How fucose of blood group glycotypes programs human gut microbiota

Formation of appropriate gut microbiota is essential for human health. The first two years of life is the critical period for this process. Selection of mutualistic microorganisms of the intestinal microbiota is controlled by the FUT2 and FUT3 genes that encode fucosyltransferases, enzymes responsible for the synthesis of fucosylated glycan structures of mucins and milk oligosaccharides. In this review, the mechanisms of the selection and maintenance of intestinal microorganisms that involve fucosylated oligosaccharides of breast milk and mucins of the newborn’s intestine are described. Possible reasons for the use of fucose, and not sialic acid, as the major biological signal for the selection are also discussed.     

The composition of the gut microbiota shapes the colon mucus barrier

Two C57BL/6 mice colonies maintained in two rooms of the same specific pathogen-free (SPF) facility were found to have different gut microbiota and a mucus phenotype that was specific for each colony. The thickness and growth of the colon mucus were similar in the two colonies. However, one colony had mucus that was impenetrable to bacteria or beads the size of bacteria—which is comparable to what we observed in free-living wild mice—whereas the other colony had an inner mucus layer penetrable to bacteria and beads. The different properties of the mucus depended on the microbiota, as they were transmissible by transfer of caecal microbiota to germ-free mice. Mice with an impenetrable mucus layer had increased amounts of Erysipelotrichi, whereas mice with a penetrable mucus layer had higher levels of Proteobacteria and TM7 bacteria in the distal colon mucus. Thus, our study shows that bacteria and their community structure affect mucus barrier properties in ways that can have implications for health and disease. It also highlights that genetically identical animals housed in the same facility can have rather distinct microbiotas and barrier structures.     

肠道菌群代谢作用与人体健康关系的研究进展

人体肠道内寄居的大量共生微生物可以通过多方面作用影响人体健康,特别是肠道内菌群的代谢作用,及与人体自身代谢的交互作用在人类的健康促进与疾病的发生、发展中起着重要作用。本文从正反两面讨论了肠道菌群代谢作用对人体健康的影响,并进一步探讨了肠道菌群代谢在健康监测、疾病的预防与治疗,以及个体化医疗方面的运用。     

肠道菌群与代谢研究进展

从出生伊始肠道菌群就依赖于宿主的基因组、营养和生活方式而变化的,与宿主共同进化发展.肠道菌群参与调控其宿主的多种代谢途径,包括宿主的免疫、营养,并且极大地影响宿主的物质能量代谢及与物质能量代谢相关疾病的发生与发展过程.同时又与多个器官共同作用,在宿主的代谢、信息传递,疾病的感染与防御方面起非常重要的作用.深入了解肠道菌群在其参与代谢的具体作用,对理解物质能量代谢相关疾病病因、优化治疗策略、调节肠道菌群、防治疾病和提高宿主健康水平具有重要作用.本研究对人类肠道菌群的形成、物质能量代谢、代谢相关疾病及其防治等方面的研究进展加以综述.     

Flavonoid metabolism: the interaction of metabolites and gut microbiota

Abstract

Several dietary flavonoids exhibit anti-oxidative, anti-inflammatory, and anti-osteoporotic activities relevant to prevention of chronic diseases, including lifestyle-related diseases. Dietary flavonoids (glycoside forms) are enzymatically hydrolyzed and absorbed in the intestine, and are conjugated to their glucuronide/sulfate forms by phase II enzymes in epithelial cells and the liver. The intestinal microbiota plays an important role in the metabolism of flavonoids found in foods. Some specific products of bacterial transformation, such as ring-fission products and reduced metabolites, exhibit enhanced properties. Studies on the metabolism of flavonoids by the intestinal microbiota are crucial for understanding the role of these compounds and their impact on our health. This review focused on the metabolic pathways, bioavailability, and physiological role of flavonoids, especially metabolites of quercetin and isoflavone produced by the intestinal microbiota.     

Accessing the mobile metagenome of the human gut microbiota

This article outlines current and possible future strategies to access the mobile metagenome of bacterial ecosystems. Evidence for the role of this genetic resource in development and maintenance of core community functions of the human gut microbiota is reviewed.     

Proteomics,human gut microbiota and probiotics

The various bacterial communities associated with humans have many functions and the gut microbiota has a major role in the host. Bacterial imbalance in the gut, known as dysbiosis, has therefore been linked to several diseases. Probiotics, that is, microbial strains that have beneficial effects on the host, are thought to benefit this intestinal ecosystem. Hence, knowledge of the gut microbiota composition and an understanding of its functionalities are of interest. Recently, efforts have focused on developing new high-throughput techniques for studying microbial cells and complex communities. Among them, proteomics is increasingly being used. The purpose of this article is to focus on the recent development of this technology and its usefulness in analyzing the human gut ecosystem and probiotic strains.     

Proteomics, human gut microbiota and probiotics

The various bacterial communities associated with humans have many functions and the gut microbiota has a major role in the host. Bacterial imbalance in the gut, known as dysbiosis, has therefore been linked to several diseases. Probiotics, that is, microbial strains that have beneficial effects on the host, are thought to benefit this intestinal ecosystem. Hence, knowledge of the gut microbiota composition and an understanding of its functionalities are of interest. Recently, efforts have focused on developing new high-throughput techniques for studying microbial cells and complex communities. Among them, proteomics is increasingly being used. The purpose of this article is to focus on the recent development of this technology and its usefulness in analyzing the human gut ecosystem and probiotic strains.     

Genetic modification of iron metabolism in mice affects the gut microbiota

The composition of the gut microbiota is affected by environmental factors as well as host genetics. Iron is one of the important elements essential for bacterial growth, thus we hypothesized that changes in host iron homeostasis, may affect the luminal iron content of the gut and thereby the composition of intestinal bacteria. The iron regulatory protein 2 (Irp2) and one of the genes mutated in hereditary hemochromatosis Hfe , are both proteins involved in the regulation of systemic iron homeostasis. To test our hypothesis, fecal metal content and a selected spectrum of the fecal microbiota were analyzed from Hfe-/-, Irp2-/- and their wild type control mice. Elevated levels of iron as well as other minerals in feces of Irp2-/- mice compared to wild type and Hfe-/- mice were observed. Interestingly significant variation in the general fecal-bacterial population-patterns was observed between Irp2-/- and Hfe-/- mice. Furthermore the relative abundance of five species, mainly lactic acid bacteria, was significantly different among the mouse lines. Lactobacillus (L.) murinus and L. intestinalis were highly abundant in Irp2-/- mice, Enterococcus faecium species cluster and a species most similar to Olsenella were highly abundant in Hfe-/- mice and L. johnsonii was highly abundant in the wild type mice. These results suggest that deletion of iron metabolism genes in the mouse host affects the composition of its intestinal bacteria. Further studying the relationship between gut microbiota and genetic mutations affecting systemic iron metabolism in human should lead to clinical implications.     

How mass spectrometric approaches applied to bacterial identification have revolutionized the study of human gut microbiota

Introduction: Describing the human hut gut microbiota is one the most exciting challenges of the 21^st century. Currently, high-throughput sequencing methods are considered as the gold standard for this purpose, however, they suffer from several drawbacks, including their inability to detect minority populations. The advent of mass-spectrometric (MS) approaches to identify cultured bacteria in clinical microbiology enabled the creation of the culturomics approach, which aims to establish a comprehensive repertoire of cultured prokaryotes from human specimens using extensive culture conditions.

Areas covered: This review first underlines how mass spectrometric approaches have revolutionized clinical microbiology. It then highlights the contribution of MS-based methods to culturomics studies, paying particular attention to the extension of the human gut microbiota repertoire through the discovery of new bacterial species.

Expert commentary: MS-based approaches have enabled cultivation methods to be resuscitated to study the human gut microbiota and thus to fill in the blanks left by high-throughput sequencing methods in terms of culturing minority populations. Continued efforts to recover new taxa using culture methods, combined with their rapid implementation in genomic databases, would allow for an exhaustive analysis of the gut microbiota through the use of a comprehensive approach.     

肠道细菌微生态与人类疾病关系研究进展

寄居在人类肠道的数以亿计的肠道细菌,已被证实与人类多种疾病有关。就肠道细菌与内分泌系统疾病、消化系统疾病、心血管系统疾病、神经系统疾病、获得性免疫缺陷综合征以及特应性疾病等的关系研究进展进行综述。     

Comparative analysis of human gut microbiota by barcoded pyrosequencing

Humans host complex microbial communities believed to contribute to health maintenance and, when in imbalance, to the development of diseases. Determining the microbial composition in patients and healthy controls may thus provide novel therapeutic targets. For this purpose, high-throughput, cost-effective methods for microbiota characterization are needed. We have employed 454-pyrosequencing of a hyper-variable region of the 16S rRNA gene in combination with sample-specific barcode sequences which enables parallel in-depth analysis of hundreds of samples with limited sample processing. In silico modeling demonstrated that the method correctly describes microbial communities down to phylotypes below the genus level. Here we applied the technique to analyze microbial communities in throat, stomach and fecal samples. Our results demonstrate the applicability of barcoded pyrosequencing as a high-throughput method for comparative microbial ecology.     

Beneficial modulation of the gut microbiota

The human gut microbiota comprises approximately 100 trillion microbial cells and has a significant effect on many aspects of human physiology including metabolism, nutrient absorption and immune function. Disruption of this population has been implicated in many conditions and diseases, including examples such as obesity, inflammatory bowel disease and colorectal cancer that are highlighted in this review. A logical extension of these observations suggests that the manipulation of the gut microbiota can be employed to prevent or treat these conditions. Thus, here we highlight a variety of options, including the use of changes in diet (including the use of prebiotics), antimicrobial-based intervention, probiotics and faecal microbiota transplantation, and discuss their relative merits with respect to modulating the intestinal community in a beneficial way.