Frontiers in microbiomes最新文献

Obesity is a global epidemic that has affected the lives of over 14% of adults worldwide and over a third of Americans. Obesity is associated with the increased risk of thirteen obesity-associated cancers and poor cancer outcomes. Bariatric surgery is the most effective method of sustained weight loss and has been steadily increasing in clinical use over the past 4 decades. Importantly, bariatric surgery is established to decrease cancer risk. Vertical sleeve gastrectomy (VSG) is currently the most common bariatric surgery procedure. To evaluate underlying mechanisms of bariatric associated cancer protection, we developed a robust pre-clinical model of bariatric surgery-induced weight loss in mice. Using multiple strains, we established detailed procedures, defined best practices, and noted specific controls to include to examine mediators critical to cancer onset. This VSG protocol includes stringent pre- and post-operational measures to reduce stress-associated weight loss in obese mice to achieve rigorous and reproducible bariatric surgery-associated weight loss. In addition, we describe collection of fecal and intestinal samples as well as Peyer's patches as important mediators of bariatric surgery's impact on cancer risk. In conclusion, as obesity and weight loss approaches including bariatric surgery are increasingly examined in cancer risk and outcomes including immunotherapy, the establishment of robust pre-clinical interventions will allow the field to address critical underlying mechanisms mediating the benefits of weight loss and cancer.

New and noteworthy: Obesity increases cancer risk and leads to poor outcomes and survival. Bariatric surgery is an effective method of sustained weight loss. To best model obesity, weight loss, and impacts on cancer risk or outcomes, we developed a robust pre-clinical model of bariatric surgery in mice. Because bariatric surgery leads to sustained impacts on the gut microbiome, which can inform anti-tumor immunity, this protocol provides rigorous methods for the collection of intestinal microbiota and Peyer's patches.

Background and aims: Current research on host-gut microbiota interactions is hindered by almost infinite bacterial combinations depending on intrinsic characteristics, environment, and health status, which prevents large-scale screenings in mammals. For these reasons, the bacterivore model organism C. elegans has been developed to test the effects of gut microbiota extracts from mammals. This study tested whether storage conditions of mouse feces and fecal extracts modify normal C. elegans healthspan.

Methods: Feces from mice were processed for microbiota extraction after collection or after one or twelve months at -80 °C and compared to microbiota extracted six months before and left at room temperature. Extracts were probed for bacterial composition, viability, and nutritional content and tested in synchronized wild-type (strain N2) worms for food preferences and intake, development, fat accumulation, brood size, and maximal lifespan.

Results: Long-term freezing of feces before microbiota extraction modified composition but did not negatively impact subsequent worm development, fat accumulation, reproduction, and maximal lifespan, whereas using samples extracted and left at room temperature after a long period of time resulted in robust avoidance and was detrimental for normal growth.

Conclusions: Using frozen feces to test for impacts of microbiota in C. elegans appears an appropriate method since it did not affect normal biology and healthspan, which supports protocols with already existing feces stored in biobanks for high-throughput phenotype screenings.

This review focuses on the role of microorganisms in promoting health and immune function within school environments. Microbes, including bacteria, viruses, fungi, and other microorganisms, constitute the human microbiome and play a crucial role in various bodily functions and immune system development. The complex interactions between microorganisms and the immune system in schools, where children spend a significant amount of time, are not fully understood. While schools have traditionally emphasized hygiene practices to prevent the spread of infectious diseases, recent research has highlighted the potential consequences of reduced microbial exposure during early life. The "hygiene hypothesis" suggests that limited exposure to microbes in infancy may increase the risk of allergies, asthma, and autoimmune diseases in adulthood. This paper explores the microbial diversity found in schools, the benefits of exposure to different microorganisms, and the implications of hygiene practices on immune system development. It also examines current research on microbial intervention strategies and their potential to influence overall health in schools. Understanding the role of microbes in school environments has implications for public health policies and educational practices, aiming to create healthier and more conducive learning environments for the younger generation. By comprehensively exploring this topic, this review contributes to a broader understanding of the significance of microbes in promoting health and immune function in school settings and its relevance to future health research.

"Classical eutrophication" occurs when raw unfixed nutrients enter an aquatic environment. This causes the deleterious proliferation in fauna most adept at exploiting this abundance of nutrition. The net effect is de-diversification. We propose an analogous process in the gut: "gut eutrophication". Evidence shows that consumption of processed food, high in unfixed disaccharides, causes an expansion of bacteria in the gut habitat with a metabolic proclivity for these nutrients. This is at the expense of microbiota with a predilection for complex macromolecule macronutrients. There is a loss of diversity and the effect is exacerbated by a sedentary lifestyle. Gut luminal low oxygen tension favors salubrious gut commensals. This effect is potentiated by exercise but thwarted by inactivity. Antibiotics cause an obvious gut dysbiosis. So too can diet in a more insidious manner. The transition in microbial composition, seen in "gut eutrophication", may be an aetiological component of metabolic disease-associated gut dysbiosis.

Background: The tracheobronchial and oral microbiome may be associated with lung cancer, potentially acting as predictive biomarkers. Therefore, we studied the lung and oral bacteriome and virome in non-small cell lung cancer (NSCLC) patients compared to melanoma controls to discover distinguishable features that may suggest lung cancer microbial biomarkers.

Methods: In this pilot case-control study, we recruited ten patients with early-stage NSCLC (cases) and ten age-matched melanoma patients (controls) who both underwent tumor resection. Preoperative oral gargles were collected from both groups, who then underwent transbronchoscopic tracheal lavage after intubation. Lung tumor and adjacent non-neoplastic lung were sterilely collected after resection. Microbial DNA from all lung specimens underwent 16S rRNA gene sequencing. Lavage and gargle specimens underwent whole-genome shotgun sequencing. Microbiome metrics were calculated to compare both cohorts. T-tests and Wilcoxon rank sum tests were used to test for significant differences in alpha diversity between cohorts. PERMANOVA was used to compare beta diversity.

Results: No clear differences were found in the microbial community structure of case and control gargles, but beta diversity of case and control lavages significantly differed. Two species, Granulicatella adiacens and Neisseria subflava, which are both common oral commensal organisms, appeared in much higher abundance in case versus control lavages. Case lavages also maintained higher relative abundances of other oral commensals compared to controls.

Conclusions: Lung lavages demonstrated oral microbiota enrichment in cases compared to controls, suggesting microaspiration and resultant inflammation. The oral commensals Granulicatella adiacens and Neisseria subflava were more abundant in the tracheobronchial lavages of lung cancer versus melanoma patients, implicating these microorganisms as potential lung cancer biomarkers, warranting further validation studies.

Introduction: Dysfunction of keratinocytes contributes to a weakened skin barrier and impaired wound healing capability. Evidence suggests that probiotic supplementation can lead to improved skin function in vitro and in vivo. The Lab4 probiotic consortium comprises of two strains of Lactobacillus species and two strains of Bifidobacterium species.

Methods: Using serum deprived conditions to impair the functionality of immortalized human HaCaT keratinocytes, this study aimed to assess the impact of metabolites derived from the Lab4 probiotic consortium on keratinocyte function.

Results: A significant improvement in HaCaT metabolic activity and lower apoptotic activity was observed in tandem with a reduction in Caspase-3 gene expression and a lower Bax/Bcl2 ratio following the addition of Lab4. The probiotic also supported barrier integrity which was better maintained with a significant increase in Filaggrin gene expression. In damaged keratinocytes, Lab4 enhanced rates of re-epithelialization, which were associated with significantly increased gene expression of MMP-1 and enhanced secretion of IL-6 and IL-8.

Discussion: These results suggest that the Lab4 probiotic consortium may have the ability to benefit the functionality of skin.

Bacterial, fungal, and algal communities that colonize aquatic systems on glacial ice surfaces mediate biogeochemical reactions that alter meltwater composition and affect meltwater production and storage. In this study, we sought to improve understanding of microbial communities inhabiting the shallow aquifer that forms seasonally within the ice surface of a glacier's ablation zone (i.e., the weathering crust aquifer). Using a metagenomic approach, we compared gene contents of microbial assemblages in the weathering crust aquifer (WCA) of the Matanuska Glacier (Alaska, USA) to those recovered from supraglacial features and englacial ice. High abundances of Pseudomonadota, Cyanobacteriota, Actinomycetota, and Bacteroidota were observed across all samples, while taxa in class Gammaproteobacteria were found at significantly higher abundances in the weathering crust aquifer. The weathering crust aquifer samples also contained higher abundances of Dothideomycetes and Microbotryomyetes; fungal classes commonly observed in snow and other icy ecosystems. Phylogenetic analysis of 18S rRNA and rbcL gene sequences indicated high abundances of algae in the WCA that are closely related (> 98% and > 93% identity, respectively) to taxa of Ancylonema (Streptophyta) and Ochromonas (Ochrophyta) reported from glacial ice surfaces in Svalbard and Antarctic sea ice. Many functional gene categories (e.g., homeostasis, cellular regulation, and stress responses) were enriched in samples from the weathering crust aquifer compared to those from proximal englacial and supraglacial habitats, providing evidence for ecological specialization in the communities. The identification of phagotrophic phytoflagellate taxa and genes involved in mixotrophy implies that combined phototrophic and heterotrophic production may assist with persistence in the low light, low energy, and ephemeral conditions of the weathering crust environment. The compositional and functional differences we have documented indicate distinct microbial distributions and functional processes occur in the weathering crust aquifer environment, and we discuss how deciphering these nuances is essential for developing a more complete understanding of ecosystem biogeochemistry in supraglacial hydrological systems.

Introduction: Recent interest in the diverse ecosystem of bacteria, fungi and viruses that make up the skin microbiome has led to numerous studies investigating the skin microbiome in healthy skin and in dermatological conditions. However, skin microbiome analysis is challenging due to relatively low numbers of skin microorganisms compared to mucosal sites, such as the respiratory or gastrointestinal tracts. Microbiome results are heavily influenced by sampling methods. Previous sampling methods include that of cotton swabs, tape stripping, patch sampling and punch biopsies. It is essential to have a standardised sampling method for microbiome studies to have comparable results between studies. Two non-invasive methods of sampling the skin microbiome; a skin scraping versus a flocked swab were chosen as methodologies likely to be efficient, effective, and easy to access for future skin microbiome studies in children. Here we compare the two sampling methods to describe the composition of the skin microbiome in healthy children.

Method: Samples were collected from six healthy children aged three to nine years from the skin overlying the cubital fossa, cheek and axilla using (i) flocked swabs and (ii) skin scrapings with a glass slide. Samples were collected from the left and right sides of the body at two separate time points, one week apart. Quantitative PCR of the gene encoding 16S ribosomal ribonucleic acid (rRNA) was performed to compare the bacterial load collected by each sampling method. Full-length 16S rRNA gene amplicon sequencing was performed to compare the relationship of sampling method and time with the diversity and ecology of bacteria between different body sites.

Results: From six children, 78 flocked swabs and 78 skin scraping samples were collected, along with details of their overall health and skin care practices. qPCR results indicated higher total bacterial load from flocked swabs compared with skin scrapings. Flocked swabs and skin scraping methods had very similar bacterial compositional profiles. The skin microbiome was diverse between individuals and remained relatively stable within individuals over time.

Discussion: Overall, results were similar between sample types, however bacterial DNA yield was higher for flocked swab samples (compared to skin scraping methods) and with a simpler protocol is the preferred sampling method for future studies.

Introduction: The 1980 eruption of Mount St. Helens had devastating effects above and belowground in forested montane ecosystems, including the burial and destruction of soil microbes. Soil microbial propagules and legacies in recovering ecosystems are important for determining post-disturbance successional trajectories. Soil microorganisms regulate nutrient cycling, interact with many other organisms, and therefore may support successional pathways and complementary ecosystem functions, even in harsh conditions. Historic forest management methods, such as old-growth and clearcut regimes, and locations of historic short-term gopher enclosures (Thomomys talpoides), to evaluate community response to forest management practices and to examine vectors for dispersing microbial consortia to the surface of the volcanic landscape. These biotic interactions may have primed ecological succession in the volcanic landscape, specifically Bear Meadow and the Pumice Plain, by creating microsite conditions conducive to primary succession and plant establishment.

Methods and results: Using molecular techniques, we examined bacterial, fungal, and AMF communities to determine how these variables affected microbial communities and soil properties. We found that bacterial/archaeal 16S, fungal ITS2, and AMF SSU community composition varied among forestry practices and across sites with long-term lupine plots and gopher enclosures. The findings also related to detected differences in C and N concentrations and ratios in soil from our study sites. Fungal communities from previously clearcut locations were less diverse than in gopher plots within the Pumice Plain. Yet, clearcut meadows harbored fewer ancestral AM fungal taxa than were found within the old-growth forest.

Discussion: By investigating both forestry practices and mammals in microbial dispersal, we evaluated how these interactions may have promoted revegetation and ecological succession within the Pumice Plains of Mount St. Helens. In addition to providing evidence about how dispersal vectors and forest structure influence post-eruption soil microbiomes, this project also informs research and management communities about belowground processes and microbial functional traits in facilitating succession and ecosystem function.

Propionic acid (PPA), an anti-fungal agent and common food additive, has been shown to induce atypical neurodevelopment in mice, accompanied by gastrointestinal dysfunction potentially resulting from gut dysbiosis. A putative association between dietary PPA exposure and gut dysbiosis is suggested but has not been explored directly. Here, we investigated PPA-associated alteration in gut microbial composition that may result in dysbiosis. Using long-read metagenomic sequencing, gut microbiomes of mice fed an untreated (n=9) or PPA-rich (n=13) diet were sequenced to assess differences in microbial composition and bacterial metabolic pathways. Dietary PPA was associated with an increased abundance of notable taxa, including several species of Bacteroides, Prevotella, and Ruminococcus, whose member species have previously been associated with PPA production. Microbiomes of PPA exposed mice also possessed a greater abundance of pathways related to lipid metabolism and steroid hormone biosynthesis. Our findings demonstrate PPA's effect in altering the gut microbiota and associated metabolic pathways. These observed changes highlight how preservatives listed as safe for consumption may affect gut microbiome composition with implications for one's health.