Gamma aminobutyric acid (GABA) is the principal inhibitory neurotransmitter playing a key role in anxiety and depression disorders in mammals. Recent studies revealed that members of the gut ...microbiota are able to produce GABA modulating the gut-brain axis response. Among members of the human gut microbiota, bifidobacteria are well known to establish many metabolic and physiologic interactions with the host. In this study, we performed genome analyses of more than 1,000 bifidobacterial strains publicly available revealing that Bifidobacterium adolescentis taxon might represent a model GABA producer in human gastrointestinal tract. Moreover, the in silico screening of human/animal metagenomic datasets showed an intriguing association/correlation between B. adolescentis load and mental disorders such as depression and anxiety. Interestingly, in vitro screening of 82 B. adolescentis strains allowed identifying two high GABA producers, i.e. B. adolescentis PRL2019 and B. adolescentis HD17T2H, which were employed in an in vivo trial in rats. Feeding Groningen rats with a supplementation of B. adolescentis strains, confirmed the ability of these microorganisms to stimulate the in vivo production of GABA highlighting their potential implication in gut-brain axis interactions.
Bifidobacteria represent one of the first colonizers of the mammalian gut, where such colonization is facilitated by their saccharolytic capabilities. Genomic analyses of bifidobacteria have revealed ...intriguing genetic strategies employed by these bacteria to access a variety of dietary and host-produced glycans. Bifidobacterial genome evolution therefore represents a fascinating example of how their chromosomes were molded to contain a large number of genes involved in carbohydrate metabolism. One of the reasons as to why bifidobacteria are such dominant and prevalent members of the (early) microbiota is that they may access glycans in the gut through mutualistic cross-feeding or resource-sharing activities, which is indicative of ‘social behavior’ among bifidobacterial strains.
Bifidobacteria represent key members of the gut microbiota in the early phases of life of animals that subject their offspring to parental care.
The first microbiota assemblage is believed to play pivotal roles in human health, both in infancy and at later stages of life.
Dietary and/or host-derived glycans represent a potent evolutionary force that has shaped the bifidobacterial pan-genome.
In silico and functional genomic analyses of bifidobacterial genomes revealed species-specific adaptation to a glycan-rich gut environment.
A key determinant of microbial dynamics in the gut microbiota results from nutrient competition and sharing.
Bifidobacteria play an important ecological role in shaping the gut microbiome.
Bifidobacteria exhibit social behavior through carbohydrate resource sharing in the gut.
The human gut microbiota is engaged in multiple interactions affecting host health during the host's entire life span. Microbes colonize the neonatal gut immediately following birth. The ...establishment and interactive development of this early gut microbiota are believed to be (at least partially) driven and modulated by specific compounds present in human milk. It has been shown that certain genomes of infant gut commensals, in particular those of bifidobacterial species, are genetically adapted to utilize specific glycans of this human secretory fluid, thus representing a very intriguing example of host-microbe coevolution, where both partners are believed to benefit. In recent years, various metagenomic studies have tried to dissect the composition and functionality of the infant gut microbiome and to explore the distribution across the different ecological niches of the infant gut biogeography of the corresponding microbial consortia, including those corresponding to bacteria and viruses, in healthy and ill subjects. Such analyses have linked certain features of the microbiota/microbiome, such as reduced diversity or aberrant composition, to intestinal illnesses in infants or disease states that are manifested at later stages of life, including asthma, inflammatory bowel disease, and metabolic disorders. Thus, a growing number of studies have reported on how the early human gut microbiota composition/development may affect risk factors related to adult health conditions. This concept has fueled the development of strategies to shape the infant microbiota composition based on various functional food products. In this review, we describe the infant microbiota, the mechanisms that drive its establishment and composition, and how microbial consortia may be molded by natural or artificial interventions. Finally, we discuss the relevance of key microbial players of the infant gut microbiota, in particular bifidobacteria, with respect to their role in health and disease.
•Establishment of host–microbe interactions has facilitated co-evolution between the host and its resident intestinal microbiota.•These mutualistic relationships are particularly important for ...developmental processes of the host during early life.•Members of the infant gut microbiota establish microbe-microbe interactions such as syntrophy or cross-feeding behavior.•Bifidobacteria are key members of the infant gut microbiota that possess adaptative traits suited to the intestinal ecological niche.•Host-microorganism interactions are mediated by a variety of molecular mechanisms that benefit both.
Current scientific literature has identified the infant gut microbiota as a multifaceted organ influencing a range of aspects of host-health and development. Many scientific studies have focused on characterizing the main microbial taxa that constitute the resident bacterial population of the infant gut. This has generated a wealth of information on the bacterial composition of the infant gut microbiota, and on the functional role/s exerted by their key microbial members. In this context, one of the most prevalent, abundant and investigated microbial taxon in the human infant gut is the genus Bifidobacterium, due to the purported beneficial activities is bestows upon its host. This review discusses the most recent findings regarding the infant gut microbiota with a particular focus on the molecular mechanisms by which bifidobacteria impact on host health and well-being.
Members of the genus
Bifidobacterium are high G
+
C Gram positive bacteria belonging to the phylum
Actinobacteria, and represent common inhabitants of the gastro-intestinal tract (GIT) of mammals, ...birds and certain cold-blooded animals. The overall microbial population that resides in the GIT, referred to as the “gut microbiota”, is an extremely complex community of microorganisms whose functions are believed to have a significant impact on human physiology. Different ecological relationships between bifidobacteria and their host can be developed, ranging from opportunistic pathogenic interactions (e.g. in the case of
Bifidobacterium dentium) to a commensal or even health-promoting relationship (e.g. in the case of
Bifidobacterium bifidum and
Bifidobacterium breve species). Among the known health-promoting or probiotic microorganisms, bifidobacteria represent one of the most dominant group and some bifidobacterial species are frequently used as the probiotic ingredient in many functional foods. However, despite the generally accepted importance of bifidobacteria as constituents of the human microbiota, there is only limited information available on their phylogeny, physiology and genetics. Moreover, host–microbiota interactions and cross-talk between different members of the gut microbiota are far from completely understood although they represent a crucial factor in the development and maintenance of human physiology and immune system. The aim of this review is to highlight the genetic and functional features of bifidobacteria residing in the human GIT using genomic and ecology-based information.
► We provide the current state of the art about biology of the genus
Bifidobacterium. ► Bifidobacteria are common inhabitants of the gastro-intestinal tracts of mammalians. ► Bifidobacteria are considered health promoting bacteria. ► Very little is known about the molecular basis of their health promoting activities. ► Probiogenomics is aimed to explore the functionality of probiotic bacteria.
The acquisition and development of the infant microbiome are key to establishing a healthy host-microbiome symbiosis. The maternal microbial reservoir is thought to play a crucial role in this ...process. However, the source and transmission routes of the infant pioneering microbes are poorly understood. To address this, we longitudinally sampled the microbiome of 25 mother-infant pairs across multiple body sites from birth up to 4 months postpartum. Strain-level metagenomic profiling showed a rapid influx of microbes at birth followed by strong selection during the first few days of life. Maternal skin and vaginal strains colonize only transiently, and the infant continues to acquire microbes from distinct maternal sources after birth. Maternal gut strains proved more persistent in the infant gut and ecologically better adapted than those acquired from other sources. Together, these data describe the mother-to-infant microbiome transmission routes that are integral in the development of the infant microbiome.
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•Strain-resolved metagenomics was used to track mother-to-infant microbiome transfer•Microbial strains from multiple maternal body sites transfer to the infant microbiome•The early microbial diversity in the infant gut is rapidly shaped by niche selection•The maternal gut microbiome is the source of the majority of transmitted strains
Ferretti et al. use metagenomics with strain-resolved computational profiling to characterize the transfer of microbes from mothers to their infants during their first 4 months of life. Multiple maternal body sites contribute to the developing infant microbiome, with maternal gut strains providing the largest contribution of colonizing microorganisms.
Bifidobacteria represent one of the dominant microbial groups that occur in the gut of various animals, being particularly prevalent during the suckling period of humans and other mammals. Their ...ability to compete with other gut bacteria is largely attributed to their saccharolytic features. Comparative and functional genomic as well as transcriptomic analyses have revealed the genetic background that underpins the overall saccharolytic phenotype for each of the 47 bifidobacterial (sub)species representing the genus Bifidobacterium, while also generating insightful information regarding carbohydrate resource sharing and cross-feeding among bifidobacteria. The abundance of bifidobacterial saccharolytic features in human microbiomes supports the notion that metabolic accessibility to dietary and/or host-derived glycans is a potent evolutionary force that has shaped the bifidobacterial genome.
Stress Physiology of Lactic Acid Bacteria Papadimitriou, Konstantinos; Alegría, Ángel; Bron, Peter A ...
Microbiology and molecular biology reviews,
09/2016, Volume:
80, Issue:
3
Journal Article
Peer reviewed
Open access
Lactic acid bacteria (LAB) are important starter, commensal, or pathogenic microorganisms. The stress physiology of LAB has been studied in depth for over 2 decades, fueled mostly by the ...technological implications of LAB robustness in the food industry. Survival of probiotic LAB in the host and the potential relatedness of LAB virulence to their stress resilience have intensified interest in the field. Thus, a wealth of information concerning stress responses exists today for strains as diverse as starter (e.g., Lactococcus lactis), probiotic (e.g., several Lactobacillus spp.), and pathogenic (e.g., Enterococcus and Streptococcus spp.) LAB. Here we present the state of the art for LAB stress behavior. We describe the multitude of stresses that LAB are confronted with, and we present the experimental context used to study the stress responses of LAB, focusing on adaptation, habituation, and cross-protection as well as on self-induced multistress resistance in stationary phase, biofilms, and dormancy. We also consider stress responses at the population and single-cell levels. Subsequently, we concentrate on the stress defense mechanisms that have been reported to date, grouping them according to their direct participation in preserving cell energy, defending macromolecules, and protecting the cell envelope. Stress-induced responses of probiotic LAB and commensal/pathogenic LAB are highlighted separately due to the complexity of the peculiar multistress conditions to which these bacteria are subjected in their hosts. Induction of prophages under environmental stresses is then discussed. Finally, we present systems-based strategies to characterize the "stressome" of LAB and to engineer new food-related and probiotic LAB with improved stress tolerance.
The human intestine retains a complex microbial ecosystem, which performs crucial functions that impact on host health. Several studies have indicated that intestinal dysbiosis may impact on the ...establishment of life-threatening intestinal diseases such as colorectal cancer. An adenomatous polyp is the result of abnormal tissue growth, which is benign but is considered to be associated with a high risk of developing colorectal cancer, based on its grade of dysplasia. Development of diagnostic tools that are based on surveying the gut microbiota and are aimed at early detection of colorectal cancer represent highly desirable target. For this purpose, we performed a pilot study in which we applied a metataxonomic analysis based on 16S rRNA gene sequencing approach to unveil the composition of microbial communities of intestinal polyps. Moreover, we performed a meta-analysis involving the reconstructed microbiota composition of adenomatous polyps and publicly available metagenomics datasets of colorectal cancer. These analyses allowed the identification of microbial taxa such as Faecalibacterium, Bacteroides and Romboutsia, which appear to be depleted in cancerogenic mucosa as well as in adenomatous polyps, thus representing novel microbial biomarkers associated with early tumor formation. Furthermore, an absolute quantification of Fusubacterium nucleatum in polyps further compounded the important role of this microorganism as a valuable putative microbial biomarker for early diagnosis of colorectal cancer.
Summary
Metagenomic studies of the human gut microbiome have only recently begun to explore the differences in taxonomic composition between subjects from diverse geographical origins. Here, we ...compared taxonomy, resistome and functional metabolic properties of publicly available shotgun datasets of human fecal samples collected from different geographical regions (Europe, North America, Asia and Oceania). Such datasets encompassed gut microbiota information corresponding to 13 developed/industrialized societies, as well as two traditional hunter‐gatherer, pre‐agricultural communities (Tanzanian and Peruvian individuals). Assessment of the retrieved taxonomic profiles allowed the most updated reconstruction of the global core‐microbiome as based on currently available data, as well as the identification and targeted genome reconstruction of bacterial taxa that appear to have been lost and/or acquired during urbanization/industrialization. Functional characterization of these metagenomic datasets indicates that the urbanization/industrialization process which occurred in recent human history has shaped the gut microbiota through the acquisition and/or loss of specific gut microbes, thereby potentially impacting on the overall functionality of the gut microbiome.
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