Stable Gut Research Articles

Gut microbiomes are largely unchanged when exposed to their amphibian host's latitudinally variable upper thermal limit.

Climate change will increase the frequency and severity of temperature extremes. Links between host thermal physiology and their gut microbiota suggest that organisms' responses to future climates may be mediated by their microbiomes, raising the question of how the thermal environment influences the microbiome itself. Vertebrate gut microbiomes influence the physiological plasticity of their hosts via effects on immunity, metabolism, and nutrient uptake. The gut microbiota of ectothermic vertebrates in particular are responsive to long-term, sub-lethal gradual increases in environmental temperature. Whether and how the gut microbiota respond to brief exposure to temperatures at the upper limit of host physiological tolerance (CTmax) is poorly understood but could have downstream effects on host fitness. We assayed the CTmax of wood frogs (Lithobates sylvaticus) from 15 populations across a 10° latitudinal gradient. We then characterized the gut microbiota of juveniles at two time points following exposure to CTmax. Frogs from higher latitudes had lower thermal tolerance (lower CTmax) than those from lower latitudes. Unexpectedly, exposure to upper survivable temperature had little to no detectable effect on the frogs' microbiota richness, stability, or composition. Instead, we found a strong effect of time in which frogs kept in recovery conditions for four days had less diverse, but more stable gut microbiota than those that had recovered for only one day, regardless of CTmax exposure. We conclude that while wood frogs from higher latitudes have reduced thermal tolerances than those from lower latitudes, their microbial communities are largely unaffected by brief exposure to high temperatures at the edge of their physiological limits.

Vaccine protection of broilers against various doses of wild-type Salmonella Typhimurium and changes in gut microbiota.

This study evaluated the impact of vaccine diluents (peptone or water) on the protective effects of Salmonella Typhimurium (S. Typhimurium) vaccine. Vaccinated broilers were challenged with different doses of wild-type S. Typhimurium through dust. At the time of cull, vaccine load was highest in caeca and lowest in spleen. Wild-type S. Typhimurium was detectable after 24 hrs only in the vaccinated birds challenged with 108 CFU and positive control. S. Typhimurium load was lower in the organs of the groups challenged with 104 and 106 compared to the 108 CFU group. The caecal microbiota alpha diversity of the vaccinated or vaccinated and challenged chickens differed from the positive and negative control groups. Beta diversity of the positive control clustered separately from all other treatment groups, showing that vaccine caused minimal changes in gut microbiota structure. The vaccinated and/or wild-type challenged chickens showed significantly higher abundance of Anaerostignum, Lachnoclostridium, Intestinimonas, Colidextribacter, Monoglobus, Acetanaerobacterium and Subdoligranulum. Outcomes from this study demonstrate that the vaccine effectively protected broiler chickens from S. Typhimurium infection and helped maintain a more stable gut microbiota structure, reducing the impact of S. Typhimurium on gut health. Vaccine diluent did not affect gut microbiota composition.

Modulatory effects of in ovo delivery of galactooligosaccharide and Lactiplantibacillus plantarum on antioxidant capacity, gene expression, and selected plasma metabolite parameters of broiler chickens.

A stable gut microbiota promotes a healthy gut and enhances immune function, antioxidant status, and metabolic activities in chickens. The present research work aimed to investigate the modulatory impacts of in ovo delivery of prebiotic and probiotic on oxidative stress, the intestinal transcriptome, and various plasma metabolites in chickens. Fertilized Ross 308 eggs were administered in ovo either with galactooligosaccharide (GOS) (3.5mg/egg or Lactiplantibacillus plantarum (LP) 1 × 106/egg on the 12th day of egg incubation. Three hundred viable Ross 308 broiler hatching eggs in total were randomly assigned to four groups, namely, the negative control not injected group, the group receiving physiological saline injections as the positive control, GOS, and LP. The analysis of genes associated with immune functions, antioxidants, barrier functions, and free fatty acid receptors were determined via qPCR. The analysis of the selected plasma blood metabolites was performed automatically with Pentra C 400. The antioxidant capacity of the chickens' liver, breast muscle, and spleen was enhanced by the in ovo injection of GOS and LP. The immune-related gene expression levels were upregulated after in ovo stimulation with either GOS or LP which improved the gut health of broiler chickens. In addition, several genes related to gut barrier functions were upregulated, thus ensuring epithelial integrity. As for blood plasma metabolites, no adverse effects were observed. In summary, we report that in ovo stimulation with either GOS or LP stimulates the immune system and improves the antioxidant status and gut health of chickens with no negative impact on plasma blood metabolite indices.

Rurality and relative poverty drive acquisition of a stable and diverse gut microbiome in early childhood in a non-industrialized setting.

There are limited longitudinal data from non-industrialized settings on patterns and determinants of gut bacterial microbiota development in early childhood. We analysed epidemiological data and stool samples collected from 60 children followed from early infancy to 5 years of age in a rural tropical district in coastal Ecuador. Data were collected longitudinally on a wide variety of individual, maternal, and household exposures. Extracted DNA from stool samples were analyzed for bacterial microbiota using 16S rRNA gene sequencing. Both alpha and beta diversity indices suggested stable profiles towards 5 years of age. Greater alpha diversity and lower beta diversity were associated with factors typical of rural poverty including low household incomes, overcrowding, and greater agricultural and animal exposures, but not with birth mode or antibiotic exposures. Consumption of unpasteurized milk was consistently associated with greater alpha diversity indices. Infants living in a non-industrialized setting in conditions of greater poverty and typically rural exposures appeared to acquire more rapidly a stable and diverse gut bacterial microbiome during childhood.

Lifestyle and the Gut-Brain Axis Insights into Mental Health and Microbiome Interactions

Introduction: The intricate relationship between lifestyle factors and gut health has become a focus of recent research, emphasizing the significant role of the gut-brain axis (GBA) in regulating both physical and emotional well- being. Unhealthy lifestyle choices, including a diet high in ultra-processed foods, irregular sleep patterns, physical inactivity, and substance abuse, have been closely associated with gut dysbiosis, leading to gastrointestinal (GI) symptoms and mood disturbances such as anxiety and depression. The gut microbiota, through the production of neurotransmitters like serotonin and dopamine, as well as short-chain fatty acids (SCFAs), influences mood and mental health via the GBA. Maintaining a healthy lifestyle, characterized by balanced nutrition, regular physical activity, and good sleep quality, is critical in fostering a diverse and stable gut microbiome, which in turn supports emotional stability.  Aim: This review aims to examine the existing literature on the impact of lifestyle factors, such as diet, physical activity, sleep, smoking, alcohol consumption, and stress management, on gut health and emotional well-being. The goal is to highlight the importance of gut microbiota in mental health and the potential therapeutic strategies to enhance gut health for improved emotional outcomes.  Methodology: A comprehensive search of peer-reviewed journal articles was conducted using databases such as PubMed, Google Scholar, and Web of Science. Keywords like "lifestyle," "gut health," "emotional well-being," "dietary habits," "physical activity," "sleep patterns," and "gut-brain axis" were used to identify relevant studies. Inclusion criteria focused on human clinical trials and observational studies published within the last 16 years. Studies involving animal subjects, non-peer- reviewed articles, and outdated research were excluded.  Results: The literature shows that diets high in fiber and low in processed foods support a healthier gut microbiome, while high consumption of ultra-processed foods disrupts gut bacteria, leading to GI symptoms and mood disorders. Regular physical activity was found to enhance gut microbiota diversity, contributing to better emotional well-being. Conversely, poor sleep quality and chronic stress were linked to gut dysbiosis, which exacerbated mood disturbances. Smoking and excessive alcohol consumption further damaged gut health, contributing to mood dysregulation. Probiotic and prebiotic interventions, particularly synbiotics, were found to restore gut balance and improve both GI and mental health outcomes.  Conclusion: This review underscores the pivotal role of lifestyle choices in shaping gut health and emotional well-being. A balanced diet, regular exercise, sufficient sleep, and stress management are essential for maintaining a healthy gut microbiome, which, in turn, supports emotional stability. Therapeutic strategies involving prebiotics, probiotics, and synbiotics offer promising avenues for improving both gut health and mood. Addressing lifestyle factors and promoting gut health can potentially serve as an effective approach for enhancing overall well-being and preventing mood disorders.

Innovative way for treating depression: The potential effects and mechanism of probiotics in coping with MDD

Abstract. Depression is a multifaceted psychiatric condition affecting more than 280 million individuals globally across diverse age brackets, constituting 12.3% of the worldwide disease burden. Among the varied manifestations, Major Depressive Disorder (MDD) stands out as a prevalent and severe form of psychopathology. The origins of depression, while not fully elucidated, are generally attributed to the intricate interplay of environmental, societal, and individual factors. Recent preclinical and clinical investigations have posited a potential association between dysbiosis, characterized by alterations in gut microbiota composition and function, and the initiation and progression of depression. Nevertheless, the precise mechanisms remain unclear, and the gut microbiota has not been a primary focal point in depression therapeutic strategies. This review outlines conceivable mechanisms linking dysbiosis in the gut microbiota to the development of depression, elucidating the intricate relationship between dysbiosis and depressive conditions. Additionally, it explores the interplay between pharmacological interventions and the gut microbiota in the context of antidepressant therapy. Simultaneously, the article investigates the potential and merits of probiotics and prebiotics as tools to modulate gut microbiota and maintain a stable gut microenvironment, positioning them as innovative agents in antidepressant therapy. This perspective introduces a novel trajectory for future research and clinical approaches in depression, underscoring the significance of preserving gut microbiota equilibrium as a promising avenue for intervention.

The symbiont Acinetobacter baumannii enhances the insect host resistance to entomopathogenic fungus Metarhizium anisopliae

Major symbiotic organisms have evolved to establish beneficial relationships with hosts. However, understanding the interactions between symbionts and insect hosts, particularly for their roles in defense against pathogens, is still limited. In a previous study, we proposed that the fungus Metarhizium anisopliae can infect the brown planthopper Nilaparvata lugens, a harmful pest for rice crops. To expand on this, we investigated changes in N. lugens’ intestinal commensal community after M. anisopliae infection and identified key gut microbiotas involved. Our results showed significant alterations in gut microbiota abundance and composition at different time points following infection with M. anisopliae. Notably, certain symbionts, like Acinetobacter baumannii, exhibited significant variations in response to the fungal infection. The decrease in these symbionts had a considerable impact on the insect host’s survival. Interestingly, reintroducing A. baumannii enhanced the host’s resistance to M. anisopliae, emphasizing its role in pathogen defense. Additionally, A. baumannii stimulated host immune responses, as evidenced by increased expression of immune genes after reintroduction. Overall, our findings highlight the significance of preserving a stable gut microbial community for the survival of insects. In specific conditions, the symbiotic microorganism A. baumannii can enhance the host’s ability to resist entomopathogenic pathogens through immune regulation.

Purified fibers in chemically defined synthetic diets destabilize the gut microbiome of an omnivorous insect model.

The macronutrient composition of a host's diet shapes its gut microbial community, with dietary fiber in particular escaping host digestion to serve as a potent carbon source for gut microbiota. Despite widespread recognition of fiber's importance to microbiome health, nutritional research often fails to differentiate hyper-processed fibers from cell-matrix derived intrinsic fibers, limiting our understanding of how individual polysaccharides influence the gut community. We use the American cockroach (Periplaneta americana) as a model system to dissect the response of complex gut microbial communities to diet modifications that are impossible to test in traditional host models. Here, we designed synthetic diets from lab-grade, purified ingredients to identify how the cockroach microbiome responds to six different carbohydrates (chitin, methylcellulose, microcrystalline cellulose, pectin, starch, xylan) in otherwise balanced diets. We show via 16S rRNA gene profiling that these synthetic diets reduce bacterial diversity and alter the phylogenetic composition of cockroach gut microbiota in a fiber-dependent manner, regardless of the vitamin and protein content of the diet. Comparisons with cockroaches fed whole-food diets reveal that synthetic diets induce blooms in common cockroach-associated taxa and subsequently fragment previously stable microbial correlation networks. Our research leverages an unconventional microbiome model system and customizable lab-grade artificial diets to shed light on how purified polysaccharides, as opposed to nutritionally complex intrinsic fibers, exert substantial influence over a normally stable gut community.

Zebrafish (Danio rerio) behavioral phenotypes are not underscored by different gut microbiomes.

Although bold and shy behavioral phenotypes in zebrafish (Danio rerio) have been selectively bred and maintained over multiple generations, it is unclear if they are underscored by different gut microbiota. Using the microbiota-gut-brain concept, we examined the relationship between gut microbiota and the behavioral phenotypes within this model animal system to assess possible gut microbe-mediated effects on host behavior. To this end, we amplified and sequenced 16S rRNA gene amplicons from the guts of bold and shy zebrafish individuals using the Illumina Miseq platform. We did not record any significant differences in within-group microbial diversity nor between-group community composition of the two behavioral phenotypes. Interestingly, though not statistically different, we determined that the gut microbial community of the bold phenotype was dominated by Burkholderiaceae, Micropepsaceae, and Propionibacteriaceae. In contrast, the shy phenotype was dominated by Beijerinckaceae, Pirelullacaeae, Rhizobiales_Incertis_Sedis, and Rubinishaeraceae. The absence of any significant difference in gut microbiome profiles between the two phenotypes would suggest that in this species, there might exist a stable core gut microbiome, regardless of behavioral phenotypes, and possibly, a limited role for the gut microbiota in modulating this selected-for host behavior. This study characterized the gut microbiomes of distinct innate behavioral phenotypes of the zebrafish (that are not considered dysbiotic states) and did not rely on antibiotic or probiotic treatments to induce changes in behavior. Such studies are crucial to our understanding of the modulating impacts of the gut microbiome on normative animal behavior.

Cyclic Oligosaccharide-Induced Modulation of Immunoglobulin A Reactivity to Gut Bacteria Contributes to Alterations in the Bacterial Community Structure.

Immunoglobulin A (IgA) is a major gut antibody that coats commensal gut bacteria and contributes to shaping a stable gut bacterial composition. Although previous studies have shown that cyclic oligosaccharides, including cyclic nigerosyl-1,6-nigerose (CNN) and cyclodextrins (CDs, including αCD, βCD, and γCD), alter the gut bacterial composition, it remains unclear whether cyclic oligosaccharides modify the IgA coating of gut bacteria, which relates to cyclic oligosaccharide-induced alteration of the gut bacterial composition. To address this issue, mice were maintained for 12 weeks on diets containing CNN, αCD, βCD, or γCD; the animals' feces were evaluated for their bacterial composition and the IgA coating index (ICI), a measure of the degree of IgA coating of bacteria. We observed that the intake of each cyclic oligosaccharide altered the gut bacterial composition, with changes in the ICI found at both the phylum and genus levels. The ICI for Bacillota, Lachnospiraceae NK4A136 group, UC Lachnospiraceae, and Tuzzerella were significantly and positively correlated with the relative abundance (RA) in total bacteria for these bacteria; in contrast, significant correlations were not seen for other phyla and genera. Our observations suggest that cyclic oligosaccharide-induced modulation of the IgA coating of gut bacteria may partly relate to changes in the community structure of the gut bacteria.

Effect of Mutant and Engineered High-Acetate-Producing Saccharomyces cerevisiae var. boulardii Strains in Dextran Sodium Sulphate-Induced Colitis.

Acetate-producing Saccharomyces cerevisiae var. boulardii strains could exert improved effects on ulcerative colitis, which here, was preclinically evaluated in an acute dextran sodium sulphate induced model of colitis. Nine-week-old female mice were divided into 12 groups, receiving either drinking water or 2.75% dextran sodium sulphate for 7 days, combined with a daily gavage of various treatments with different levels of acetate accumulation: sham control (phosphate buffered saline, no acetate), non-probiotic control (Baker's yeast, no acetate), probiotic control (Enterol®, transient acetate), and additionally several Saccharomyces cerevisiae var. boulardii strains with respectively no, high, and extra-high acetate accumulation. Disease activity was monitored daily, and feces samples were collected at different timepoints. On day 14, the mice were sacrificed, upon which blood and colonic tissue were collected for analysis. Disease activity in inflamed mice was lower when treated with the high-acetate-producing strain compared to sham and non-probiotic controls. The non-acetate-producing strain showed higher disease activity compared to the acetate-producing strains. Accordingly, higher histologic inflammation was observed in non- or transient-acetate-producing strains compared to the sham control, whereas this increase was not observed for high- and extra-high-acetate-producing strains upon induction of inflammation. These anti-inflammatory findings were confirmed by transcriptomic analysis of differentially expressed genes. Moreover, only the strain with the highest acetate production was superior in maintaining a stable gut microbial alpha-diversity upon inflammation. These findings support new possibilities for acetate-mediated management of inflammation in inflammatory bowel disease by administrating high-acetate-producing Saccharomyces cerevisae var. boulardii strains.

Life stage and vaccination shape the gut microbiome of hatchery-reared Atlantic salmon (Salmo salar) intended for river stocking

Microbiomes play an essential role in promoting host health and fitness in fishes, but the factors driving variation in gut microbiomes among individuals are not fully recognized. Understanding the biological and environmental factors influencing variation in the gut microbiome in fishes is needed to link microbiome composition to host physiology and potentially design manipulations to improve rearing success in fisheries and aquaculture. In this study, we characterized the gut microbiomes of Atlantic salmon (Salmo salar), a globally important species in commercial aquaculture and recreational fishing, considering life stage, vaccination status, and hatchery origin. Microbiomes diverged between hatchery sub-adults (age-0 parrs) and wild adults, with sub-adults exhibiting higher diversity and more similar microbiome communities when compared to adults. The diversity and composition of gut microbiomes did not differ between groups of adults that were reared in two different hatcheries and sampled from the wild. We also found that oral vaccines against bacterial kidney disease (BKD) reduced gut microbial diversity within individual sub-adult salmon, driving increased differentiation of gut microbial communities among individuals. Unvaccinated sub-adults displayed a stable core gut microbiome that was greatly reduced upon vaccination for BKD. Our results suggest that life stage is an essential factor shaping the gut microbiome of Atlantic salmon, likely driven by differences in habitat and diet, and that BKD vaccination can lead to a rapid disruption of the gut microbiome. Conditions experienced in the hatchery environment appear to have a strong influence on host gut microbiomes, but differences at early life stages may be lost due to environmental factors experienced in the wild. The plasticity of the gut microbiome throughout the life of individuals may have important implications for understanding host health, with potential applications for improving the rearing and reintroduction success of the ecologically and economically important Atlantic salmon.

Metaproteomic portrait of the healthy human gut microbiota

Gut metaproteomics can provide direct evidence of microbial functions actively expressed in the colonic environments, contributing to clarify the role of the gut microbiota in human physiology. In this study, we re-analyzed 10 fecal metaproteomics datasets of healthy individuals from different continents and countries, with the aim of identifying stable and variable gut microbial functions and defining the contribution of specific bacterial taxa to the main metabolic pathways. The “core” metaproteome included 182 microbial functions and 83 pathways that were identified in all individuals analyzed. Several enzymes involved in glucose and pyruvate metabolism, along with glutamate dehydrogenase, acetate kinase, elongation factors G and Tu and DnaK, were the proteins with the lowest abundance variability in the cohorts under study. On the contrary, proteins involved in chemotaxis, response to stress and cell adhesion were among the most variable functions. Random-effect meta-analysis of correlation trends between taxa, functions and pathways revealed key ecological and molecular associations within the gut microbiota. The contribution of specific bacterial taxa to the main biological processes was also investigated, finding that Faecalibacterium is the most stable genus and the top contributor to anti-inflammatory butyrate production in the healthy gut microbiota. Active production of other mucosal immunomodulators facilitating host tolerance was observed, including Roseburia flagellin and lipopolysaccharide biosynthetic enzymes expressed by members of Bacteroidota. Our study provides a detailed picture of the healthy human gut microbiota, contributing to unveil its functional mechanisms and its relationship with nutrition, immunity, and environmental stressors.

Effects of removing in-feed antibiotics and zinc oxide on the taxonomy and functionality of the microbiota in post weaning pigs

BackgroundPost weaning diarrhoea (PWD) causes piglet morbidity and mortality at weaning and is a major driver for antimicrobial use worldwide. New regulations in the EU limit the use of in-feed antibiotics (Ab) and therapeutic zinc oxide (ZnO) to prevent PWD. New approaches to control PWD are needed, and understanding the role of the microbiota in this context is key. In this study, shotgun metagenome sequencing was used to describe the taxonomic and functional evolution of the faecal microbiota of the piglet during the first two weeks post weaning within three experimental groups, Ab, ZnO and no medication, on commercial farms using antimicrobials regularly in the post weaning period.ResultsDiversity was affected by day post weaning (dpw), treatment used and diarrhoea but not by the farm. Microbiota composition evolved towards the dominance of groups of species such as Prevotella spp. at day 14dpw. ZnO inhibited E. coli overgrowth, promoted higher abundance of the family Bacteroidaceae and decreased Megasphaera spp. Animals treated with Ab exhibited inconsistent taxonomic changes across time points, with an overall increase of Limosilactobacillus reuteri and Megasphaera elsdenii. Samples from non-medicated pigs showed virulence-related functions at 7dpw, and specific ETEC-related virulence factors were detected in all samples presenting diarrhoea. Differential microbiota functions of pigs treated with ZnO were related to sulphur and DNA metabolism, as well as mechanisms of antimicrobial and heavy metal resistance, whereas Ab treated animals exhibited functions related to antimicrobial resistance and virulence.ConclusionAb and particularly ZnO maintained a stable microbiota composition and functionality during the two weeks post weaning, by limiting E. coli overgrowth, and ultimately preventing microbiota dysbiosis. Future approaches to support piglet health should be able to reproduce this stable gut microbiota transition during the post weaning period, in order to maintain optimal gut physiological and productive conditions.

The Potential of Co-Evolution and Interactions of Gut Bacteria-Phages in Bamboo-Eating Pandas: Insights from Dietary Preference-Based Metagenomic Analysis.

Bacteria and phages are two of the most abundant biological entities in the gut microbiome, and diet and host phylogeny are two of the most critical factors influencing the gut microbiome. A stable gut bacterial community plays a pivotal role in the host's physiological development and immune health. A phage is a virus that directly infects bacteria, and phages' close associations and interactions with bacteria are essential for maintaining the stability of the gut bacterial community and the entire microbial ecosystem. Here, we utilized 99 published metagenomic datasets from 38 mammalian species to investigate the relationship (diversity and composition) and potential interactions between gut bacterial and phage communities and the impact of diet and phylogeny on these communities. Our results highlight the co-evolutionary potential of bacterial-phage interactions within the mammalian gut. We observed a higher alpha diversity in gut bacteria than in phages and identified positive correlations between bacterial and phage compositions. Furthermore, our study revealed the significant influence of diet and phylogeny on mammalian gut bacterial and phage communities. We discovered that the impact of dietary factors on these communities was more pronounced than that of phylogenetic factors at the order level. In contrast, phylogenetic characteristics had a more substantial influence at the family level. The similar omnivorous dietary preference and closer phylogenetic relationship (family Ursidae) may contribute to the similarity of gut bacterial and phage communities between captive giant panda populations (GPCD and GPYA) and omnivorous animals (OC; including Sun bear, brown bear, and Asian black bear). This study employed co-occurrence microbial network analysis to reveal the potential interaction patterns between bacteria and phages. Compared to other mammalian groups (carnivores, herbivores, and omnivores), the gut bacterial and phage communities of bamboo-eating species (giant pandas and red pandas) exhibited a higher level of interaction. Additionally, keystone species and modular analysis showed the potential role of phages in driving and maintaining the interaction patterns between bacteria and phages in captive giant pandas. In sum, gaining a comprehensive understanding of the interaction between the gut microbiota and phages in mammals is of great significance, which is of great value in promoting healthy and sustainable mammals and may provide valuable insights into the conservation of wildlife populations, especially endangered animal species.

Resource partitioning among endangered and non-native bitterling fishes in a small pond: insights from stable isotope and gut content analyses

Resource partitioning among endangered and non-native bitterling fishes in a small pond: insights from stable isotope and gut content analyses

The effects of food provisioning on the gut microbiota community and antibiotic resistance genes of Yunnan snub-nosed monkey.

Yunnan snub-nosed monkeys (Rhinopithecus bieti) are the highest elevation lived non-human primate, and their survival has been threatened for decades. To promote their population growth, a reserve provides a typical monkey population with supplemental food. However, the influences of this food provisioning on their gut microbiota and antibiotic resistance genes (ARGs) were unknown. Therefore, we investigated the gut microbiota and ARGs of the food-provisioned monkey population compared with another wild foraging population. We found that food provisioning significantly increased the gut microbiota diversity and changed the community composition, particularly increased both the Firmicutes abundance and Firmicutes/Bacteroidetes ratio. Meanwhile, the food provisioning decreased the complex and stable gut microbiota network. KEGG functions were also influenced by food provisioning, with wild foraging monkeys showing higher functions of metabolism and genetic information processing, especially the carbohydrate metabolism, while food-provisioned monkeys exhibited increased environmental information processing, cellular processes, and organismal systems, including valine, leucine, and isoleucine degradation. In addition, food provisioning increased the abundance of ARGs in the gut microbiota, with most increasing the abundance of bacA gene and changing the correlations between specific ARGs and bacterial phyla in each population. Our study highlights that even food provisioning could promote wildlife nutrient intake, and it is necessary to pay attention to the increased ARGs and potential effects on gut microbiota stability and functions for this human conservation measure.

The Gut Microbiome–Human Body Symbiosis: Relevance of the Ubiquitous Microbial Community on Health and Development, Part 2

The human gut microbiome, comprising a range of microbial species (~100 to 1,000), is an extremely malleable ecosystem. It originates around the time of human birth and evolves as the infant grows until it matures into the relatively stable adult gut composition. Through this dynamic evolution, the composition of the gut microbiome is influenced or altered by factors such as diet, environment, mode of birth, genetics, infections, and medications. Strong associations between such alterations (dysbiosis) and diseases have led scientists to develop therapies that target a malfunctioning gut. Research is now focused on the microbiota or their associated metabolites as potential therapies. Treatment options explored include prebiotics, probiotics, postbiotics, synbiotics, fecal microbiota transplants, and live biotherapeutic products. The gut microbiome is not a panacea for all health issues; rather, it is part of a large network of interconnected operating systems within the human body. As communicators of scientific data, medical writers play a vital role in educating the public on the merits and limitations of gut microbiome therapeutics. Popular discourse, however, can be influenced by misinformation. With the ever-growing influence of social media, the lay reader must learn how to critically appraise the health information propagated by these sources. This second part of the gut microbiome series explores the association of the gut microbiome with human disease and the role that social media plays in influencing the popular perception and understanding of the importance of the gut microbiome. Approved and experimental therapies using the gut microbiome will be discussed.

Prognostic Value of Gut Microbiome for Conversion from Mild Cognitive Impairment to Alzheimer's Disease Dementia within 4 Years: Results from the AlzBiom Study.

Alterations in the gut microbiome are associated with the pathogenesis of Alzheimer's disease (AD) and can be used as a diagnostic measure. However, longitudinal data of the gut microbiome and knowledge about its prognostic significance for the development and progression of AD are limited. The aim of the present study was to develop a reliable predictive model based on gut microbiome data for AD development. In this longitudinal study, we investigated the intestinal microbiome in 49 mild cognitive impairment (MCI) patients over a mean (SD) follow-up of 3.7 (0.6) years, using shotgun metagenomics. At the end of the 4-year follow-up (4yFU), 27 MCI patients converted to AD dementia and 22 MCI patients remained stable. The best taxonomic model for the discrimination of AD dementia converters from stable MCI patients included 24 genera, yielding an area under the receiver operating characteristic curve (AUROC) of 0.87 at BL, 0.92 at 1yFU and 0.95 at 4yFU. The best models with functional data were obtained via analyzing 25 GO (Gene Ontology) features with an AUROC of 0.87 at BL, 0.85 at 1yFU and 0.81 at 4yFU and 33 KO [Kyoto Encyclopedia of Genes and Genomes (KEGG) ortholog] features with an AUROC of 0.79 at BL, 0.88 at 1yFU and 0.82 at 4yFU. Using ensemble learning for these three models, including a clinical model with the four parameters of age, gender, body mass index (BMI) and Apolipoprotein E (ApoE) genotype, yielded an AUROC of 0.96 at BL, 0.96 at 1yFU and 0.97 at 4yFU. In conclusion, we identified novel and timely stable gut microbiome algorithms that accurately predict progression to AD dementia in individuals with MCI over a 4yFU period.

Competitive interaction in headwaters: slow upstream migration leads to trophic competition between native and non-native amphipods

The spread of non-native species is one of the outcomes of global change, threatening many native communities through predation and competition. Freshwater ecosystems are particularly affected by species turnover with non-native species. One species that has been established in Central Europe for many decades – or even a few centuries – is the amphipod crustacean Gammarus roeselii. Although G. roeselii is nowadays widespread in major river systems, there have been recent reports of its spread into smaller streams that are typically inhabited by the native species Gammarus fossarum. Due to their leaf shredding ability, G. fossarum takes up a key position in headwater streams. This raises the important question, to what extent G. roeselii can equivalently take over this function. To answer this question, we collected both species from nine different sites in a mid-mountain river system (Kinzig catchment, Hesse, Germany) and investigated their functional similarity using a combination of stable isotope analysis, gut content and functional morphology. The species hardly differed in morphological characteristics, only females showed differences in some traits. Gut content analysis indicated a broad dietary overlap, while stable isotopes showed a higher trophic position of G. roeselii. The observed functional overlap could intensify interspecific competition and allow the larger and more predaceous G. roeselii to replace G. fossarum in the future as a headwater keystone species. However, the differentiation in the stable isotopes also shows that co-existence can occur by occupying different trophic niches. Moreover, the wide range of inhabited sites and exploited resources demonstrate the omnivorous lifestyle of G. roeselii, which is likely to help the species succeed in rapidly changing environments.