Abstract
The microorganisms that inhabit the human gastrointestinal tract comprise a complex ecosystem with functions that significantly contribute to our systemic metabolism and have an impact on ...health and disease. In line with its importance, the human gastrointestinal microbiota has been extensively studied. Despite the fact that a significant part of the intestinal microorganisms has not yet been cultured, presently over 1000 different microbial species that can reside in the human gastrointestinal tract have been identified. This review provides a systematic overview and detailed references of the total of 1057 intestinal species of Eukarya (92), Archaea (8) and Bacteria (957), based on the phylogenetic framework of their small subunit ribosomal RNA gene sequences. Moreover, it unifies knowledge about the prevalence, abundance, stability, physiology, genetics and the association with human health of these gastrointestinal microorganisms, which is currently scattered over a vast amount of literature published in the last 150 years. This detailed physiological and genetic information is expected to be instrumental in advancing our knowledge of the gastrointestinal microbiota. Moreover, it opens avenues for future comparative and functional metagenomic and other high-throughput approaches that need a systematic and physiological basis to have an impact.
This historical review summarizes the over 1000 species associated with the human gastrointestinal tract – it provides a systematic presentation of all currently recognized gastrointestinal tract Bacteria, Archaea and Eukarya coupled with the reports of their prevalence, abundance, their stability in the ecosystem, physiology, genetics, and association with human health.
While nature has optimized its antifouling strategies over millions of years, synthetic antifouling coatings have not yet reached technological maturity. For an antifouling coating to become ...technically feasible, it should fulfill many requirements: high effectiveness, long‐term stability, durability, ecofriendliness, large‐scale applicability, and more. It is therefore not surprising that the search for the perfect antifouling coating has been going on for decades. With the discovery of metal‐based antifouling paints in the 1970s, fouling was thought to be a problem of the past, yet its untargeted toxicity led to serious ecological concern, and its use became prohibited. As a response, research shifted focus toward a biocompatible alternative: polymer‐based antifouling coatings. This has resulted in numerous advanced and innovative antifouling strategies, including fouling‐resistant, fouling‐release, and fouling‐degrading coatings. Here, these novel and exciting discoveries are highlighted while simultaneously assessing their antifouling performance and practical feasibility.
Unwanted adhesion of material remains a widespread obstacle, causing problems in medical, marine, and industrial applications. Antifouling coatings are perhaps the most promising method for fouling control. In this work, novel antifouling coatings and strategies are highlighted, including a discussion of the hidden complexity of the coatings' stability, durability, and applicability.
Since the early days of the intestinal microbiota research, mouse models have been used frequently to study the interaction of microbes with their host. However, to translate the knowledge gained ...from mouse studies to a human situation, the major spatio-temporal similarities and differences between intestinal microbiota in mice and humans need to be considered. This is done here with specific attention for the comparative physiology of the intestinal tract, the effect of dietary patterns and differences in genetics. Detailed phylogenetic and metagenomic analysis showed that while many common genera are found in the human and murine intestine, these differ strongly in abundance and in total only 4% of the bacterial genes are found to share considerable identity. Moreover, a large variety of murine strains is available yet most of the microbiota research is performed in wild-type, inbred strains and their transgenic derivatives. It has become increasingly clear that the providers, rearing facilities and the genetic background of these mice have a significant impact on the microbial composition and this is illustrated with recent experimental data. This may affect the reproducibility of mouse microbiota studies and their conclusions. Hence, future studies should take these into account to truly show the effect of diet, genotype or environmental factors on the microbial composition.
Metabolic disorders associated with obesity and cardiometabolic disorders are worldwide epidemic. Among the different environmental factors, the gut microbiota is now considered as a key player ...interfering with energy metabolism and host susceptibility to several non-communicable diseases. Among the next-generation beneficial microbes that have been identified,
is a promising candidate. Indeed,
is inversely associated with obesity, diabetes, cardiometabolic diseases and low-grade inflammation. Besides the numerous correlations observed, a large body of evidence has demonstrated the causal beneficial impact of this bacterium in a variety of preclinical models. Translating these exciting observations to human would be the next logic step and it now appears that several obstacles that would prevent the use of
administration in humans have been overcome. Moreover, several lines of evidence indicate that pasteurization of
not only increases its stability but more importantly increases its efficacy. This strongly positions
in the forefront of next-generation candidates for developing novel food or pharma supplements with beneficial effects. Finally, a specific protein present on the outer membrane of
, termed Amuc_1100, could be strong candidate for future drug development. In conclusion, as plants and its related knowledge, known as pharmacognosy, have been the source for designing drugs over the last century, we propose that microbes and microbiomegnosy, or knowledge of our gut microbiome, can become a novel source of future therapies.
Akkermansia muciniphila is an intestinal bacterium that was isolated a decade ago from a human fecal sample. Its specialization in mucin degradation makes it a key organism at the mucosal interface ...between the lumen and host cells. Although it was isolated quite recently, it has rapidly raised significant interest as A. muciniphila is the only cultivated intestinal representative of the Verrucomicrobia, one of the few phyla in the human gut that can be easily detected in phylogenetic and metagenome analyses. There has also been a growing interest in A. muciniphila, due to its association with health in animals and humans. Notably, reduced levels of A. muciniphila have been observed in patients with inflammatory bowel diseases (mainly ulcerative colitis) and metabolic disorders, which suggests it may have potential anti-inflammatory properties. The aims of this review are to summarize the existing data on the intestinal distribution of A. muciniphila in health and disease, to provide insight into its ecology and its role in founding microbial networks at the mucosal interface, as well as to discuss recent research on its role in regulating host functions that are disturbed in various diseases, with a specific focus on metabolic disorders in both animals and humans.
•Akkermansia spp. are widely present in the intestinal tract of man and other animals.•A. spp. have been negatively associated with metabolic disorder in many clinical and preclinical studies.•Enrichment of Akkermansia following dietary or drug supplementation frequently coincides with improved metabolic parameters.•When administered alive, Akkermansia muciniphila protects mice from diet-induced obesity.
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•The intestinal microbiota follows a common successional pattern in early life.•Particular bacterial taxa are mainly transmitted from the mother to the infant after birth.•Infants ...receive specific bacterial signals at specific immunological time windows.•C-section and antibiotic use disrupt the colonization and development process explaining later life health impact.•Targeted treatment of age-specific microbial defects may offer novel ways to promote health.
Microbes colonising the infant intestine, especially bacteria, are considered important for metabolic and immunological programming in early life, potentially affecting the susceptibility of the host to disease. We combined published data to provide a global view of microbiota development in early life. The results support the concept that the microbiota develops with age in an orchestrated manner, showing common patterns across populations. Furthermore, infants are colonised at birth by specific, selected maternal faecal bacteria and likely their bacteriophages. Therefore, infants are adapted to receiving specific bacterial signals, partly derived from the maternal microbiota, at successive immunological time windows during early development. Birth by caesarean section compromises the initial vertical transmission of microbes whereas antibiotic use shifts the microbiota away from the normal developmental pattern. These disruptions alter the microbial signals that the host receives, potentially affecting child development.
Nonsolvent induced phase separation (NIPS) is the most common approach to produce polymeric membranes. Unfortunately, NIPS relies heavily on aprotic organic solvents like N‐methyl‐pyrrolidone. These ...solvents are unsustainable, repro‐toxic for humans and are therefore becoming increasingly restricted within the European Union. A new and sustainable method, aqueous phase separation (APS), is reported that eliminates the use of organic solvents. A homogeneous solution of two polyelectrolytes, the strong polyanion poly(sodium 4‐styrenesulfonate) (PSS) and the weak polycation poly(allylamine hydrochloride) (PAH), is prepared at high pH, where PAH is uncharged. Immersing a film of this solution in a low pH bath charges the PAH and results in a controlled precipitation, forming a porous water‐insoluble polyelectrolyte complex, a membrane. Pore sizes can be tuned from micrometers to just a few nanometers, and even to dense films, simply by tuning the polyelectrolyte concentrations, molecular weights, and by changing the salinity of the bath. This leads to excellent examples of microfiltration, ultrafiltration, and nanofiltration membranes. Polyelectrolyte complexation induced APS is a viable and sustainable approach to membrane production that provides excellent control over membrane properties and even allows new types of separations.
Polyelectrolyte complex membranes are prepared using an aqueous phase separation method. This method completely eliminates the use of organic solvents for membrane fabrication. Membranes with tunable pore sizes are prepared by changing the concentration of polyelectrolytes in the solution, molecular weights, and salinity of the coagulation bath. By carefully tuning these parameters, membranes for microfiltration, ultrafiltration, and nanofiltration applications can be prepared.
The gut microbiota is now considered as one of the key elements contributing to the regulation of host health. Virtually all our body sites are colonised by microbes suggesting different types of ...crosstalk with our organs. Because of the development of molecular tools and techniques (ie, metagenomic, metabolomic, lipidomic, metatranscriptomic), the complex interactions occurring between the host and the different microorganisms are progressively being deciphered. Nowadays, gut microbiota deviations are linked with many diseases including obesity, type 2 diabetes, hepatic steatosis, intestinal bowel diseases (IBDs) and several types of cancer. Thus, suggesting that various pathways involved in immunity, energy, lipid and glucose metabolism are affected.In this review, specific attention is given to provide a critical evaluation of the current understanding in this field. Numerous molecular mechanisms explaining how gut bacteria might be causally linked with the protection or the onset of diseases are discussed. We examine well-established metabolites (ie, short-chain fatty acids, bile acids, trimethylamine N-oxide) and extend this to more recently identified molecular actors (ie, endocannabinoids, bioactive lipids, phenolic-derived compounds, advanced glycation end products and enterosynes) and their specific receptors such as peroxisome proliferator-activated receptor alpha (PPARα) and gamma (PPARγ), aryl hydrocarbon receptor (AhR), and G protein-coupled receptors (ie, GPR41, GPR43, GPR119, Takeda G protein-coupled receptor 5).Altogether, understanding the complexity and the molecular aspects linking gut microbes to health will help to set the basis for novel therapies that are already being developed.
The Gut Microbiota in the First Decade of Life Derrien, Muriel; Alvarez, Anne-Sophie; de Vos, Willem M.
Trends in microbiology (Regular ed.),
December 2019, 2019-12-00, 20191201, Letnik:
27, Številka:
12
Journal Article
Recenzirano
Odprti dostop
Appreciation of the importance of the gut microbiome is growing, and it is becoming increasingly relevant to identify preventive or therapeutic solutions targeting it. The composition and function of ...the gut microbiota are relatively well described for infants (less than 3 years) and adults, but have been largely overlooked in pre-school (3–6 years) and primary school-age (6–12 years) children, as well as teenagers (12–18 years). Early reports suggested that the infant microbiota would attain an adult-like structure at the age of 3 years, but recent studies have suggested that microbiota development may take longer. This development time is of key importance because there is evidence to suggest that deviations in this development may have consequences in later life. In this review, we provide an overview of current knowledge concerning the gut microbiota, its evolution, variation, and response to dietary challenges during the first decade of life with a focus on healthy pre-school and primary school-age children (up to 12 years) from various populations around the globe. This knowledge should facilitate the identification of diet-based approaches targeting individuals of this age group, to promote the development of a healthy microbiota in later life.
The gut microbiota of healthy children displays functional and taxonomic differences with respect to those of adults, suggesting that the gut microbiome may develop more slowly than previously thought.Bifidobacterium spp. are more abundant in the gut microbiota of children than in that of adults, and may gradually decrease until adulthood.The microbiota may develop more slowly in some children than in others, who may present an intermediate microbiota state.Childhood may provide additional opportunities for microbiota-based interventions to promote health or prevent microbiota deviation.The gut microbiota of children may be more malleable to environmental factors than that of adults.Differences in lifestyle, and westernization in particular, strongly influence the composition of gut microbial populations in children, as already reported for adults.
Gut barrier function is key in maintaining a balanced response between the host and its microbiome. The microbiota can modulate changes in gut barrier as well as metabolic and inflammatory responses. ...This highly complex system involves numerous microbiota-derived factors. The gut symbiont Akkermansia muciniphila is positively correlated with a lean phenotype, reduced body weight gain, amelioration of metabolic responses and restoration of gut barrier function by modulation of mucus layer thickness. However, the molecular mechanisms behind its metabolic and immunological regulatory properties are unexplored. Herein, we identify a highly abundant outer membrane pili-like protein of A. muciniphila MucT that is directly involved in immune regulation and enhancement of trans-epithelial resistance. The purified Amuc_1100 protein and enrichments containing all its associated proteins induced production of specific cytokines through activation of Toll-like receptor (TLR) 2 and TLR4. This mainly leads to high levels of IL-10 similar to those induced by the other beneficial immune suppressive microorganisms such as Faecalibacterium prausnitzii A2-165 and Lactobacillus plantarum WCFS1. Together these results indicate that outer membrane protein composition and particularly the newly identified highly abundant pili-like protein Amuc_1100 of A. muciniphila are involved in host immunological homeostasis at the gut mucosa, and improvement of gut barrier function.
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