The seasonal changes of the gut microbiome of the population living in traditional lifestyles are represented by characteristic species-level and functional-level SNP enrichment patterns

Epigenetic phase variation in the gut microbiome enhances bacterial adaptation

The human gut microbiome within the gastrointestinal tract continuously adapts to variations in diet, medications, and host physiology. A strategy for bacterial genetic adaptation is epigenetic phase variation (ePV) mediated by bacterial DNA methylation, which can regulate gene expression, enhance clonal heterogeneity, and enable a single bacterial strain to exhibit variable phenotypic states. Genome-wide and site-specific ePVs have been characterized in human pathogens' antigenic variation and virulence factor production. However, the role of ePV in facilitating adaptation within the human microbiome remains poorly understood. Here, we comprehensively cataloged genome-wide and site-specific ePV in human infant and adult gut microbiomes. First, using long-read metagenomic sequencing, we detected genome-wide ePV mediated by complex structural variations of DNA methyltransferases, highlighting those associated with antibiotics or fecal microbiota transplantation. Second, we analyzed a collection of public short-read metagenomic sequencing datasets, uncovering a great prevalence of genome-wide ePV in the human gut microbiome. Third, we quantitatively detected site-specific ePVs using single-molecule methylation analysis to identify dynamic variation associated with antibiotic treatment or probiotic engraftment. Finally, we performed an in-depth assessment of an Akkermansia muciniphila isolate from an infant, highlighting that ePVs can regulate gene expression and enhance the bacterial adaptive capacity by employing a bet-hedging strategy to increase tolerance to differing antibiotics. Our findings indicate that epigenetic modifications are a common strategy used by gut bacteria to adapt to the fluctuating environment.

Distinct Effects of Lactiplantibacillus plantarum HNU082 on Microbial Single-Nucleotide Variants in Large Intestine and Small Intestine

The intestinal tract extends several times the length of bodies, with varying environmental conditions across different segments (small intestinal and large intestinal), thereby harboring distinct gut microbiota. Most studies focused on the quantitative responses of gut microbiota upon probiotics entering the gut, without an in-depth analysis of how the genetic change in local gut microbiota. Therefore, in this experiment, C57BL/6J male mice were once administered Lactiplantibacillus plantarum HNU082 (Lp082). Then, the mice were euthanized on the 1st, 3rd, and 7th days after gavage, and the contents of the small and large intestines of the mice were scraped for metagenomic analysis. Based on the characterization of large intestine and small intestine bacteria, changes in the diversity and abundance of single-nucleotide variants (SNVs) of microbiota were analyzed. There were observable distinct responses at the genetic level. A significant number of SNVs were identified in Ligilactobacillus murinus in the large intestine. These SNVs may impact the utilization of carbohydrates in L. murinus. Ingested probiotics traversed the entire gut and interacted with the indigenous microbiota, driving the evolution of the indigenous gut microbiota in the different intestinal segments, thereby influencing microbial growth and metabolism. This study investigates the role of probiotics in the evolution of gut microbiota. It offers new probiotic insights and a basis for targeted interventions.

Two-Year Study on the Intra-Individual Dynamics of Gut Microbiota and Short-Chain Fatty Acids Profiles in Healthy Adults

While the gut microbiome has been intensively investigated for more than twenty years already, its role in various disorders remains to be unraveled. At the same time, questions about what changes in the gut microbiota can be considered as normal or pathological and whether communities are able to recover after exposure to negative factors (diseases, medications, environmental factors) are still unclear. Here, we describe changes in the gut microbiota composition and the content of short-chain fatty acids in adult healthy volunteers (n = 15) over a 24 month-period. Intraindividual variability in gut microbial composition was 40%, whereas the short chain fatty acids profile remained relatively stable (2-year variability 20%, inter-individual 26%). The changes tend to accumulate over time. Nevertheless, both short-term and long-term changes in the gut microbiome composition were significantly smaller within individuals than interindividual differences (two-year interindividual variability was 75%). Seasonal changes in gut microbiota were found more often in autumn and spring involving the content of minor representatives (less than 1.5% of the community in average) in the phyla Actinobacteriota, Firmicutes and Proteobacteria.

Microbial Ecology and Metabolism of Emerging Adulthood: Gut Microbiome Insights from a College Freshman Cohort

The human gut microbiome (GM) undergoes dynamic changes throughout life, transitioning from infancy to adulthood. Despite improved understanding over the past years about how genetics, lifestyle, and the external environment impact the GM, limited research has explored the GM's evolution during late-stage adolescence, especially among college students. This study addresses this gap by investigating the longitudinal dynamics of fecal microbial, functional, and metabolomic signatures in a diverse group of first-year, dormitory-housed college students. A total of 485 stool samples from 246 participants were analyzed, identifying four primary GM community types, predominantly led by Bacteroides (66.8% of samples), as well as Blautia and Prevotella. The Prevotella/Bacteroides (P/B) ratio emerged as a robust GM composition indicator, predictively associated with 15 metabolites. Notably, higher P/B ratios correlated negatively with p-cresol sulfate and cholesterol sulfate, implying potential health implications, while positively correlating with kynurenic acid. Distinct GM transition and stability patterns were found from a detailed longitudinal subset of 93 participants over an academic year. Parasutterella and the Ruminococcus gnavus group exhibited positive associations with compositional variability, whereas Faecalibacterium and Eubacterium ventriosum group displayed negative associations, the latter suggesting stabilizing roles in the GM. Most notably, nearly half of the longitudinal cohort experienced GM community shifts, emphasizing long-term GM adaptability. Comparing individuals with stable community types to those undergoing transitions, we observed significant differences in microbial composition and diversity, signifying substantial shifts in the microbiota during transitions. Although diet-related variables contributed to some observed variance, diet did not independently predict the probability of switching between community types within the study's timeframe via multi-state Markov modeling. Furthermore, exploration of stability within dynamic microbiomes among the longitudinal cohort experiencing shifts in community types revealed that microbiome taxa at the genus level exhibited significantly higher total variance than estimated functional and fecal metabolomic features. This suggests tight control of function and metabolism, despite community shifting. Overall, this study highlights the dynamic nature of the late-stage adolescent GM, the role of core taxa, metabolic pathways, the fecal metabolome, and lifestyle and dietary factors, contributing to our understanding of GM assembly and potential health implications during this life phase.

Group membership, not diet, structures the composition and functional potential of the gut microbiome in a wild primate

The gut microbiome has the potential to buffer temporal variations in resource availability and consumption, which may play a key role in the ability of animals to adapt to a broad range of habitats. We investigated the temporal composition and function of the gut microbiomes of wild common marmosets (Callithrix jacchus) exploiting a hot, dry environment-Caatinga-in northeastern Brazil. We collected fecal samples during two time periods (July-August and February-March) for 2 years from marmosets belonging to eight social groups. We used 16S rRNA gene amplicon sequencing, metagenomic sequencing, and butyrate RT-qPCR to assess changes in the composition and potential function of their gut microbiomes. Additionally, we identified the plant, invertebrate, and vertebrate components of the marmosets' diet via DNA metabarcoding. Invertebrate, but not plant or vertebrate, consumption varied across the year. However, gut microbiome composition and potential function did not markedly vary across study periods or as a function of diet composition. Instead, the gut microbiome differed markedly in both composition and potential function across marmosets residing in different social groups. We highlight the likely role of factors, such as behavior, residence, and environmental heterogeneity, in modulating the structure of the gut microbiome.

IMPORTANCE

In a highly socially cohesive and cooperative primate, group membership more strongly predicts gut microbiome composition and function than diet.

Public interest and seasonal peaks for wisdom teeth related web inquiries - A google trends analysis

Objective: The study aimed to analyze the public interest in wisdom teeth-related search terms as well as regional and seasonal trends based on information from the Google search engine.

METHODS

With the help of the online search query tool, Google Trends, the public interest in the primary search term "wisdom teeth" for the timeframe between January 1st, 2004 and September 31st, 2021 was analyzed. To do so, a country-specific search was conducted in English-speaking countries (the USA, the UK, Canada, and Australia) in the northern and southern hemispheres. The extracted time series was examined for reliability, and a Cosinor analysis evaluated the statistical significance of seasonal interest peaks.

RESULTS

The reliability of averaged time series data on the search term "wisdom teeth" was excellent in all examined countries. In all countries analyzed, "wisdom teeth removal" was one of the most common related search terms. Significant interest peaks for wisdom teeth-related search terms were found in Canada and the USA during summer (p < .001). In Canada and the USA, significant seasonal patterns with the highest interest during the summer months, could be displayed.

CONCLUSION

This phenomenon could be caused by increased wisdom teeth-related complaints induced by seasonal climate changes.

A Scoping Review Evaluating the Current State of Gut Microbiota Research in Africa

The gut microbiota has emerged as a key human health and disease determinant. However, there is a significant knowledge gap regarding the composition, diversity, and function of the gut microbiota, specifically in the African population. This scoping review aims to examine the existing literature on gut microbiota research conducted in Africa, providing an overview of the current knowledge and identifying research gaps. A comprehensive search strategy was employed to identify relevant studies. Databases including MEDLINE (PubMed), African Index Medicus (AIM), CINAHL (EBSCOhost), Science Citation index (Web of Science), Embase (Ovid), Scopus (Elsevier), WHO International Clinical Trials Registry Platform (ICTRP), and Google Scholar were searched for relevant articles. Studies investigating the gut microbiota in African populations of all age groups were included. The initial screening included a total of 2136 articles, of which 154 were included in this scoping review. The current scoping review revealed a limited number of studies investigating diseases of public health significance in relation to the gut microbiota. Among these studies, HIV (14.3%), colorectal cancer (5.2%), and diabetes mellitus (3.9%) received the most attention. The top five countries that contributed to gut microbiota research were South Africa (16.2%), Malawi (10.4%), Egypt (9.7%), Kenya (7.1%), and Nigeria (6.5%). The high number (n = 66) of studies that did not study any specific disease in relation to the gut microbiota remains a gap that needs to be filled. This scoping review brings attention to the prevalent utilization of observational study types (38.3%) in the studies analysed and emphasizes the importance of conducting more experimental studies. Furthermore, the findings reflect the need for more disease-focused, comprehensive, and population-specific gut microbiota studies across diverse African regions and ethnic groups to better understand the factors shaping gut microbiota composition and its implications for health and disease. Such knowledge has the potential to inform targeted interventions and personalized approaches for improving health outcomes in African populations.

Clostridium butyricum Potentially Improves Immunity and Nutrition through Alteration of the Microbiota and Metabolism of Elderly People with Malnutrition in Long-Term Care

Recent research advances examining the gut microbiome and its association with human health have indicated that microbiota-targeted intervention is a promising means for health modulation. In this study, elderly people in long-term care (aged 83.2 ± 5.3 year) with malnutrition (MNA-SF score ≤ 7) were recruited in a community hospital for a 12-week randomized, single-blind clinical trial with Clostridium butyricum. Compared with the basal fluctuations of the control group, an altered gut microbiome was observed in the intervention group, with increased (p < 0.05) Coprobacillus species, Carnobacterium divergens, and Corynebacterium_massiliense, and the promoted growth of the beneficial organisms Akketmanse muciniphila and Alistipes putredinis. A concentrated profile of 14 increased Kyoto Encyclopedia of Genes and Genomes (KEGG) orthologs (KOs) that were enriched in cofactor/vitamin production and carbohydrate metabolism pathways were discovered; the genes were found to be correlated (p < 0.05) with an elevated abundance of plasma metabolites and short-chain fatty acids (SCFAs), unsaturated medium- to long-chain fatty acids (MFA, LFA), carnitines, and amino acids, thus suggesting a coordinated ameliorated metabolism. Proinflammatory factor interferon-gamma (IFN-γ) levels decreased (p < 0.05) throughout the intervention, while the gut barrier tight junction protein, occludin, rose in abundance (p = 0.059), and the sensitive nutrition biomarker prealbumin improved, in contrast to the opposite changes in control. Based on our results obtained during a relatively short intervention time, C. butyricum might have great potential for improving nutrition and immunity in elderly people in long-term care with malnutrition through the alteration of gut microbiota, increasing the abundance of beneficial bacteria and activating the metabolism in SCFA and cofactor/vitamin production, bile acid metabolism, along with efficient energy generation.