiraceae and Oscillospiraceae families. Remarkably, our insight into the glycan utilization mechanisms and preferences of butyrogenic Firmicutes remains very limited as compared with other gut symbionts, especially from the Bacteroides, Bifidobacterium, and Lactobacillus genera. Here, we summarize recent findings on the strategies that colonic butyrate producers have evolved to harvest energy from major dietary fibres, especially plant structural and storage glycans, such as resistant starch, xylans, and mannans. Besides dietary fibre, we also present the unexpected discovery of a conserved protein apparatus that confers the growth of butyrate producers on human milk oligosaccharides (HMOs), which are unique to mother’s milk. The dual dietary fibre/HMO utilization machinery attests the adaptation of this group to both the infant and adult guts. These finding are discussed in relation to the early colonization of butyrogenic bacteria and the maturation of the microbiota during the transition from mother’s milk to solid food. To date, the described butyrogenic Firmicutes are glycan utilization specialists that target only a few glycans in a highly competitive manner relying on co-regulated glycan utilization loci. We describe the common pillars of this machinery, highlighting butyrate producers as a source for discovery of biochemically and structurally novel carbohydrate active enzymes.
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Abstract
Not all starches in the human diet are created equal: “resistant starches” are consolidated aggregates of the α-glucan polysaccharides amylose and amylopectin, which escape digestion by salivary and pancreatic amylases. Upon reaching the large intestine, resistant starches become fodder for members of the human gut microbiota, impacting the metabolism of both the symbionts and the host. In a recent study, Koropatkin et al. provided new molecular insight into how a keystone bacterium in the human gut microbiota adheres to resistant starches as a prelude to their breakdown and fermentation.
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