Gut Bacterial Community Structure Research Articles

Early‐life gut bacterial community structure predicts disease risk and athletic performance in horses bred for racing

Early‐life gut bacterial community structure predicts disease risk and athletic performance in horses bred for racing

Early‐life gut bacterial community structure predicts disease risk and athletic performance in horses bred for racing

Early‐life gut bacterial community structure predicts disease risk and athletic performance in horses bred for racing

Impact of a Whole-Food, High-Soluble Fiber Diet on the Gut-Muscle Axis in Aged Mice.

Previous studies have identified a role for the gut microbiome and its metabolic products, short-chain fatty acids (SCFAs), in the maintenance of muscle mass and physical function (i.e., the gut-muscle axis), but interventions aimed at positively impacting the gut-muscle axis during aging are sparse. Gut bacteria ferment soluble fiber into SCFAs, and accordingly, to evaluate the impact of a high-soluble-fiber diet (HSFD) on the gut-muscle axis, we fed a whole-food, 3×-higher-soluble fiber-containing diet (relative to standard chow) to aged (98 weeks) C57BL/6J mice for 10 weeks. The HSFD significantly altered gut bacterial community structure and composition, but plasma SCFAs were not different, and a positive impact on muscle-related measures (when normalized to body weight) was not identified. However, when evaluating sex differences between dietary groups, female (but not male) HSFD-fed mice had significant increases for SCFAs, the quadriceps/body weight (BW) ratio, and treadmill work performance (distance run × BW), which suggests that an HSFD can positively impact the gut-muscle axis. In contrast, consistent effects in both male and female HSFD-fed mice included weight and fat loss, which suggests a positive role for an HSFD on the gut-adipose axis in aged mice.

Sucrose-based biofloc system promotes the enrichment of specific gut bacterial taxa to enhance disease suppression in shrimp (Penaeus vannamei)

Sucrose-based biofloc system could facilitate the growth and fitness of shrimp (Penaeus vannamei) by regulating the gut bacterial community. However, little is known about the specific taxa enriched by sucrose-based biofloc system that could improve shrimp health. Here, we investigated the influences of sucrose-based biofloc system on the diversity, structure, and function of the shrimp gut bacterial community. Sucrose-based biofloc system enhanced the observed species and shannon index of the gut bacterial community, and altered the bacterial community compositions by aggrandizing the relative abundances of Amaricoccus, Demequina, and Microbacterium, and decreasing the abundances of potential pathogens belonging to Mycoplasmataceae. The relative abundances of three key operational taxonomic units (OTUs), Demequina OTU465, Microbacterium OTU778, and Amaricoccus OTU 3213 accounted for >50% contributions to shrimp growth and survival rate. Sucrose-based biofloc system positively improved the bacterial community functions involved in amino acid metabolism, metabolism of terpenoids and polyketides, and carbohydrate metabolism. These improved functions were also positively associated with these key OTUs, further implying that they might be key for shrimp health. Finally, the corresponding strains of these key OTUs were isolated to construct a synthetic community, which showed significantly promotive role in shrimp growth and resistance against pathogen challenge. These results not only help us understand the role of sucrose-based biofloc system in improving shrimp fitness better but also provide a reference for suppressing disease occurrence through the use of bacterial inocula.

Novel herbal beverage ameliorates exercise-induced fatigue in mice by modulating oxidative stress and reshaping the gut microbiota

With the demands of enhancing exercise performance, dietary supplements are widely used in the health management of athletes and who engaged in strenuous exercise. Based on the list of edible and medicinal materials approved by China's National Health Commission, we composed an herbal beverage formula named SRB, initially identified its chemical composition, and clarified its preventive effect on exercise-induced fatigue (EIF). SRB supplementation for four weeks significantly enhanced exercise performance in mice, as reflected by exhaustive swimming test and treadmill exercise test. In mice that underwent one single exhaustive exercise, SRB supplementation markedly reduced metabolite accumulation, increased glycogen contents in the liver and muscle, promoted anti-oxidative enzyme activities, decreased hepatic malondialdehyde (MDA) level, and protected quadriceps femoris morphology, respectively. Anti-oxidative stress effect of SRB may be relevant with increased gene expressions of nuclear factor-erythroid 2-related factor 2 (Nrf2) and antioxidant response element (ARE)-dependent gene. Moreover, SRB treatment altered gut bacterial community structure, e.g., increased the relative abundance of short-chain fatty acids (SCFAs)-producing bacteria and decreased the relative abundance of sulfate-reducing bacteria. Altogether, we identified SRB as an effective anti-EIF dietary supplement with prebiotic effects in C57BL/6 mice.

Influence of phylogenetic, environmental, and behavioral factors on the gut bacterial community structure of dung beetles (Scarabaeidae: Scarabaeinae) in a Neotropical Biosphere Reserve.

Gut bacteria help dung beetles metabolize nutrients contained and synthesize those unavailable in their food, depending on the ecological scenario in which they develop. However, less is known about the influence of environmental and behavioral factors on the taxonomic composition of bacterial gut communities in Scarabaeinae beetles. To address this research topic, we analyzed 13 tropical dung beetle species in the Los Tuxtlas Biosphere Reserve, Mexico, to understand how the beetle tribe, habitat, food preference, food relocation, and parental care influence the composition of gut bacterial communities. We found that the beetle tribe is the primary factor impacting the taxonomic composition of gut bacterial communities. Among them, Deltochilini displayed the highest variability in diversity due to the different combinations of habitat and food preferences among its species. On the other hand, the other tribes studied did not exhibit such variable combinations. Habitat emerged as the second most influential factor, with forest-dwelling beetles displaying higher diversity. This can be attributed to the heterogeneous environments within tropical forests, which offer a greater diversity of food resources. In contrast, grassland beetles, living in more homogeneous environments and relying on cow feces as their main food source, exhibited lower diversity. Our findings suggest a correlation between bacterial diversity and food resource availability in complex habitats, such as tropical forests, which offer a wider array of food sources compared to simpler environments like grasslands.

Phylogenetic Constraints and Ecological Implications of Gut Bacterial Communities in Necrophagous Flies

This study examines the gut bacterial communities of four necrophagous fly species: Lucilia illustris, L. caesar, Chrysomya megacephala, and C. pinguis. The gut bacterial communities exhibited significant variation across species, showcasing a diverse range of bacterial phyla, classes, and genera. Each species harbored a unique set of bacteria, yet there was considerable overlap in taxa among species. Species richness was comparable across all species. However, measures that account for both richness and evenness, such as the Shannon diversity index and the inverse Simpson’s diversity index, indicated significant differences between species, especially between L. illustris and C. pinguis. The functional profiles of the gut bacterial communities mainly centered on metabolic and environmental information processing functions, with no marked differences between species. While this study had limitations in data collection, it still revealed a significant correlation between the phylogenetic distances of some fly species and the distances of their gut bacterial communities. This supports the hypothesis that the gut microbiota is not random but is influenced by the host’s evolutionary history or seasons. We confirmed that an association between phylogeny and gut bacterial community structure, as determined through entanglement analysis, exists. The study focused on only five individuals from the four fly species sampled during spring and summer, which might affect the generalizability of the results. Future research would benefit from replicating this study with a larger sample size across various seasons to ensure the more widespread applicability of the findings.

Factors shaping the gut microbiome of five species of lizards from different habitats.

Host-gut microbiota interactions are complex and can have a profound impact on the ecology and evolution of both counterparts. Several host traits such as systematics, diet and social behavior, and external factors such as prey availability and local environment are known to influence the composition and diversity of the gut microbiota. In this study, we investigate the influence of systematics, sex, host size, and locality/habitat on gut microbiota diversity in five lizard species from two different sites in Portugal: Podarcis bocagei and Podarcis lusitanicus, living in syntopy in a rural area in northern Portugal (Moledo); the invasive Podarcis siculus and the native Podarcis virescens, living in sympatry in an urbanized environment (Lisbon); and the invasive Teira dugesii also living in an urban area (Lisbon). We also infer the potential microbial transmission occurring between species living in sympatry and syntopy. To achieve these goals, we use a metabarcoding approach to characterize the bacterial communities from the cloaca of lizards, sequencing the V4 region of the 16S rRNA. Habitat/locality was an important factor explaining differences in gut bacterial composition and structure, with species from urbanized environments having higher bacterial diversity. Host systematics (i.e., species) influenced gut bacterial community structure only in lizards from the urbanized environment. We also detected a significant positive correlation between lizard size and gut bacterial alpha-diversity in the invasive species P. siculus, which could be due to its higher exploratory behavior. Moreover, estimates of bacterial transmission indicate that P. siculus may have acquired a high proportion of local microbiota after its introduction. These findings confirm that a diverse array of host and environmental factors can influence lizards' gut microbiota.

Prolonged darkness attenuates imidacloprid toxicity through the brain-gut-microbiome axis in zebrafish, Danio rerio

The present study investigated the toxic effects of IMI on brain and gut of zebrafish (Danio rerio) by a combination of transcriptome and microbiome analysis. In addition, the involvement of light/dark period was also evaluated. An acute toxic test was conducted on adult zebrafish weighing 0.45 ± 0.02 g with 4 experimental groups (n = 15): 1) IMI group (Light: Dark = 12: 12 h), 2) prolonged light group (Light: Dark = 20: 4 h), 3) prolonged darkness group (Light: Dark = 4: 20 h) which received 20 mg/L of IMI, and 4) control group, which was not treated with IMI (Light: Dark = 12: 12 h). The results showed that prolonged darkness improved the survival rate of zebrafish upon IMI exposure for 96 h. In the sub-chronic test, zebrafish were divided into the same 4 groups and exposed to IMI at 1 mg/L for 14 d (n = 30). The results showed that IMI induced oxidative stress in both IMI and prolonged light groups by inhibition of antioxidant activities and accumulation of oxidative products. Transcriptome analysis revealed a compromise of antioxidation and tryptophan metabolism pathways under IMI exposure. Several genes encoding rate-limiting enzymes in serotonin and melatonin synthesis were all inhibited in both IMI and LL groups. Meanwhile, significant decrease (P < 0.5) of serotonin and melatonin levels was observed. However, there's remarkable improvement of biochemical and transcriptional status in prolonged darkness group. In addition, microbiome analysis showed great alteration of gut bacterial community structure and inhibition of tryptophan metabolism pathway. Similarly, the gut microbiota dysbiosis induced by IMI was alleviated in prolonged darkness. In summary, sub-chronic IMI exposure induced neurotoxicity and gut toxicity in zebrafish by oxidative stress and impaired the brain-gut-axis through tryptophan metabolism perturbation. Prolonged darkness could effectively attenuate the IMI toxicity probably through maintaining a normal tryptophan metabolism.

Regulation of gut bacteria in silkworm (Bombyx mori) after exposure to endogenous cadmium-polluted mulberry leaves

Soil cadmium (Cd) pollution presents a severe pollution burden to flora and fauna due to its non-degradability and transferability. The Cd in the soil is stressing the silkworm (Bombyx mori) out through a soil-mulberry-silkworm system. The gut microbiota of B.mori are reported to shape host health. However, earlier research had not reported the effect of endogenous Cd-polluted mulberry leaves on the gut microbiota of B.mori. In the current research, we compared the phyllosphere bacteria of endogenous Cd-polluted mulberry leaves at different concentrations. The investigation of the gut bacteria of B.mori fed with the mulberry leaves was done to evaluate the impact of endogenous Cd- polluted mulberry leaves on the gut bacteria of the silkworm. The results revealed a dramatic change in the gut bacteria of B.mori whereas, the changes in the phyllosphere bacteria of mulberry leaves in response to an increased Cd concentration were insignificant. It also increased the α-diversity and altered the gut bacterial community structure of B. mori. A significant change in the abundance of dominant phyla of gut bacteria of B.mori was recorded. At the genus level, the abundance of Enterococcus, Brachybacterium and Brevibacterium group related to disease resistance, and the abundance of Sphingomonas, Glutamicibacter and Thermus related to metal detoxification was significantly increased after Cd exposure. Meanwhile, there was a significant decrease in the abundance of the pathogenic bacteria Serratia and Enterobacter. The results demonstrated that endogenous Cd-polluted mulberry leaves caused perturbations in the gut bacterial composition of B.mori, which may driven by Cd content rather than phyllosphere bacteria. A significant variation in the specific bacterial community indicated the adaptation of B. mori gut for its role in heavy metal detoxification and immune function regulation. The results of this study help to understand the bacterial community associated with endogenous Cd-polluted resistance in the gut of B.mori, which proves to be a novel addition in describing its response in activating the detoxification mechanism and promoting its growth and development. This research work will help to explore the other mechanisms and microbiota associated with the adaptations to mitigate the Cd pollution problems.

Mixed Tree Nuts, Cognition, and Gut Microbiota: A 4-Week, Placebo-Controlled, Randomized Crossover Trial in Healthy Nonelderly Adults

Beneficial effects of nut supplementation on cognitive function have previously been demonstrated in young and older adults. Alterations to gut microbiota have also been shown following tree nut consumption. However, no data exists on the effects of nuts on cognition and intestinal microbial communities assessed within the same study. The study aimed to examine the effects of daily consumption of tree nuts for 4 wk on cognitive function (primary outcome), mood, metabolomics, and gut microbial species (secondary outcomes) in healthy, nonelderly adults. This randomized, placebo-controlled, double-blind, counterbalanced crossover study assessed the effects of 4 wk of supplementation with 30 g/d mixed tree nuts versus placebo on cognition and mood in 79 healthy adults aged 18-49 y. Metabolic responses, gut bacterial community structure, and the potential for these to impact cognition were explored using a multi-omic approach. Bacterial community analysis was conducted in Quantitative Insights Into Microbial Ecology 2 (QIIME2). Mixed model analysis indicated that nut consumption led to significant improvements to accuracy (placebo M = 92.2% compared with NUTS M = 94.5%; P = 0.019) and speed of response (placebo M = 788 ms compared with NUTS M = 757 ms; P = 0.004) on a picture recognition task. No significant changes to bacterial community α or β diversity were observed when comparing nut consumption to the placebo arm. However, an unclassified Lachnospiraceae amplicon sequence variant (ASV) was significantly enriched in participants when supplemented with nuts (P = 0.015). No correlations were observed between the changes to picture recognition and the changes to the unclassified Lachnospiraceae ASV. There were no significant changes to the urinary metabolome. These findings indicate a positive effect of nut on cognition following only 4 wk of consumption in a healthy nonelderly sample, as well as upregulation of a microbial taxa associated with gut health. The effects appear to be independent of one another, but further exploration is required in those experiencing cognitive decline and/or gut dysbiosis.

The Gut Bacterial Community of Chlaenius pallipes (Coleoptera: Carabidae) Associates with Their Habitat and Morphology.

We investigated whether the gut bacterial community of Chlaenius pallipes could represent the health conditions of individuals or populations based on where these beetles inhabit. Considering the ecological traits of the species, the gut bacterial communities of carabid populations inhabiting stable or unstable habitats were compared. Food resource quality (δ15N) and morphological shape, especially body and wing size, may be significant factors that directly or indirectly affect the gut bacterial community of carabid beetles. Firmicutes (51.7%) and Proteobacteria (36.3%) were the predominant phyla in the gut bacterial community of C. pallipes. A significant difference in the gut bacterial community structure was observed between organisms inhabiting unstable and stable habitats in this study. Wing size, as estimated by centroid size, was correlated with differences in the gut bacterial community composition of the species. Even if a factor is not strong enough to determine the survival of carabid beetles, the composition of the gut bacterial community can change. We found that although each individual has a large variation in the gut bacterial community composition, the gut bacterial community can be used to evaluate the condition of each habitat through consistent investigation. Habitat assessment based on changes in the number of carabid beetle species and their composition requires relatively long-term research; however, the gut bacterial community of carabid beetles can help identify short-term environmental changes.

Comparison of Gut Bacterial Communities of Locusta migratoria manilensis (Meyen) Reared on Different Food Plants.

Simple SummaryAlthough locusts can cause major agricultural damage, they also constitute a valuable food resource. At present, L. migratoria manilensis has been largely domesticated, being considered an edible insect in China. Feeding variety is one of the main characteristics of L. migratoria manilensis. There are apparent differences in the capacity of locusts to adapt to different food plants. To elucidate the effect of different food plants (i.e., goosegrass, maize leaves, soybean leaves, and pakchoi) on the growth and development of L. migratoria manilensis, the gut bacterial community composition of L. migratoria manilensis fifth instars fed on different plants was analyzed by high-throughput sequencing. Gut bacterial communities were affected by food plants and may play an essential role in host adaption. Feeding on different food plants has significant effects on the growth and development of L. migratoria manilensis. The present study establishes a theoretical foundation for studying the interplay between gut bacteria structure and L. migratoria manilensis adaptation.Locusts, in particular Locusta migratoria manilensis (Meyen), have been associated with major damages in agriculture, forestry, and animal husbandry in China. At present, L. migratoria manilensis has been largely domesticated, being considered an edible insect in China. Feeding variety is one of the main characteristics of L. migratoria manilensis. It has been demonstrated that microorganisms inhabiting the insect gut impact nutrition, development, defense, and reproduction of the insect host. The aim of the present study was to search for the adaptation mechanism of L. migratoria manilensis feeding on four different food plants (goosegrass, maize leaves, soybean leaves, and pakchoi) and explore changes in the gut bacterial community structure of the insect at the fifth instar nymph stage. Proteobacteria and Firmicutes were the dominant phyla, whereas Kluyvera, Enterobacter, Pseudocitrobacter, Klebsiella, Cronobacter, Citrobacter, Lactococcus, and Weissella were the dominant genera in the gut of L. migratoria manilensis. Principal component analysis and permutational multivariate analysis of variance (PERMANOVA) revealed significant differences in the gut microbiota structure of L. migratoria manilensis fed on different food plants. Moreover, functional prediction analysis revealed that metabolic and cellular processes were the most enriched categories. Within the category of metabolic processes, the most enriched pathways were carbohydrate transport and metabolism; amino acid transport and metabolism; translation, ribosomal structure, and biogenesis; cell wall/membrane/envelope biogenesis; inorganic ion transport and metabolism; and energy production and conversion. Collectively, the present results revealed that the structure of gut bacterial communities in L. migratoria manilensis fed on different food plants is impacted by food plants, which may play an essential part in the adaptation of the host.

Gut Microbiome and Metabolome Modulation by Maternal High-Fat Diet and Thermogenic Challenge.

The gut microbiota plays a critical role in energy homeostasis and its dysbiosis is associated with obesity. Maternal high-fat diet (HFD) and β-adrenergic stimuli alter the gut microbiota independently; however, their collective regulation is not clear. To investigate the combined effect of these factors on offspring microbiota, 20-week-old offspring from control diet (17% fat)- or HFD (45% fat)-fed dams received an injection of either vehicle or β3-adrenergic agonist CL316,243 (CL) for 7 days and then cecal contents were collected for bacterial community profiling. In a follow-up study, a separate group of mice were exposed to either 8 °C or 30 °C temperature for 7 days and blood serum and cecal contents were used for metabolome profiling. Both maternal diet and CL modulated the gut bacterial community structure and predicted functional profiles. Particularly, maternal HFD and CL increased the Firmicutes/Bacteroidetes ratio. In mice exposed to different temperatures, the metabolome profiles clustered by treatment in both the cecum and serum. Identified metabolites were enriched in sphingolipid and amino acid metabolism in the cecum and in lipid and energy metabolism in the serum. In summary, maternal HFD altered offspring’s response to CL and altered microbial composition and function. An independent experiment supported the effect of thermogenic challenge on the bacterial function through metabolome change.

Gut Bacterial Diversity and Community Structure of Spodoptera exigua (Lepidoptera: Noctuidae) in the Welsh Onion-producing Areas of North China.

Gut microbiota play an important role in digestion, development, nutritional metabolism, and detoxification in insects. However, scant information exists on the gut bacterial variation, composition, and community structure of the beet armyworm, Spodoptera exigua (Hübner), and how its gut microbiota has adapted to different geographical environments. Using 16S rRNA high-throughput sequencing technology, we detected 3,837,408 high-quality reads and 1,457 operational taxonomic units (OTUs) in 47 gut samples of S. exigua collected from ten sites in northern China. Overall, we identified 697 bacterial genera from 30 phyla, among which Proteobacteria and Firmicutes were the most dominant phyla. Gut bacterial alpha-diversity metrics revealed significant differences among these populations. We detected the highest alpha bacterial diversity in Xinming, northern Liaoning Province, and the lowest bacterial diversity in Zhangwu, western Liaoning Province. Beta diversity indicated that the gut microbial community structure of S. exigua in Liaoning Province was significantly different from that of other populations. There was a similar microbial community structure among populations in the adjacent province, suggesting that the environment influences bacterial succession in this pest. Finally, PICRUSt analysis demonstrated that microbial functions closely associated with the gut microbiomes mainly included membrane transport, carbohydrate metabolism and replication, and amino acid metabolism.

Effects of Dietary Antimicrobial Growth Promoters on Performance Parameters and Abundance and Diversity of Broiler Chicken Gut Microbiome and Selection of Antibiotic Resistance Genes.

Antimicrobial growth promoters (AGPs) are commonly used in broiler production. There is a huge societal concern around their use and their contribution to the proliferation of antimicrobial resistance (AMR) in food-producing animals and dissemination to humans or the environment. However, there is a paucity of comprehensive experimental data on their impact on poultry production and the AMR resistome. Here, we investigated the effect of five antimicrobial growth promoters (virginiamycin, chlortetracycline, bacitracin methyl disalicylate, lincomycin, and tylosin) used in the commercial broiler production in the Indian subcontinent and in the different parts of the world for three consecutive production cycles on performance variables and also the impact on gut bacteria, bacteriophage, and resistome profile using culture-independent approaches. There was no significant effect of AGPs on the cumulative growth or feed efficiency parameters at the end of the production cycles and cumulative mortality rates were also similar across groups. Many antibiotic resistance genes (ARGs) were ubiquitous in the chicken gut irrespective of AGP supplementation. In total, 62 ARGs from 15 antimicrobial classes were detected. Supplementation of AGPs influenced the selection of several classes of ARGs; however, this was not correlated necessarily with genes relevant to the AGP drug class; some AGPs favored the selection of ARGs related to antimicrobials not structurally related to the AGP. AGPs did not impact the gut bacterial community structure, including alpha or beta diversity significantly, with only 16–20 operational taxonomic units (OTUs) of bacteria being altered significantly. However, several AGPs significantly reduced the population density of some of the potential pathogenic genera of bacteria, such as Escherichia coli. Chlortetracycline increased the abundance of Escherichia phage, whereas other AGPs did not influence the abundance of bacteriophage significantly. Considering the evidence that AGPs used in poultry production can select for resistance to more than one class of antimicrobial resistance, and the fact that their effect on performance is not significant, their use needs to be reduced and there is a need to monitor the spread of ARGs in broiler chicken farms.

A meta-analysis study of the robustness and universality of gut microbiota-shrimp diseases relationship.

Intensive case study has established dysbiosis in the gut microbiota-shrimp disease relationship; however, variability in experimental design and the diversity of diseases arise the question of whether some gut indicators are robust and universal in response to shrimp health status, irrespective of causal agents. Through an unbiased subject-level meta-analysis framework, we re-analysed 10 studies, including 261 samples, four lifestages and six different diseases (the causal agents are virus, bacterial, eukaryotic pathogens, or unknown). Results showed that shrimp diseases reproducibly altered the structure of gut bacterial community, but not diversity. After ruling out the lifestage- and disease specific- discriminatory taxa (different diseases dependent indicators), we identify 18 common disease-discriminatory taxa (indicative of health status, irrespective of causal agents) that accurately diagnosed (90.0% accuracy) shrimp health status, regardless of different diseases. These optimizations substantially improved the performance (62.6% vs. 90.0%) diagnosing model. The robustness and universality of model were validated for effectiveness via leave-one-dataset-out validation and independent cohorts. Interspecies interaction and stability of the gut microbiotas were consistently compromised in diseased shrimp compared with corresponding healthy cohorts, while stochasticity and beta-dispersion exhibited the opposite trend. Collectively, our findings exemplify the utility of microbiome meta-analyses in identifying robust and reproducible features for quantitatively diagnosing disease incidence, and the downstream consequences for shrimp pathogenesis from an ecological prospective.

Bacterial Atlas of Mouse Gut Microbiota

Background. Mouse model is one of the most widely used animal models for exploring the roles of human gut microbiota, a complex system involving in human immunity and metabolism. However, the structure of mouse gut bacterial community has not been explored at a large scale. To address this concern, the diversity and composition of the gut bacteria of 600 mice were characterized in this study. Results. The results showed that the bacteria belonging to 8 genera were found in the gut microbiota of all mouse individuals, indicating that the 8 bacteria were the core bacteria of mouse gut microbiota. The dominant genera of the mouse gut bacteria contained 15 bacterial genera. It was found that the bacteria in the gut microbiota were mainly involved in host’s metabolisms via the collaborations between the gut bacteria. The further analysis demonstrated that the composition of mouse gut microbiota was similar to that of human gut microbiota. Conclusion. Our study presented a bacterial atlas of mouse gut microbiota, providing a solid basis for investing the bacterial communities of mouse gut microbiota.

Effects of Host Plants on Bacterial Community Structure in Larvae Midgut of Spodoptera frugiperda.

Simple SummaryThe gut microbiota plays an important role in insect physiology and behavior. The interaction among the different structures of gut bacterial community in the fall armyworm (FAW), Spodoptera frugiperda, and different host plants, and whether these different gut bacteria are responsible for the rapid spread of FAW to a variety of host plants after invasion are largely unexplored. In the present paper, we used a culture-independent approach targeting the bacterial 16S rRNA gene of gut bacteria of the 5th instar larvae of FAW fed on four different host plants. It aimed to analyze the effects of host plants on gut bacteria abundance, community structure and metabolic function. We found that host plants exerted considerable effects on the structure and composition of the gut bacteria in FAW and the differences among the four groups identified were significant. They were related to the detoxification and adaptation of FAW to toxic secondary metabolites of the host plant. These differences enabled the gut microbiome to perform different functions. This study lays a foundation for further studies on the function of intestinal bacteria in FAW and the adaptive mechanism to the host.The fall armyworm (FAW), Spodoptera frugiperda, is one of the most important invasive species and causes great damage to various host crops in China. In this study, the diversity and function of gut bacteria in the 5th instar larvae of FAW fed on maize, wheat, potato and tobacco leaves were analyzed through 16S rRNA sequencing. A total of 1324.25 ± 199.73, 1313.5 ± 74.87, 1873.00 ± 190.66 and 1435.25 ± 139.87 operational taxonomic units (OTUs) from the gut of FAW fed on these four different host plants were detected, respectively. Firmicutes, Proteobacteria and Bacteroidetes were the most abundant bacterial phyla. Beta diversity analysis showed that the gut bacterial community structure of larvae fed on different host plants was significantly differentiated. At the genus level, the abundance of Enterococcus in larvae fed on wheat was significantly lower than those fed on the other three host plants. Enterobacter and ZOR0006 were dominant in FAW fed on tobacco leaves, and in low abundance in larvae fed on wheat. Interestingly, when fed on Solanaceae (tobacco and potato) leaves which contained relative higher levels of toxic secondary metabolites than Gramineae (wheat and maize), the genera Enterococcus, Enterobacter and Acinetobacter were significantly enriched. The results indicated that gut bacteria were related to the detoxification and adaptation of toxic secondary metabolites of host plants in FAW. Further analysis showed that replication, repair and nucleotide metabolism functions were enriched in the gut bacteria of larvae fed on tobacco and potato. In conclusion, the gut bacterial diversity and community composition in FAW larvae fed on different host plants showed significant differences, and the insect is likely to regulate their gut bacteria for adaptation to different host plants.

Shift and interaction of intestinal bacterial community in juvenile Chinese mitten crab Eriocheir sinensis upon astaxanthin feeding

Intestinal bacterial communities of juvenile Chinese mitten crab Eriocheir sinensis are investigated for the effects of dietary supplementation with different amounts of micro-algal astaxanthin (0, 30, 60, 90, and 120 mg/kg dry diet) and for the correlation to crab hemolymph antioxidant capacity and immunity. Comprehensively analyzing of bacterial 16S rRNA gene amplicons showed that astaxanthin supplement, particularly of 90 mg/kg, appeared to enrich especially the number of Bacteroidetes members, albeit not significantly, increased the relative abundance of Dysgonomonas sp. (OTU1156), and significantly decreased the relative abundance of Jinshanibacter sp. (OTU1324) (P < 0.05). Both Dysgonomonas sp. (OTU1156) and Jinshanibacter sp. (OTU1324) are dominant and native bacterial lineages, present in neither the farming water nor feed. The Dysgonomonas sp. (OTU1156) are probably probiotics involving the digesting of food rich in plant matter, while the Jinshanibacter sp. (OTU1324) are potential parasitic/pathogenic bacteria. Intestinal bacterial communities were improved for the metabolic capacity by astaxanthin, such as the ability to digest xenobiotics, which significantly correlates with the total antioxidant capacity (P < 0.05) of crab hemolymph. These findings contribute to better understanding of the mutual-interaction among astaxanthin, gut bacterial community structure, and hemolymph antioxidant capability and immunity, and shed light on the health and disease-resistance aquaculture of crabs.