Diversity Of Operational Taxonomic Units Research Articles

Characterization of the oral microbiome and gut microbiome of dental caries and extrinsic black stain in preschool children.

A lower prevalence of dental caries (hereafter termed "caries") has been observed in children with dental extrinsic black stain (EBS). We investigated the epidemiologic characterization of EBS and explored the possible role of the oral microbiome (OM) and gut microbiome (GM) in EBS formation and caries prevention. In an epidemiologic survey, 2,675 children aged 3-6 years were included. Thirty-eight of these children (7 children had both caries and EBS, 10 had EBS only, 11 had caries only, and 10 were healthy children) were recruited for 16S rRNA sequencing and collection of samples of supragingival plaque and feces. Collected plaque samples were divided into four groups: BCP (EBS+, caries+), BP (EBS+, caries-), CP (EBS-, caries+), and P (EBS-, caries-). Fecal samples were also divided into four groups: BCF (EBS+, caries+), BF (EBS+, caries-), CF (EBS-, caries+), and F (EBS-, caries-). EBS was observed in 12.10% of this population. Children with EBS had a significantly reduced prevalence of caries and a lower mean value of decayed-missing-filled teeth (dmft; p < 0.01). According to analyses of dental plaque, the P group had the most complex microbiome. The BCP group exhibited greater operational taxonomic unit (OTU) richness but a reduced evenness compared with the BP group, and the CP group showed greater OTU richness than the BP group. At the genus level, higher abundance of Actinomyces and Cardiobacterium species was observed in the BCP group. Higher abundance of Lautropia and Pesudopropionibacteriumin species was observed in the BP group compared with P and CP groups, respectively (p < 0.05). Veillonella species were significantly more common in P and CP groups than in BP groups, whereas Porphyromonas and Fusobacterium species were more common in the CP group (p < 0.05). With regard to the GM, the CF group exhibited greater OTU diversity than the BF group. The GM in the BCF group exhibited the most complex relationships across all fecal groups. GM groups could be distinguished by various unique biomarkers, such as Escherichia and Shigella species in the BCF group, Agathobacter and Ruminococcus species in the CF group, Lactobacillus species in the BF group, and Roseburia species in the F group. Our results suggest that EBS is a possible protective factor against early-childhood caries. Dental plaque and the GM may be relevant to EBS in primary dentition.

Integrated analysis of the gut microbiome and metabolome in a mouse model of inflammation-induced colorectal tumors.

Colorectal cancer (CRC) is a common malignancy worldwide, and the gut microbiota and metabolites play an important role in its initiation and progression. In this study, we constructed a mouse model of inflammation-induced colorectal tumors, with fixed doses of azoxymethane/dextran sulfate sodium (AOM/DSS). We found that colorectal tumors only formed in some mice treated with certain concentrations of AOM/DSS (tumor group), whereas other mice did not develop tumors (non-tumor group). 16S rDNA amplicon sequencing and liquid chromatography-mass spectrometry (LC-MS)/MS analyses were performed to investigate the microbes and metabolites in the fecal samples. As a result, 1189 operational taxonomic units (OTUs) were obtained from the fecal samples, and the non-tumor group had a relatively higher OTU richness and diversity. Moreover, 53 different microbes were identified at the phylum and genus levels, including Proteobacteria, Cyanobacteria, and Prevotella. Furthermore, four bacterial taxa were obviously enriched in the non-tumor group, according to linear discriminant analysis scores (log10) > 4. The untargeted metabolomics analysis revealed significant differences between the fecal samples and metabolic phenotypes. Further, the heatmaps and volcano plots revealed 53 and 19 dysregulated metabolites between the groups, in positive and negative ion modes, respectively. Styrene degradation and amino sugar-nucleotide sugar metabolism pathways were significantly different in positive and negative ion modes, respectively. Moreover, a correlation analysis between the metabolome and microbiome was further conducted, which revealed the key microbiota and metabolites. In conclusion, we successfully established a tumor model using a certain dose of AOM/DSS and identified the differential intestinal microbiota and characteristic metabolites that might modulate tumorigenesis, thereby providing new concepts for the prevention and treatment of CRC.

Effect of dung and dung beetle application on topsoil fungal assemblage of a post-coal mining reclamation land: Towards soil health improvement

Soil management practices such as organic matter input can ameliorate soil health, including microbial communities that are crucial for ecological processes. In this study, the effect of successive application of cattle dung and/or dung beetle on the diversity and ecological guild of topsoil fungal assemblages on a post-coal mining reclaimed site was investigated. Three experimental treatments namely: dung plus dung beetles (dung + beetle), dung only (dung-only), and no dung, no dung beetle (control) was established on 4-m2 subplots on a ≥16-year-old post-coal mining reclamation area. Following a 17-month experimental period, topsoil fungal assemblage was determined using next-generation sequencing of fungal ribosomal internally transcribed spacer 2 region. The highest operational taxonomic unit (OTU) richness and Shannon-Wiener diversity were obtained in the dung-only treatment while the lowest OTU richness and diversity was obtained in control treatment. Although not statistically significant, a trend towards lower OTU richness in the topsoil was observed with the addition of dung beetle compared to the only dung treatment. In multivariate space, fungal communities were differentiated between dung-only and control, suggesting the influence of dung addition. Overall, dung addition primarily improved topsoil fungal diversity and the abundance of beneficial plant-fungal symbionts important for nutrient mobilisation in the soil, with a trend towards lower diversity observed with dung beetle addition suggesting possible vertical displacement of organic matter and ecologically relevant fungal species to deeper soil depths.

Bacterial communities in sediments of an urban wetland in Bogota, Colombia

Urban wetlands are biodiversity reservoirs sustained by microbe-mediated processes. In tropical zones, wetland microbial dynamics remain poorly understood. Chemical parameters, heavy metal content, and microbiological community structure were investigated in surface sediments of the Santa Maria del Lago (SML) wetland in Bogota, Colombia. High-throughput sequencing was employed to generate RNAr 16S and nosZ gene sequence data with which bacteria, archaea, and nosZ-type denitrifier community composition and their phylogenetic relationships were investigated. A canonical correspondence analysis was conducted to determine the relationship between assessed environmental variables and microbial community composition. Results showed that the most abundant bacterial phyla were Proteobacteria, Acidobacteria (group GP18), and Aminicenantes; Archaea were represented by the taxa Methanomicrobia and Thermoprotei, and the nosZ community was dominated by Candidatus Competibacter denitrificans. A phylogenetic analysis revealed a high diversity of Operational Taxonomic Units (OTUs), according to 16S rRNA gene sequence data; however, the quantity and diversity of OTUs from the nosZ community were low compared to previous studies. High concentrations of ammonium, phosphorus, organic carbon, Pb, Fe, Zn, Cu, and Cd, were detected in sediments, but they were not strongly related to observed microbial community compositions. In conclusion, in the same polluted SML wetland sediments diverse bacteria and archaea communities were detected, although not nosZ-type denitrifiers.

Community structure and environmental determinants of the bacterial and fungal gut microflora in Hainan gibbons (Nomascus hainanus)

High-throughput sequencing technology was used to establish the OTU (Operational Taxonomic Units) composition and diversity of bacteria and fungi in the gut of three family groups of Hainan gibbons ( Nomascus hainanus ) in the Bawangling National Nature Reserve on Hainan Island, southern China. Firmicutes (47.23%) and Bacteroidetes (36.54%) predominated at the phylum level, while the predominant genera were Prevotella-7 (15.30%), Lachnospiraceae_NK3A20_group (12.49%), and uncultured_bacterium_f_Erysipelotrichaceae (11.79%). At the phylum level, the dominant fungi were Ascomycota (66.41%), as well as Hanseniaspora (23.33%), Schwanniomyces (13.44%), and Pichia (5.43%) at the genus level. We found significant differences in the bacterial OTU diversity (Shannon index) between family groups living in Tropical Lowland or Tropical Montane Rain Forest, compared to those inhabiting Tropical Montane Evergreen Forest at higher altitudes. Bacterial OTU community composition also differed between family groups, unraveling significant differences among the 30 most dominant bacterial core taxa. Furthermore, we unraveled a significant difference of OTU richness in the fungal microbiome (Chao 1) between family groups living at lower altitudes, i.e., Tropical Lowland or Tropical Montane Rain Forest and those inhabiting the Tropical Montane Evergreen Forest. Our analysis further indicated significant differences in the fungal OTU community composition between the three family groups, especially regarding the three most dominant fungal core taxa. Subsequently, two habitat factors, and nine environmental and anthropogenic variables were used to explore possible causes of disparity in the microbial flora of gibbon groups. A factor reduction procedure resulted into three principal components which were correlated to bacterial and fungal OTU richness and diversity using Spearman's rank-order correlations. Bacterial and fungal OTU diversity was high in areas of high altitude, steep slopes, high tree density, but low tree height, while high fungal OTU richness corresponded to high altitude habitats, i.e., in the Tropical Montane Evergreen Forest. Distance to human settlements and to the next water body showed no significant relation with bacterial and fungal richness and diversity.

Molecular insight reveals broad-scale spatial patterns in floodplain ciliate assemblages, whereas morphology reflects local environmental controls

One of the major goals in microbial ecology is to understand whether the empirical biogeographic patterns of macroorganisms also apply to microorganisms. Here, we used morphological data from live organisms, along with molecular data, to investigate the importance of spatial factors and environmental variables in influencing ciliate composition from floodplain lakes. Our main goal was to use 2 different approaches (morphological and molecular) to compare ciliate diversity and distribution patterns as well as to compare how these methods differ in their ability to detect distribution patterns and the roles of spatial and environmental factors that shape ciliate assemblages in the 4 largest floodplains in Brazil. Planktonic water samples were gathered from 33 lakes associated with 4 different river floodplain systems in Brazil. We analyzed ciliates in vivo and sequenced surface water DNA using a metabarcoding approach with general eukaryotic primers. We showed that the diversity of operational taxonomic units was much higher than that of morphospecies. Regardless of the method of identification, we found a consistent spatial assembly pattern of ciliate assemblages across the 4 floodplain systems. We also found that environmental filters had a stronger association with the morphological than with the molecular site-by-site dissimilarities. Meanwhile, biogeographic factors and the distance among sites limited the distribution of molecular-based composition, resulting in strong differences among the floodplain lakes analyzed. This finding suggests that ecological research and biomonitoring activities should find an equilibrium between morphological and molecular approaches because each approach provides unique insights.

DNA metabarcoding reveals vertical variation and hidden diversity of Alveolata and Rhizaria communities in the western North Pacific

Metabarcoding technology using high-throughput sequencing has revolutionized the current understanding of the diversity and ecology of eukaryotic microorganisms. The aim of the present study was to investigate vertical and seasonal variation in eukaryotic plankton communities and to assess the diversity of eukaryotic plankton, using 18S rRNA sequencing, over a depth gradient in subtropical waters affected by the Kuroshio Current. In particular, the present study focused on the diversity and ecology of Alveolata and Rhizaria taxa, which include a variety of plankton species with fragile skeletons or soft bodies. Three vertically distinct eukaryotic communities were identified: the Kuroshio-influenced epipelagic zone (<200 m), the North Pacific Intermediate Water (NPIW)-dominated mesopelagic zone (500–1000 m), and the bathypelagic zone (2000–3000 m). The operational taxonomic unit (OTU) richness was greatest near the surface (<200 m depth), gradually decreasing with increasing depth, and lowest in deeper layers, and OTU diversity (Pielou's evenness and Shannon-Wiener diversity indices) were lowest in the mesopelagic layer (500–1000 m depth). Hidden diversity was observed in both groups in both the surface and deeper layers of the western North Pacific, as well as in the NPIW, which was characterized by the lowest salinity and oxygen concentrations in the study area. In the NPIW, the Rhizaria yielded relatively more sequence reads than other taxa. Furthermore, specific taxa, such as Collodaria (Radiolaria), Syndiniales (dinoflagellates), and Oligohymenophorea (ciliates), were predominant, according to OTU richness and the relative abundance of sequence reads. These findings indicate that a unique ecosystem was formed over time in the NPIW-isolated water mass.

Effects of drinking water supplementation with Lactobacillus reuteri, and a mixture of reuterin and microcin J25 on the growth performance, caecal microbiota and selected metabolites of broiler chickens

BackgroundSince the overuse of antibiotics in animal production has led to a selection of antibiotic-resistant pathogens that affect humans and animals as well. Scientists are therefore searching for novel natural alternatives to antibiotics. In this study Lactobacillus reuteri and a combination of reuterin and microcin J25 (RJ) were evaluated as promoters of growth and modulators of the cecal microbiota and metabolite profiles in broiler chickens. One-day-old Cobb 500 male broilers were distributed to 8 treatments: negative control (without antibiotic), positive control (bacitracin), three concentrations of RJ and three doses of L. reuteri plus glycerol. The birds (2176, 34 per pen, 8 pens per treatment) were reared for 35 d.ResultsThe body weight of the bacitracin and 5 mmol/L reuterin combined with 0.08 μmol/L microcin J25 (10RJ) treatment group was significantly higher than that of the negative control group (P < 0.05). L. reuteri had no significant effect on broiler growth. MiSeq high-throughput sequencing of 16S rRNA showed clustering of cecal microbial operational taxonomic unit diversity according to treatment. The influence of bacitracin and 10RJ on bacterial community overall structure was similar. They promoted Ruminococcaceae, Lachnospiraceae and Lactobacillaceae, increased the relative abundance of Faecalibacterium and decreased the abundance of Bacteroides and Alistipes, while the negative control condition favored Bacteroidaceae and Rikenellaceae. Furthermore, 10RJ increased the concentration of short-chain fatty acid in the cecum and changed the metabolome overall.ConclusionsThese overall suggest that 10RJ can promote a host-friendly gut environment by changing the cecal microbiome and metabolome. This combination of natural antimicrobial agents in the drinking water had a positive effect on broiler growth and may be suitable as an alternative to antibiotic growth promoters.

Comparison of Bacterial Community of Healthy and Erwinia amylovora Infected Apples.

Fire blight disease, caused by Erwinia amylovora, could damage rosaceous plants such as apples, pears, and raspberries. In this study, we designed to understand how E. amylovora affected other bacterial communities on apple rhizosphere; twig and fruit endosphere; and leaf, and fruit episphere. Limited studies on the understanding of the microbial community of apples and changes the community structure by occurrence of the fire blight disease were conducted. As result of these experiments, the infected trees had low species richness and operational taxonomic unit diversity when compared to healthy trees. Rhizospheric bacterial communities were stable regardless of infection. But the communities in endosphere and episphere were significanlty affected by E. amylovora infection. We also found that several metabolic pathways differ significantly between infected and healthy trees. In particular, we observed differences in sugar metabolites. The finding provides that sucrose metabolites are important for colonization of E. amylovora in host tissue. Our results provide fundamental information on the microbial community structures between E. amylovora infected and uninfected trees, which will contribute to developing novel control strategies for the fire blight disease.

Diet-induced microbiome shifts of sympatric overwintering birds.

Gut microbiota have a significant impact on host physiology and health, and host genetics and diet are considered as two important factors, but it is difficult to discriminate the influence of each single factor (host or diet) on gut microbiota under natural conditions. Moreover, current studies of avian microbiota mainly focus on domestic or captive birds, and it is still uncertain how host and diet take part in changing avian gut microbiota composition, diversity, and function in the wild. Here, high-throughput sequencing of 16S rRNA was used to identify the gut microbiota communities for sympatric wintering Great Bustards and Common Cranes at different diets. The results showed that 8.87% operational taxonomic units (OTUs) were shared among all sampling birds; in contrast, 39.43% of Kyoto Encyclopedia of Genes and Genomes (KEGG) functional pathways were common among all individuals, indicating the existence of gut microbiota conservatism both in microbiota structure and function. Microbiota abundance and diversity differed between Great Bustards and Common Cranes in a specific wintering site, and microbiota variation was detected for the same host species under two different sites, suggesting that the change of gut microbiota was induced by both host and diet. Furthermore, we found that changes of both microbial communities and functional pathways were larger between hosts than those between diets, which revealed that host might be the dominant factor determining microbiota characteristics and function, while diet further drove the divergence of gut microbiota. Gut microbiota functions appeared to be more conserved than bacterial community structure, indicating that different bacteria may function in a similar way, while microbiota OTU diversity might not be necessarily associated with functional diversity. With diet shifting, gut microbiota changed both in terms of microbial communities and functional pathways for the sympatric birds, which implies that avian habitats and their physiological microbiota would be influenced by different farmland management regimes. KEY POINTS: • Gut microbiota can be shaped by both diets and hosts in sympatric species. • Host was the dominant factor shaping the gut microbiota communities and functional pathways. • Gut microbiota were conservative both in structure and in function, but more conservative in function.

Gut microbiota in Immunoglobulin A Nephropathy: a Malaysian Perspective

IntroductionThe alteration of the gut microbiome in the gut-kidney axis has been associated with a pro-inflammatory state and chronic kidney disease (CKD). A small-scaled Italian study has shown an association between the gut microbiome and Immunoglobulin A Nephropathy (IgAN). However, there is no data on gut microbiota in IgAN in the Asian population. This study compares the gut microbial abundance and diversity between healthy volunteers and Malaysian IgAN cohort.MethodsA comparative cross-sectional study was conducted involving biopsy-proven IgAN patients in clinical remission with matched controls in a Malaysian tertiary centre. Demographic data, routine blood and urine results were recorded. Stool samples were collected and their DNA was extracted by 16S rRNA gene sequencing to profile their gut microbiota.ResultsThirty-six IgAN patients (13 male; 23 female) with the mean age of 45.5 ± 13.4 years and median estimated glomerular filtration rate (eGFR) of 79.0 (62.1–92.2) mls/min/1.73m2 with median remission of 7 years were analysed and compared with 12 healthy controls (4 male; 8 female) with the mean age of 46.5 ± 13.5 years and eGFR of 86.5 (74.2–93.7) mls/min/1.73m2. Other demographic and laboratory parameters such as gender, ethnicity, body mass index (BMI), haemoglobin, serum urea and serum albumin were comparable between the two groups. There were no significant differences seen in the Operational Taxonomic Unit (OTU) and alpha diversity (Shannon index) between IgAN and healthy controls. Alpha diversity increased with increasing CKD stage (p = 0.025). Firmicutes/Bacteroidetes (F/B) ratio was low in both IgAN and healthy cohort. Fusobacteria phylum was significantly increased (p = 0.005) whereas Euryarchaoeota phylum was reduced (p = 0.016) in the IgAN group as compared to the control cohort.ConclusionAlthough we found no differences in OTU and alpha diversity between IgAN in remission and control cohort, there were some differences between the two groups at phylum level.

Probiotic Bacillus subtilis 29,784 improved weight gain and enhanced gut health status of broilers under necrotic enteritis condition

The study investigated the benefit of a Bacillus subtilis probiotic (Bs 29,784) in necrotic enteritis (NE)–challenged broilers. Four treatments were performed with 312 male day-old Ross 308 reared in floor pens from day 0 to day 35: 2 groups fed control diet without or with NE challenge (CtrlNC and CtrlNE); 2 groups fed probiotic and antibiotic supplements in the control diet with NE challenge (ProNE and AntNE). Necrotic enteritis challenge procedures commenced with inoculation of Eimeria spp 1 mL/bird per os at day 9 and Clostridium perfringens EHE-NE18 (approximately 108 cfu/mL) 1 mL/bird per os at day 14 and day 15. Performance parameters were measured on day 16 and day 35. Lesion, cecal microbiota, and jejunal gene expression were analyzed on day 16. Necrotic enteritis challenge significantly suppressed the performance parameters compared with CtrlNC: 27% weight gain reduction, 11 points feed conversion ratio (FCR) increase at day 16, and 12% weight gain reduction, 5-point FCR increase at day 35. By day 35, ProNE and AntNE treatments enabled significantly higher weight gain (4 and 9%, respectively) than CtrlNE. Compared with CtlrNE and contrary to AntNE, ProNE treatment exhibited upregulation of genes coding for tight junctions proteins (CLDN1, JAM2, TJP1), cytokines (IL12, interferon gamma, TGFβ), and Toll-like receptors (TLR5, TLR21) suggesting enhanced immunity and intestinal integrity. 16S NGS analysis of cecal microbiota at day 16 showed a decreased alpha diversity in challenged groups. Principal component analysis of operational taxonomic unit (OTU) abundance revealed that ProNE and AntNE grouped closely while both distantly from CtrlNC and CtrlNE, which were separately grouped, indicating the similar effects of ProNE and AntNE on the OTU diversity that were however different from both CtrlNC and CtrlNE. Microbiota analysis revealed an increase of genera Faecalibacterium, Oscillospira, and Butyricicoccus; and a decrease of genera Ruminococcus, Lactobacillus, and Bacteroides; and an increase of the Firmicutes-to-Bacteroidetes ratio in ProNE and AntNE groups compared with the CtlrNE group. It is concluded that Bs 29,784 may enable improved health of broiler chickens under NE conditions thus performance implications.

Revealing an Invasion Risk of Fish Species in Qingdao Underwater World by Environmental DNA Metabarcoding

Environmental DNA (eDNA) metabarcoding has emerged as a potentially powerful tool to monitor invasive fish species. As an alternative (or complementary) tool for biodiversity monitoring, eDNA metabarcoding had been used to detect species in aquariums, which represents an important transit avenue for introducing non-indigenous species with high population densities. In this study, eDNA metabarcoding as well as morphological characterization were used to reveal the diversity of non-indigenous species in a large aquarium at Qingdao Underwater World. Environmental DNA metabarcoding of 14 water samples at five locations from the Big Water Tank detected 24 non-indigenous species and four putative non-indigenous operational taxonomic units (OTUs). In contrast, only 20 non-indigenous species were observed by morphological characterization. Some species undetected by morphological characterization, such as Oreochromis niloticus (Linnaeus, 1758), are highly adaptable to various environments and/or have invaded preferred regions where they threaten native aquatic species. eDNA metabarcoding also detected seven local fishes that were not identified by morphological characterization. However, analysis of OTU diversity among stations and sample replications revealed that eDNA varied within and/or between stations. Increasing sampling effort as well as negative controls are required to increase the detection rate of species and to eliminate false-positive OTUs.

Unearthing the sand microbiome of sea turtle nests with disparate survivorship at a mass-nesting beach in Costa Rica

For endangered sea turtle populations, microbial pathogens of developing embryos are of concern at nesting sites around the globe. For olive ridley turtles, hatching success is markedly lower at mass-nesting sites than at solitary nesting beaches, a case presumably resulting from the abundance of decomposing eggs generated by nesting turtles destroying adjacent eggs. This organic input drives microbial activity, affecting the nest environment (i.e. pO2and temperature), and reducing embryo survivorship and hatching success. However, the composition of microbial communities in nest sand has not been studied in detail and the presence of potential pathogens can, therefore, not be discounted. As a part of a larger study that investigated microbial abundance in nests, we employed high-throughput DNA sequencing to compare fungal and bacterial composition in nest sand from areas of disparate embryo survivorship. While we found no differences in alpha-diversity (mean operational taxonomic unit diversity within each site) among nesting areas, the microbial community composition of each area was distinct, and differences in community structure corresponded with variable hatching success. Some sequences of potential sea turtle egg pathogens were obtained (e.g.Fusarium solanispecies complex), but were in low relative abundance, and their presence was not associated with low hatching success. Our results from the arribada beach at Ostional, Costa Rica, provide further evidence that the physical characteristics of the nest (including those that determine microbial composition and activity) are likely more relevant to hatching success than the presence of potential pathogens or microbial community structure alone.

Can metabarcoding resolve intraspecific genetic diversity changes to environmental stressors? A test case using river macrozoobenthos

Genetic diversity is the most basal level of biodiversity and determines the evolutionary capacity of species to adapt to changing environments, yet it is typically neglected in routine biomonitoring and stressor impact assessment. For a comprehensive analysis of stressor impacts on genetic diversity, it is necessary to assess genetic variants simultaneously in many individuals and species. Such an assessment is not as straightforward and usually limited to one or few focal species. However, nowadays species diversity can be assessed by analysing thousands of individuals of a community simultaneously with DNA metabarcoding. Recent bioinformatic advances also allow for the extraction of exact sequence variants (ESVs or haplotypes) in addition to Operational Taxonomic Units (OTUs). By using this new capability, we here evaluated if the analysis of intraspecific mitochondrial diversity in addition to species diversity can provide insights into responses of stream macrozoobenthic communities to environmental stressors. For this purpose, we analysed macroinvertebrate bulk samples of three German river systems with different stressor levels using DNA metabarcoding. While OTU and haplotype number were negatively correlated with stressor impact, this association was not as clear when studying haplotype diversity across all taxa. However, stressor responses were found for sensitive EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa and those exceedingly resistant to organic stress. An increase in haplotype number per OTU and haplotype diversity of sensitive taxa was observed with an increase in ecosystem quality and stability, while the opposite pattern was detected for pollution resistant taxa. However, this pattern was less prominent than expected based on the strong differences in stressor intensity between sites. To compare genetic diversity among communities in river systems, we focussed on OTUs, which were present in all systems. As OTU composition differed strongly between rivers, this led to the exclusion of a high number of OTUs, especially in diverse river systems of good quality, which potentially diminished the increase in intraspecific diversity. To better understand responses of intraspecific genetic diversity to environmental stressors, for example in river ecosystems, it would be important to increase OTU overlap between compared sites, e.g. by sampling a narrower stressor gradient, and to perform calibrated studies controlling for the number of individuals and their haplotypes. However, this pioneer study shows that the extraction of haplotypes from DNA metabarcoding datasets is a promising source of information to simultaneously assess intraspecific diversity changes in response to environmental impacts for a metacommunity.

Spatial variation in diet-microbe associations across populations of a generalist North American carnivore.

Generalist species, by definition, exhibit variation in niche attributes that promote survival in changing environments. Increasingly, phenotypes previously associated with a species, particularly those with wide or expanding ranges, are dissolving and compelling greater emphasis on population-level characteristics. In the present study, we assessed spatial variation in diet characteristics, gut microbiome and associations between these two ecological traits across populations of coyotes Canis latrans. We highlight the influence of the carnivore community in shaping these relationships, as the coyote varied from being an apex predator to a subordinate, mesopredator across sampled populations. We implemented a scat survey across three distinct coyote populations in Michigan, USA. We used carbon (δ13 C) and nitrogen (δ15 N) isotopic values to reflect consumption patterns and trophic level, respectively. Corresponding samples were also paired with 16S rRNA sequencing to describe the microbial community and correlate with isotopic values. Although consumption patterns were comparable, we found spatial variation in trophic level among coyote populations. Specifically, δ15 N was highest where coyotes were the apex predator and lowest where coyotes co-occurred with grey wolves Canis lupus. The gut microbial community exhibited marked spatial variation across populations with the lowest operational taxonomic units diversity found where coyotes occurred at their lowest trophic level. Bacteriodes and Fusobacterium dominated the microbiome and were positively correlated across all populations. We found no correlation between δ13 C and microbial community attributes. However, positive associations between δ15 N and specific microbial genera increased as coyotes ascended trophic levels. Coyotes provide a model for exploring implications of niche plasticity because they are a highly adaptable, wide-ranging omnivore. As coyotes continue to vary in trophic position and expand their geographic range, we might expect increased divergence within their microbial community, changes in physiology and alterations in behaviour.

Differences in community composition of endophytic fungi between above- and below-ground tissues of Aristolochia chilensis in an arid ecosystem

BackgroundEndophytic fungi are diverse and ubiquitous in nature, yet studies simultaneously comparing endophyte communities in above- and below-ground plant tissues are relatively scarce. The main goal of our study was to compare the diversity and community composition of endophytic fungi associated with above- and below-ground tissues of the plant Aristolochia chilensis in an arid ecosystem. Endophytic fungi were isolated from healthy leaves and roots of A. chilensis, and the internal transcribed spacer (ITS) region was sequenced for phylogenetic and taxonomic analysis.ResultsA combined total of 457 fungal isolates were cultured from leaf and root tissues, belonging to 54 operational taxonomic units (OTUs). The genera Fusarium, Penicillium, Phialemonium and Trichoderma were the most representative endophyte taxa identified in A. chilensis tissues; nevertheless, Fusarium was significantly more dominant in the below-ground community, while foliar endophyte community was dominated by Penicillium. Whereas OTU richness and diversity were not different between below-ground and above-ground tissues, endophyte abundance was on average twice as high in below-ground tissue than in above-ground tissue. Fungal endophyte communities in the two tissue types were significantly dissimilar.ConclusionsResults from this study indicate that A. chilensis harbors a similar diversity of endophytic fungi in above- and below-ground tissues. Dominant endophytic fungi were found to be dependent on tissue type, which potentially resulted in marked differences in community structure between above- and below-ground tissues. Ecological processes potentially affecting this pattern are discussed.

Beyond host regulation: Changes in gut microbiome of permissive and non-permissive hosts following parasitization by the wasp Cotesia flavipes.

Koinobiont parasitoids regulate the physiology of their hosts, possibly interfering with the host gut microbiota and ultimately impacting parasitoid development. We used the parasitoid Cotesia flavipes to investigate if the regulation of the host would also affect the host gut microbiota. We also wondered if the effects of parasitization on the gut microbiota would depend on the host-parasitoid association by testing the permissive Diatraea saccharalis and the non-permissive Spodoptera frugiperda hosts. We determined the structure and potential functional contribution of the gut microbiota of the fore-midgut and hindgut of the hosts at different stages of development of the immature parasitoid. The abundance and diversity of operational taxonomic units of the anteromedial (fore-midgut) gut and posterior (hindgut) region from larvae of the analyzed hosts were affected by parasitization. Changes in the gut microbiota induced by parasitization altered the potential functional contribution of the gut microbiota associated with both hosts. Our data also indicated that the mechanism by which C. flavipes interferes with the gut microbiota of the host does not require a host-parasitoid coevolutionary history. Changes observed in the potential contribution of the gut microbiota of parasitized hosts impact the host's nutritional quality, and could favor host exploitation by C. flavipes.

Neonatal Diet Impacts Bioregional Microbiota Composition in Piglets Fed Human Breast Milk or Infant Formula

Early infant diet influences postnatal gut microbial development, which in turn can modulate the developing immune system. The aim of this study was to characterize diet-specific bioregional microbiota differences in piglets fed either human breast milk (HM) or infant formula. Male piglets (White Dutch Landrace Duroc) were raised on HM or cow milk formula (MF) from postnatal day (PND) 2 to PND 21 and weaned to an ad libitum diet until PND 51. Piglets were euthanized on either PND 21 or PND 51, and the gastrointestinal contents were collected for 16s RNA sequencing. Data were analyzed using the Quantitative Insight into Microbial Ecology. Diversity measurements (Chao1 and Shannon) and the Wald test were used to determine relative abundance. At PND 21, the ileal luminal region of HM-fed piglets showed lower Chao1 operational taxonomic unit diversity, while Shannon diversity was lower in cecal, proximal colon (PC), and distal colon (DC) luminal regions, relative to MF-fed piglets. In addition, at PND 51, the HM-fed piglets had lower genera diversity within the jejunum, ileum, PC, and DC luminal regions, relative to MF-fed piglets. At PND 21, Turicibacter was 4- to 5-fold lower in the HM-fed piglets' ileal, cecal, PC, and DC luminal regions, relative to the MF-fed piglets. Campylobacter is 3- to 6-fold higher in HM-fed piglets duodenal, ileal, cecal, PC, and DC luminal regions, in comparison to MF-fed piglets. Furthermore, the large intestine (cecum, PC, and rectum) luminal region of HM-fed piglets showed 4- to 7-fold higher genera that belong to class Bacteroidia, in comparison to MF-fed piglets at PND 21. In addition, at PND 51 distal colon lumen of HM-fed piglets showed 1.5-fold higher genera from class Bacteroidia than the MF-fed piglets. In the large intestinal regions (cecum, PC, and rectum), MF diet alters microbiota composition, relative to HM diet, with sustained effects after weaning from the neonatal diet. These microbiota changes could impact immune system and health outcomes later in life.

Defining Dysbiosis for a Cluster of Chronic Diseases

The prevalence of many chronic diseases has increased over the last decades. It has been postulated that dysbiosis driven by environmental factors such as antibiotic use is shifting the microbiome in ways that increase inflammation and the onset of chronic disease. Dysbiosis can be defined through the loss or gain of bacteria that either promote health or disease, respectively. Here we use multiple independent datasets to determine the nature of dysbiosis for a cluster of chronic diseases that includes urinary stone disease (USD), obesity, diabetes, cardiovascular disease, and kidney disease, which often exist as co-morbidities. For all disease states, individuals exhibited a statistically significant association with antibiotics in the last year compared to healthy counterparts. There was also a statistically significant association between antibiotic use and gut microbiota composition. Furthermore, each disease state was associated with a loss of microbial diversity in the gut. Three genera, Bacteroides, Prevotella, and Ruminococcus, were the most common dysbiotic taxa in terms of being enriched or depleted in disease populations and was driven in part by the diversity of operational taxonomic units (OTUs) within these genera. Results of the cross-sectional analysis suggest that antibiotic-driven loss of microbial diversity may increase the risk for chronic disease. However, longitudinal studies are needed to confirm the causative effect of diversity loss for chronic disease risk.