Composition Of Human Microbiota Research Articles

Modulation of human gut microbiota by linear and branched fructooligosaccharides in an in vitro colon model (TIM-2).

This study aimed to compare the effects of linear and branched fructooligosaccharides (FOS) extracted from chicory and grass (Lolium perenne), respectively on human microbiota composition, diversity, and metabolism. To test the effects of linear and branched FOS on human microbiota we used the artificial in vitro human colon model (TIM-2). Microbiota composition and diversity were assessed by V3-V4 16S rRNA metagenomic sequencing, followed by differential taxa abundance and alpha/beta diversity analyses. SCFA/BCFA production was evaluated by gas chromatography-mass spectrometry. As a result, branched FOS had the most beneficial effects on microbial diversity and metabolite production. Also, branched FOS significantly increased the abundance of commensal bacteria associated with maintaining healthy gut functions and controlling inflammation, such as Butyricicoccus, Erysipelotrichaceae, Phascolarctobacterium, and Sutterella. Linear FOS also significantly increased the abundance of some other commensal gut bacteria (Anaerobutyricum, Lachnospiraceae, Faecalibacterium), but there were no differences in diversity metrics compared to the control. The study revealed that branched FOS had the most beneficial effects compared to the linear FOS in vitro, concerning microbiota modulation, and metabolite production, making this a good candidate for further studies in food biotechnology.

Effects of Limosilactobacillus reuteri ID-D01 Probiotic Supplementation on Exercise Performance and Gut Microbiota in Sprague-Dawley Rats.

The gut microbiota composition in animals and humans has recently been found to be influenced by exercise. Although Limosilactobacillus reuteri strains have notable probiotic properties that promote human health, understanding of its effects in combination with exercise and physical activity is limited. Therefore, this study examined the effects of L. reuteri ID-D01, a human-derived probiotic, on exercise performance and fatigue in Sprague-Dawley rats. Organ weight, maximal running distance, serum biochemistry, muscle performance, microbial community composition, and short-chain fatty acid (SCFA) levels were assessed. Results indicated that ID-D01 supplementation significantly improved endurance performance. Rats in the probiotic group demonstrated a significant increase in maximal running distance compared with that in the control group (p < 0.05). Additionally, levels of fatigue markers, such as lactate and creatine phosphokinase, were significantly reduced in the ID-D01-administered groups, suggesting its potential to alleviate exercise-induced fatigue. Microbiome analysis revealed a distinct shift in gut microbiota composition in response to ID-D01 administration. The group that received ID-D01 probiotics exhibited a significant increase in the abundance of SCFA-producing bacteria, particularly Akkermansia spp., compared with that in the control groups. Furthermore, they showed elevated production of SCFAs, such as acetate and butyrate. In conclusion, this study demonstrated that ID-D01 can enhance exercise performance and reduce fatigue. Herein, we highlighted that human-derived probiotics could improve physical performance, as observed by changes in gut microbiota composition and SCFA production.

Current progresses and challenges for microbiome research in human health: a perspective.

It is becoming increasingly clear that the human microbiota, also known as "the hidden organ", possesses a pivotal role in numerous processes involved in maintaining the physiological functions of the host, such as nutrient extraction, biosynthesis of bioactive molecules, interplay with the immune, endocrine, and nervous systems, as well as resistance to the colonization of potential invading pathogens. In the last decade, the development of metagenomic approaches based on the sequencing of the bacterial 16s rRNA gene via Next Generation Sequencing, followed by whole genome sequencing via third generation sequencing technologies, has been one of the great advances in molecular biology, allowing a better profiling of the human microbiota composition and, hence, a deeper understanding of the importance of microbiota in the etiopathogenesis of different pathologies. In this scenario, it is of the utmost importance to comprehensively characterize the human microbiota in relation to disease pathogenesis, in order to develop novel potential treatment or preventive strategies by manipulating the microbiota. Therefore, this perspective will focus on the progress, challenges, and promises of the current and future technological approaches for microbiome profiling and analysis.

Full-length 16S rRNA gene sequencing by PacBio improves taxonomic resolution in human microbiome samples

BackgroundSequencing variable regions of the 16S rRNA gene (≃300 bp) with Illumina technology is commonly used to study the composition of human microbiota. Unfortunately, short reads are unable to differentiate between highly similar species. Considering that species from the same genus can be associated with health or disease it is important to identify them at the lowest possible taxonomic rank. Third-generation sequencing platforms such as PacBio SMRT, increase read lengths allowing to sequence the whole gene with the maximum taxonomic resolution. Despite its potential, full length 16S rRNA gene sequencing is not widely used yet. The aim of the current study was to compare the sequencing output and taxonomic annotation performance of the two approaches (Illumina short read sequencing and PacBio long read sequencing of 16S rRNA gene) in different human microbiome samples. DNA from saliva, oral biofilms (subgingival plaque) and faeces of 9 volunteers was isolated. Regions V3-V4 and V1-V9 were amplified and sequenced by Illumina Miseq and by PacBio Sequel II sequencers, respectively.ResultsWith both platforms, a similar percentage of reads was assigned to the genus level (94.79% and 95.06% respectively) but with PacBio a higher proportion of reads were further assigned to the species level (55.23% vs 74.14%). Regarding overall bacterial composition, samples clustered by niche and not by sequencing platform. In addition, all genera with > 0.1% abundance were detected in both platforms for all types of samples. Although some genera such as Streptococcus tended to be observed at higher frequency in PacBio than in Illumina (20.14% vs 14.12% in saliva, 10.63% vs 6.59% in subgingival plaque biofilm samples) none of the differences were statistically significant when correcting for multiple testing.ConclusionsThe results presented in the current manuscript suggest that samples sequenced using Illumina and PacBio are mostly comparable. Considering that PacBio reads were assigned at the species level with higher accuracy than Illumina, our data support the use of PacBio technology for future microbiome studies, although a higher cost is currently required to obtain an equivalent number of reads per sample.

Yinhuang buccal tablet alters airway microbiota composition and metabolite profile in healthy humans

Ethnopharmacological relevancePerturbations in airway microbiota composition and disruption of microbe-metabolite interactions have been observed in respiratory infectious diseases (RIDs). The Yinhuang (YH) buccal tablet, as an ancient Chinese medicinal formula, has been traditionally employed for the management of upper RIDs. However, there is a lack of evidence for the effects of YH buccal tablets on upper respiratory tract microbiota and circulating metabolites. Aim of the studyThe aim of this study was to analyze the changes in respiratory microbiota composition and circulating metabolite profile after YH buccal tablets administration. Materials and methodsThroat swab samples and serum samples were collected from 60 healthy subjects for high-throughput 16S ribosomal RNA gene (16S rRNA) sequencing and non-targeted Ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis. ResultsAirway microbial composition changed significantly after YH administration. The abundance of Actinomyces and Prevotella_7 increased, while the abundance of potentially pathogenic Pseudomonas and Corynebacterium decreased. A total of 168 significant HMDB taxonomic metabolites were identified in serum samples, of which lipid metabolites accounted for the largest proportion. Correlation analysis showed that circulatory metabolites were significantly correlated with changes in airway microbiota composition. ConclusionsYH buccal tablets can inhibit opportunistic pathogens, increase beneficial microorganisms in the upper respiratory tract, and regulate the body's metabolic pathways. These findings provide insights into the mechanism of action of YH buccal tablets in the treatment and prevention of respiratory diseases.

In vitro antibacterial activity of antiretroviral drugs on key commensal bacteria from the human microbiota.

Antiretroviral therapy has improved life expectancy in HIV-infected patients. However, people living with HIV under antiretroviral therapy are at higher risks of developing chronic complications and acquiring multidrug resistant bacteria than healthy population. These factors have been associated with shifts in gut microbiome composition and immune activation. It is unclear how antiretroviral drugs affect gut microbiota composition, but it has been observed that antiretroviral treatment is not able to fully restore gut health after HIV infection. Additionally, some antiretroviral drugs have shown antibacterial activity suggesting that these drugs could have a direct impact on the human microbiome composition. We determined the in vitro antibacterial activity of 16 antiretroviral drugs against a set of key clinically relevant and human commensal bacterial strains. Our results demonstrate that 5 antiretroviral drugs have in vitro antibacterial activity against gut and vaginal human commensal bacteria. Zidovudine has antibacterial activity against Escherichia coli, Klebsiella pneumoniae and Prevotella bivia, abacavir against Gardnerella vaginalis, efavirenz against G. vaginalis and P. bivia and bictegravir against Enterococcus spp. and G. vaginalis. Moreover, we describe for the first time that elvitegravir has antibacterial activity against G. vaginalis and P. bivia and, most importantly, against vancomycin-resistant Enterococcus spp. and methicillin-resistant Staphylococcus aureus strains with MIC values of 4-16 and 4 µg/mL, respectively showing high level of effectiveness against the tested multidrug-resistant bacteria. Our results underscore that some antiretroviral drugs may influence the human microbiota composition. In addition, we report the potential use of elvitegravir to treat multidrug-resistant Gram-positive bacteria warranting the need of clinical studies to repurpose this antiretroviral drug.

AG1® Induces a Favorable Impact on Gut Microbial Structure and Functionality in the Simulator of Human Intestinal Microbial Ecosystem® Model.

Modulation of the human gut microbiome has become an area of interest in the nutraceutical space. We explored the effect of the novel foundational nutrition supplement AG1® on the composition of human microbiota in an in vitro experimental design. Employing the Simulator of Human Intestinal Microbial Ecosystem (SHIME®) model, AG1® underwent digestion, absorption, and subsequent colonic microenvironment simulation under physiologically relevant conditions in healthy human fecal inocula. Following 48 h of colonic simulation, the gut microbiota were described using shallow shotgun, whole genome sequencing. Metagenomic data were used to describe changes in community structure (alpha diversity, beta diversity, and changes in specific taxa) and community function (functional heterogeneity and changes in specific bacterial metabolic pathways). Results showed no significant change in alpha diversity, but a significant effect of treatment and donor and an interaction between the treatment and donor effect on structural heterogeneity likely stemming from the differential enrichment of eight bacterial taxa. Similar findings were observed for community functional heterogeneity likely stemming from the enrichment of 20 metabolic pathways characterized in the gene ontology term database. It is logical to conclude that an acute dose of AG1 has significant effects on gut microbial composition that may translate into favorable effects in humans.

COVID-19 mRNA vaccine-mediated antibodies in human breast milk and their association with breast milk microbiota composition

Newborns can acquire immunological protection to SARS-CoV-2 through vaccine-conferred antibodies in human breast milk. However, there are some concerns around lactating mothers with regards to potential short- and long-term adverse events and vaccine-induced changes to their breast milk microbiome composition, which helps shape the early-life microbiome. Thus, we sought to explore if SARS-CoV-2 mRNA vaccine could change breast milk microbiota and how the changes impact the levels of antibodies in breast milk. We recruited 49 lactating mothers from Hong Kong who received two doses of BNT162b2 vaccine between June 2021 and August 2021. Breast milk samples were self-collected by participants pre-vaccination, one week post-first dose, one week post-second dose, and one month post-second dose. The levels of SARS-CoV-2 spike-specific IgA and IgG in breast milk peaked at one week post-second dose. Subsequently, the levels of both antibodies rapidly waned in breast milk, with IgA levels returning to baseline levels one month post-second dose. The richness and composition of human breast milk microbiota changed dynamically throughout the vaccination regimen, but the abundances of beneficial microbes such as Bifidobacterium species did not significantly change after vaccination. Additionally, we found that baseline breast milk bacterial composition can predict spike-specific IgA levels at one week post-second dose (Area Under Curve: 0.72, 95% confidence interval: 0.58–0.85). Taken together, our results identified specific breast milk microbiota markers associated with high levels of IgA in the breast milk following BNT162b2 vaccine. Furthermore, in lactating mothers, BNT162b2 vaccines did not significantly reduce probiotic species in breast milk.

Gut microbiota trajectory in β-thalassemia major children who underwent allogeneic hematopoietic stem cell transplantation.

The gut microbiota of patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT) changes, leading to complications such as acute graft-versus-host disease (GVHD). This study aimed to evaluate the human microbiota composition before and after HSCT in β-thalassemia major (β-TM) children. Twenty-two β-TM children who received allo-HSCT between December 2018 and March 2020 were enrolled. They were followed up for more than 100 days after HSCT, and their gut microbiota information and disease data were recorded at five-time points. The dominant bacteria were Bacteroidetes and Firmicutes at the phylum level and Lachnospiraceae at the family level before and after HSCT. In the differential analysis, Ruminococcaceae constantly decreased after HSCT. Besides, Rothia mucilaginosa was the most abundant 2 months after HSCT compared to before it. Additionally, GVHD patients presented decreased levels of Bacteroidetes compared to those without GVHD. Moreover, Blautia levels significantly decreased in critically ill GVHD patients. The gut microbiota of the 22 β-TM children showed a clear trend of destruction and reconstruction within 100 days after HSCT. The extra-oral infections and inflammations of Rothia mucilaginosa, a Gram-positive bacterium of the normal oropharyngeal tract microbiota, might play an important role in the recovery process of HSCT. Finally, decreased Bacteroidetes levels were associated with GVHD onset.

Simulated gastrointestinal digestion of polylactic acid (PLA) biodegradable microplastics and their interaction with the gut microbiota

The accumulation of microplastics (MPs) in the environment as well as their presence in foods and humans highlight the urgent need for studies on the effects of these particles on humans. Polylactic acid (PLA) is the most widely used bioplastic in the food industry and medical field. Despite its biodegradability, biocompatibility, and “Generally Recognized As Safe” (GRAS) status, recent animal model studies have shown that PLA MPs can alter the intestinal microbiota; however, to date, no studies have been reported on the possible gut and health consequences of its intake by humans. This work simulates the ingestion of a realistic daily amount of PLA MPs and their pass through the gastrointestinal tract by combining the INFOGEST method and the gastrointestinal simgi® model to evaluate possible effects on the human colonic microbiota composition (16S rRNA gene sequencing analysis) and metabolic functionality (lactic acid and short-chain fatty acids (SCFA) production). Although PLA MPs did not clearly alter the microbial community homeostasis, increased Bifidobacterium levels tended to increase in presence of millimetric PLA particles. Furthermore, shifts detected at the functional level suggest an alteration of microbial metabolism, and a possible biotransformation of PLA by the human microbial colonic community. Raman spectroscopy and field emission scanning electron microscopy (FESEM) characterization revealed morphological changes on the PLA MPs after the gastric phase of the digestion, and the adhesion of organic matter as well as a microbial biofilm, with surface biodegradation, after the intestinal and colonic phases. With this evidence and the emerging use of bioplastics, understanding their impact on humans and potential biodegradation through gastrointestinal digestion and the human microbiota merits critical investigation.

Gastric microbiota and its role in gastric carcinogenesis

AbstractGastric cancer (GC) is one of the most common malignancies globally, the occurrence of which undergoes a multistage chronic evolutionary process. It is a great public health issue to deeply understand the mechanisms of GC development and factors affecting the evolution of gastric lesions. Helicobacter pylori infection has been identified as one of the main factors for gastric carcinogenesis and microbial dysbiosis. With the advances in molecular biology techniques, other gastric microbes besides H. pylori have been observed to play an essential role in the development of GC. Previous animal model studies suggested that specific and critical microbes in the stomach can accelerate the malignant transformation of gastric mucosa and the progression of gastric lesions to GC. Recently, the composition of human gastric microbiota has been investigated from stages of precancerous lesions to GC, including characteristics of gastric microbiota diversity, lesion‐associated differential microbes, predicted microbiota‐related functions, microbiota interactions, and microbial mechanisms in gastric carcinogenesis. In this review, we provide an overview of the gastric microbiota, summarize current studies exploring the roles of microbiota in gastric carcinogenesis, and illustrate the significance and prospects of integrative multiomics analysis combined with the microbiome in gastric carcinogenesis.

Metabolic response of intestinal microbiota to guar gum consumption.

Guar gum is used extensively as a thickening agent in food, but it remains uncertain whether and to what extent it is fermented by colonic microbiota and whether it has microbiota modulatory properties. To determine the metabolic response of intestinal microbiota to guar gum consumption, specifically, the extent of initial fermentation and subsequent adaptation. Single-center, single arm, open label, proof-of-concept study testing the effect of guar gum on microbiota metabolism and adaptation. Healthy male subjects (n = 12) were administered gum guar (8 g/day) for 18 days. Outcomes were measured before, at initial and late administration: (a) anal gas evacuations (number/day); (b) digestive sensations (daily scales); and (c) fecal gut microbiota taxonomy and metabolic functions by shotgun sequencing. At initial consumption, guar gum induced a transient increase in anal gas evacuations and digestive sensations; gas evacuation completely reverted upon continuous administration, whereas sensations reverted only in part. Guar gum induced moderate changes in human microbiota composition at both taxonomic and functional levels. Positive associations between effects on microbiota (proliferation of Agathobaculum butyriciproducens and Lachnospira pectinoschiza) and hedonic sensations were detected. Guar gum is metabolized by intestinal microbiota, and, upon continuous consumption, induces a selective adaptation of microbial taxonomy and function. These data highlight the potential interest of guar gum for novel prebiotic ingredient formulation.

A Preliminary Study of Gut Microbiota in Airline Pilots: Comparison With Construction Workers and Fitness Instructors.

The term "WORKbiota" has been used to describe the impact of occupational exposure and work types on human microbiota composition. Airline pilots, construction workers, and fitness instructors encompass three diverse professional groups, each with distinct work environments and lifestyle factors that may significantly influence their intestinal "WORKbiota." The current preliminary investigation was aimed to compare the relative abundanceof specific gut microbes among airline pilots, construction workers, and fitness instructorsto shed light on any significant differences. By scrutinizing these diverse professional groups, our objective was to enhance our understanding of how occupational factors influence gut microbiotawhile identifying possible implications for occupational medicine. A convenience sample consisting of 60 menrepresenting three different professional domains - airline pilots, construction workers, and fitness instructors (with 20 individuals in each group) - was selected during regular outpatient occupational health consultations. The abundance of selected gut microbiota constituents, including Escherichia coli, Methanobrevibacter smithii, Akkermansia muciniphila, Faecalibacterium prausnitzii, Lactobacillus spp., Bifidobacterium spp., and Bacteroides spp., was quantified using quantitative SYBR Green quantitative real-time polymerase chain reaction (qRT-PCR) in stool samples. There were no significant variations among the groups concerning Escherichia coli, Methanobrevibacter smithii, Bifidobacterium spp., and Bacteroides spp. However, Lactobacillus spp. and Faecalibacterium prausnitzii were significantly more abundant in the microbiota of fitness instructors compared to both airline pilots and construction workers, with no significant differences observed between the latter two groups. Notably, the abundance of Akkermansia muciniphila demonstrated a progressive decline from fitness instructors to construction workersand ultimately to airline pilots, who exhibited the lowest levels. Airline pilots' gut microbiota was characterized by a lower abundance of health-promoting bacterial species, including Lactobacillus spp., Faecalibacterium prausnitzii, and Akkermansia muciniphila. Future research is essential to determine whether targeted interventions, such as probiotic and prebiotic supplementation, could potentially enhance gut microbiota composition and overall health in particular occupational groups.

The Impact of the Human Milk Microbiota in the Prevention of Disease and Infant Health.

Background: Human milk is recognized as an ideal food for newborns and infants owing to the presence of various nutritive factors, including healthy bacteria. Aim/Objective: This review aimed to understand the effects of human milk microbiota in both the prevention of disease and the health of infants. Methods: Data were obtained from PubMed, Scopus, Web of Science, clinical trial registries, Dergipark, and Türk Atıf Dizini up to February 2023 without language restrictions. Results: It is considered that the first human milk microbiota ingested by the newborn creates the initial microbiome of the gut system, which in turn influences the development and maturation of immunity. Bacteria present in human milk modulate the anti-inflammatory response by releasing certain cytokines, protecting the newborn against certain infections. Therefore, certain bacterial strains isolated from human milk could serve as potential probiotics for various therapeutic applications. Conclusions: In this review, the origin and significance of human milk bacteria have been highlighted along with certain factors influencing the composition of human milk microbiota. In addition, it also summarizes the health benefits of human milk as a protective agent against certain diseases and ailments.

Vaginal microbiota of adolescents and their mothers: A preliminary study of vertical transmission and persistence

IntroductionFactors that influence vaginal microbiota composition, including its source, are not well understood.MethodsTo determine if vaginal microbiota transmission from mother to daughter at birth could possibly influence the human vaginal microbiota composition in adolescence, we conducted a preliminary study to investigate the relationship between the vaginal microbiota of 13 adolescents (ages 15-21) and their mothers and the daughter’s birth mode.Results and discussionBased on analysis of bacterial 16S rRNA gene sequences, the vaginal microbiotas of mother/daughter pairs were more similar to each other if the daughter was born by vaginal delivery rather than by C-section. Specifically, within pair β-diversity, measured by the Yue and Clayton θ (θYC) distance metric, was significantly lower if the daughter was born by vaginal delivery. Additionally, genome sequences from an important member of the vaginal microbiota, Lactobacillus crispatus, isolated from one mother/daughter pair in which the daughter was born by vaginal delivery, were highly similar based on recombination-filtered single nucleotide polymorphisms (SNPs). Both community-level analysis and isolate genome sequence analysis are consistent with birth-mode dependent transmission and persistence of at least some members of the vaginal microbiota.

Composition and functional profiles of human faecal microbiota fermenting plant-based food particles are related to water-holding capacity more than particle size

Particle size is regarded as an important characteristic of plant-based foods in terms of digestion and fermentation. However, it is unclear to what extent the physico-chemical characteristics of different particle sizes affect microbial composition and functionality. In this study, two different particle sizes for sorghum, wheat grain, oat bran, apple, and carrot were fermented in vitro. Following fermentation, DNA was extracted and underwent 16S gene sequencing, followed by the profiling of microbial composition and predicted functions. Associations were analysed between particle size, water-holding capacity (WHC), pectin content, microbial composition and function, and in vitro gas kinetics and fermentation end-products. WHC was driven by the presence and content of pectin, and was strongly associated with both the microbial composition, and fermentation outcomes. For example, of 39 genera with a relative abundance >0.5%, the abundance of 25 genera were significantly (P < 0.05) correlated to WHC across all samples. Within the low pectin content cereal samples, when these were analysed independently of the apple and carrot samples, WHC was also associated with fermentation outcomes. For cereal and apple samples, size reduction did not lead to obvious microbial composition and functional profile changes, possibly due to the general microbial capability to degrade starch present in cereal and comparable pectin contents in apple for different sizes. However, for different sizes of carrot, the microbial composition and functional profile alterations were related to the pectin contents. Overall, the physico-chemical characteristics, such as WHC, and both pectin and starch content are related to composition and functional profiles of human faecal microbiota following in vitro fermentation.

Cervicovaginal Human Papillomavirus Genomes, Microbiota Composition and Cytokine Concentrations in South African Adolescents.

The interaction between cervicovaginal virome, bacteriome and genital inflammation has not been extensively investigated. We assessed the vaginal DNA virome from 33 South African adolescents (15-19 years old) using shotgun DNA sequencing of purified virions. We present analyses of eukaryote-infecting DNA viruses, with a focus on human papillomavirus (HPV) genomes and relate these to the vaginal bacterial microbiota (assessed by 16S rRNA gene sequencing) and cytokines (assessed by Luminex). The DNA virome included single-stranded (Anelloviridae, Genomoviridae) and double-stranded DNA viruses (Adenoviridae, Alloherpesviridae, Herpesviridae, Marseilleviridae, Mimiviridae, Polyomaviridae, Poxviridae). We identified 110 unique, complete HPV genomes within two genera (Alphapapillomavirus and Gammapapillomavirus) representing 40 HPV types and 12 species. Of the 40 HPV types identified, 35 showed positive co-infection patterns with at least one other type, mainly HPV-16. HPV-35, a high-risk genotype currently not targeted by available vaccines, was the most prevalent HPV type identified in this cohort. Bacterial taxa commonly associated with bacterial vaginosis also correlated with the presence of HPV. Bacterial vaginosis, rather than HPV, was associated with increased genital inflammation. This study lays the foundation for future work characterizing the vaginal virome and its role in women's health.

Impact of high altitude on composition and functional profiling of oral microbiome in Indian male population

The oral cavity of human contains bacteria that are critical for maintaining the homeostasis of the body. External stressors such as high altitude (HA) and low oxygen affect the human gut, skin and oral microbiome. However, compared to the human gut and skin microbiome, studies demonstrating the impact of altitude on human oral microbiota are currently scarce. Alterations in the oral microbiome have been reported to be associated with various periodontal diseases. In light of the increased occurrence of HA oral health related problems, the effect of HA on the oral salivary microbiome was investigated. We conducted a pilot study in 16 male subjects at two different heights i.e., H1 (210 m) and H2 (4420 m). Total of 31 saliva samples,16 at H1 and 15 at H2 were analyzed by utilizing the 16S rRNA high-throughput sequencing, to explore the relationship between the HA environment and salivary microbiota. The preliminary results suggesting that, the most abundant microbiome at the phylum level are: Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria. Interestingly, 11 genera were identified at the both heights with different relative abundances. In addition, the salivary microbiome was more diverse at H1 compared to H2 as demonstrated by decreased alpha diversity. Further, predicted functional results indicate that microbial metabolic profiles significantly decreased at H2 as compared to H1, including two major metabolic pathways involving carbohydrates, and amino acids. Our findings show that HA induces shifts in the composition and structure of human oral microbiota which can affect host health homeostasis.

Corrigendum: Fatty acid profile driven by maternal diet is associated with the composition of human milk microbiota

In the published article, there was an error in affiliation(s) [2]. Instead of “[Michael D. Wheeler2 and Ian N. Hines2]”, it should be “[Michael D. Wheeler4 and Ian N. Hines4]”. The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated.

The Effects of Smoking on Human Pharynx Microbiota Composition and Stability.

The oral microbiota is essential to the health of the host, yet little is known about how it responds to disturbances. We examined the oropharyngeal microbiota of 30 individuals over 40 weeks. As the oropharynx is an important gateway to pathogens, and as smoking is associated with increased incidence and severity of respiratory infections, we compared the microbiota of smokers and nonsmokers to shed light on its potential for facilitating infections. We hypothesized that decreased species diversity, decreased community stability, or increased differences in community structure could facilitate invading pathogens. We found that smoking is associated with reduced alpha diversity, greater differences in community structure, and increased environmental filtering. The effects of short-term perturbations (antibiotic use and participants exhibiting cold symptoms) were also investigated. Antibiotic use had a negative effect on alpha diversity, irrespective of smoking status, and both antibiotic use and cold symptoms were associated with highly unique bacterial communities. A stability analysis of models built from the data indicated that there were no differences in local or global stability in the microbial communities of smokers, compared to nonsmokers, and that their microbiota are equally resistant to species invasions. Results from these models suggest that smoker microbiota are perturbed but characterized by alternative stable states that are as stable and invasion-resistant as are the microbiota of nonsmokers. Smoking is unlikely to increase the risk of infectious disease through the altered composition and ecological function of the microbiota; this is more likely due to the effects of smoking on the local and systemic immune system. IMPORTANCE Smoking is associated with an increased risk of respiratory infections. Hypothetically, the altered community diversity of smokers' pharyngeal microbiota, together with changes in their ecological stability properties, could facilitate their invasion by pathogens. To address this question, we analyzed longitudinal microbiota data of baseline healthy individuals who were either smokers or nonsmokers. While the results indicate reduced biodiversity and increased species turnover in the smokers' pharyngeal microbiota, their ecological stability properties were not different from those of the microbiota of nonsmokers, implying, in ecological terms, that the smokers' microbial communities are not less resistant to invasions. Therefore, the study suggests that the increased propensity of respiratory infections that is seen in smokers is more likely associated with changes in the local and systemic immune system than with ecological changes in the microbial communities.