Metagenomic assessment of the Cebus apella gut microbiota

Cebus Apella (C. apella) is a species of Nonhuman Primate (NHP) used for biomedical research because it is phylogenetically similar and shares anatomical commonalities with humans. Here, the gut microbiota of three C. apella were examined in the different regions of the intestinal tract. Using metagenomics, the gut microbiota associated with the luminal content and mucus layer for each intestinal region was identified, and functionality was investigated by quantifying the levels of short chain fatty acids (SCFAs) produced. The results of this study show a high degree of similarity in the intestinal communities among C. apella subjects, with multiple shared characteristics. First, the communities in the lumen were more phylogenetically diverse and rich compared to the mucus layer communities throughout the entire intestinal tract. The small intestine communities in the lumen displayed a higher Shannon diversity index compared to the colon communities. Second, all the communities were dominated by aero‐tolerant taxa such as Streptococcus, Enterococcus, Abiotrophia, and Lactobacillus, although there was preferential colonization of specific taxa observed. Finally, the primary SCFA produced throughout the intestinal tract was acetic acid, with some propionic acid and butyric acid detected in the colon regions. The small intestine microbiota produced significantly less SCFAs compared to the communities in the colon. Collectively, these data provide an in‐depth report on the composition, distribution, and SCFA production of the gut microbiota along the intestinal tract of the C. apella NHP animal model.     

肠道微生物资源库的构建：进展、方法和展望

基于肠道微生物组的活体药物(live biotherapeutics, LBPs)开发、菌株与宿主互作的分子机制研究及新型抗菌肽、酶、代谢途径的挖掘使得肠道微生物资源库的构建成为必然。本文对近年来国内外不同研究团队肠道微生物资源库构建进行系统比较,分析了不同构建方法间的差异,以期为国内外不同研究者在构建和丰富现有肠道微生物资源库方面提供帮助。目前,肠道微生物资源库共有1 000多种肠道细菌,分属于12个门、22个纲、39个目、96个科和358个属,厚壁菌门(Firmicutes)、变形菌门(Proteobacteria)、拟杆菌门(Bacteroidota)、放线菌门(Actinomycetota)菌株最多。测序结果显示人肠道细菌物种丰富度在2 000左右,因此目前分离到的菌株远未达到饱和。在构建方法上,一般对粪便样本进行或不进行乙醇处理,使用非选择性培养基(以Gifu厌氧培养基为代表)进行涂布分离培养,最后进行纯化培养。使用较为简单的培养方法即可培养得到多数常见的重要肠道微生物类目,如双歧-乳杆菌属(Lactobacillus-bifidobacteria)菌株、阿克曼氏菌(Akkermansia muciniphila)、普拉梭菌(Faecalibacterium prausnitzii)、普雷沃氏菌属(Prevotella)及S24-7科菌株等。为满足功能研究和产品开发的需要,肠道微生物菌种资源库的样本来源应该进一步覆盖更多地域和生活习惯、疾病及健康状态具有显著差异的人群,从而进一步丰富肠道关键物种的菌株多样性。     

Akkermansia muciniphila alleviates high-fat-diet-related metabolic-associated fatty liver disease by modulating gut microbiota and bile acids

It has been reported that Akkermansia muciniphila improves host metabolism and reduces inflammation; however, its potential effects on bile acid metabolism and metabolic patterns in metabolic-associated fatty liver disease (MAFLD) are unknown. In this study, we have analysed C57BL/6 mice under three feeding conditions: (i) a low-fat diet group (LP), (ii) a high-fat diet group (HP) and (iii) a high-fat diet group supplemented with A. muciniphila (HA). The results found that A. muciniphila administration relieved weight gain, hepatic steatosis and liver injury induced by the high-fat diet. A. muciniphila altered the gut microbiota with a decrease in Alistipes, Lactobacilli, Tyzzerella, Butyricimonas and Blautia, and an enrichment of Ruminiclostridium, Osclibacter, Allobaculum, Anaeroplasma and Rikenella. The gut microbiota changes correlated significantly with bile acids. Meanwhile, A. muciniphila also improved glucose tolerance, gut barriers and adipokines dysbiosis. Akkermansia muciniphila regulated the intestinal FXR-FGF15 axis and reshaped the construction of bile acids, with reduced secondary bile acids in the caecum and liver, including DCA and LCA. These findings provide new insights into the relationships between probiotics, microflora and metabolic disorders, highlighting the potential role of A. muciniphila in the management of MAFLD.     

百里酚和香芹酚改变肠道微生物组成抑制羔羊腹泻的作用研究

【目的】本试验研究百里酚和香芹酚对滩羊羔羊腹泻、肠道短链脂肪酸和微生物组成的影响,旨在为利用植物提取物手段治疗羔羊腹泻提供可用的添加剂和理论基础。【方法】本研究选择腹泻发病时间为2-3 d的10只腹泻羔羊,随机分为2组,分为腹泻羔羊组(CON组)和百里酚和香芹酚处理组(SCAT组),试验期间SCAT组羔羊补充200 mg/只/d的百里酚和香芹酚1:1混合品,处理时间为7 d。【结果】百里酚和香芹酚处理能够显著提高腹泻羔羊日增重,降低羔羊腹泻指数和腹泻率(P<0.05),降低血清促炎因子表达水平(P<0.05),提高肠道短链脂肪酸(short-chain fatty acids,SCFA)丁酸浓度(P<0.05);同时百里酚和香芹酚能够改变腹泻羔羊肠道微生物组成,提高肠道中双歧杆菌(Bifidobacteriaceae)和阿克曼氏菌(Akkermansiaceae)的相对丰度,降低肠杆菌科(Enterobacteriaceae)相关菌的相对丰度。【结论】百里酚和香芹酚能够提高肠道有益菌相对丰度和有益代谢物丁酸的浓度,降低致病菌相对丰度,从而有效抑制羔羊腹泻,可作为新型替...     

分娩方式对北京地区持续母乳喂养的34周龄婴儿肠道菌群影响

[目的] 比较持续母乳喂养条件下不同分娩方式的34周龄婴儿肠道菌群差异,探讨分娩方式对较大婴儿肠道菌群发育的影响。[方法] 在北京地区招募健康足月分娩母乳喂养婴儿,在34周仍然参与随访的持续母乳喂养婴儿共21例,其中剖宫产婴儿16例、阴道分娩婴儿5例,进行肠道菌群的16S rRNA检测。[结果] 两组共21个粪便样本中,共注释到6个门,分别为：疣微菌门、变形菌门、梭杆菌门、厚壁菌门、放线菌门和拟杆菌门;两组共21个样本中共有57个OTU注释到属水平,其中,26个属水平OTU被注释到厚壁菌门,18个属水平OTU被注释到变形菌门,6个属水平OTU被注释到放线菌门,5个属水平OTU被注释到拟杆菌门,梭杆菌门、疣微菌门各有1个属水平OTU被注释。其中变形菌门在阴道分娩组（44.17%）肠道菌群中的含量高于剖宫产组（16.10%）;而放线菌门在阴道分娩婴儿（0.00%）肠道菌群中的含量低于剖宫产婴儿（0.09%）。阴道分娩组与剖宫产组相比,共有7个菌属的丰度发生了显著降低（P<0.05）,分别为副杆菌属、葡萄球菌属、嗜血杆菌属、乳杆菌属、肠球菌属、双歧杆菌属及一注释到科水平的毛螺旋菌科OTU。[结论] 分娩方式对持续母乳喂养的婴儿肠道菌群结构存在影响,且这种影响在出生后34周仍然存在。     

(S)-雌马酚对肠道菌群的体外调控作用及其可代谢性研究

[目的]研究(S)-雌马酚对人体肠道菌群的体外调控作用和人体肠道菌群对(S)-雌马酚的代谢衍生作用。[方法]采用人体肠道菌群体外批量发酵、细菌16S rRNA基因高通量测序、气相色谱、液相色谱和质谱等检测(S)-雌马酚与人体肠道菌群体外相互作用。[结果]体外添加(S)-雌马酚对总体人肠道菌群结构和短链脂肪酸产量影响不明显。添加0.45 mmol/L (S)-雌马酚组与对照组相比,未检测到相对丰度发生显著变化的细菌;添加0.90 mmol/L (S)-雌马酚组与对照组相比,显著增加了肠杆菌科(Enterobacteriaceae)等条件致病菌的相对丰度,减少了潜在益生菌粪球菌属(Coprococcus)的比例。代谢分析发现,发酵培养液中(S)-雌马酚的浓度降低了约15%−30%,推测可能被微生物进一步降解或衍生修饰。[结论]从体外调控肠道菌群的角度判断,0.45 mmol/L (S)-雌马酚相对较安全,而0.90 mmol/L (S)-雌马酚可能会破坏肠道菌群平衡。(S)-雌马酚可以被人体肠道菌群进一步代谢,其特定代谢产物的结构与功能及其体内生物安全性有待进一步研究。     

Age-dependent changes in the gut microbiota and serum metabolome correlate with renal function and human aging

Human aging is invariably accompanied by a decline in renal function, a process potentially exacerbated by uremic toxins originating from gut microbes. Based on a registered household Chinese Guangxi longevity cohort (n = 151), we conducted comprehensive profiling of the gut microbiota and serum metabolome of individuals from 22 to 111 years of age and validated the findings in two independent East Asian aging cohorts (Japan aging cohort n = 330, Yunnan aging cohort n = 80), identifying unique age-dependent differences in the microbiota and serum metabolome. We discovered that the influence of the gut microbiota on serum metabolites intensifies with advancing age. Furthermore, mediation analyses unveiled putative causal relationships between the gut microbiota (Escherichia coli, Odoribacter splanchnicus, and Desulfovibrio piger) and serum metabolite markers related to impaired renal function (p-cresol, N-phenylacetylglutamine, 2-oxindole, and 4-aminohippuric acid) and aging. The fecal microbiota transplantation experiment demonstrated that the feces of elderly individuals could influence markers related to impaired renal function in the serum. Our findings reveal novel links between age-dependent alterations in the gut microbiota and serum metabolite markers of impaired renal function, providing novel insights into the effects of microbiota-metabolite interplay on renal function and healthy aging.     

Val-Val-Tyr-Pro protects against non-alcoholic steatohepatitis in mice by modulating the gut microbiota and gut-liver axis activation

Val-Val-Tyr-Pro (VVYP) peptide is one of the main active components of Globin digest (GD). Our previous studies indicated that VVYP could protect against acetaminophen and carbon tetrachloride-induced acute liver failure in mice and decrease blood lipid level. However, the effects and underlying mechanisms of VVYP in the treatment of non-alcoholic steatohepatitis (NASH) have not been discovered. Our present study was designed to investigate the preventive effect of VVYP on NASH and its underlying specific mechanisms. We found that VVYP inhibited the cytotoxicity and lipid accumulation in L-02 cells that were exposed to a mixture of free fatty acid (FFA). VVYP effectively alleviated the liver injury induced by methionine-choline-deficient (MCD) diet, demonstrated by reducing the levels of serum alanine aminotransferase (ALT)/aspartate aminotransferase (AST)/triglycerides (TG)/non-esterified fatty acids (NEFA) and improving liver histology. VVYP decreased expression levels of lipid synthesis-related genes and reduced levels of the proinflammation cytokines in the liver of mice fed by MCD diet. Moreover, VVYP inhibited the increased level of LPS and reversed the liver mitochondria dysfunction induced by MCD diet. Meanwhile, VVYP significantly increased the abundance of beneficial bacteria such as Eubacteriaceae, coriobacteriacease, Desulfovibrionaceae, S24-7 and Bacteroidia in high-fat diet (HFD)-fed mice, however, VVYP reduced the abundance of Lactobacillus. Moreover, VVYP conferred the protective effect of intestinal barrier via promoting the expression of the mucins and tight junction (TJ)-associated genes and inhibited subsequent liver inflammatory responses. These results indicated that the protective role of VVYP on NASH is mediated by modulating gut microbiota imbalance and related gut-liver axis activation. VVYP might be a promising drug candidate for NASH.     

Gut morphology,feeding rate and gut clearance in five species of caddis larvae

Feeding rate, the rate of movement of food through the gut and gut morphology of large larvae of five caddis species (Halesus radiatus, Hydropsyche instabilis, Polycentropus kingi, Rhyacophila dorsalis and Potamophylax cingulatus) were investigated in the laboratory. Following 72 hr starvation, P. cingulatus and H. radiatus larvae became satiated (refused prey offered directly to the mouthparts) after consuming 8–11 and 9–13 mayfly nymphs (Baetis rhodani, 3.5–4.6 mm) respectively. Hunger level affected prey consumption. In P. cingulatus, the number of prey consumed over 24 h (at 9.5–12 °C) increased with starvation periods from 0–72 h, but declined following longer starvation periods. Six clearly recognisable gut states (defined by the position of food material in various parts of the gut) can be identified at different times since commencement of a meal. As environmental temperature increased (from 8–12 °C to 15–17 °C), the rate of change of the gut state increased and the food retention time decreased in all species. Feeding periodicity (i.e. nocturnal/diurnal activity) in the field was estimated based on the evacuation rate and the gut state and environmental temperature at the known time of collection. Initiation of consumption of prey appeared to coincide with emptying of the foregut and proximal midgut, whereas actual feeding continued until complete satiation when some threshold fullness of the foregut had been reached. The length of time food was held in the foregut was positively correlated with increasing specialisation of the foregut (particularly elaboration of the proventriculus).     

Spirulina platensis alleviates chronic inflammation with modulation of gut microbiota and intestinal permeability in rats fed a high‐fat diet

Recent research suggested that taking a high‐fat diet (HFD) may lead to a gut microbiota imbalance and colon tissue damage. This would lead to increased intestinal permeability and consequent constant circulation of low‐grade inflammatory cytokines. Spirulina platensis can protect against HFD‐induced metabolic inflammation and can stimulate the growth of beneficial bacteria in in vitro stool cultures. However, it is unknown whether this beneficial effect acts on intestinal tissues. In this study, rats were fed a high‐fat diet fed with 3% S platensis for 14 weeks. We analysed endotoxin, the composition of the microbiota, inflammation and gut permeability. We found that S platensis decreased the bodyweight and visceral fat pads weight of the HFD‐fed rats. In addition, it lowered the levels of lipopolysaccharide and pro‐inflammatory cytokines in serum. Our results showed that S platensis could largely reduce the relative amount of Proteobacteria and the Firmicutes/Bacteroidetes ratio in faecal samples from HFD‐fed rats. S platensis significantly reduced intestinal inflammation, as shown by decreased expression of myeloid differentiation factor 88 (MyD88), toll‐like receptor 4 (TLR4), NF‐κB (p65) and inflammatory cytokines. S platensis also ameliorated the increased permeability and decreased expression of tight junction proteins in the intestinal mucosa, such as ZO‐1, Occludin and Claudin‐1. Therefore, in HFD‐induced gut dysbiosis rats, S platensis benefits health by inhibiting chronic inflammation and gut dysbiosis, and modulating gut permeability.     

银杏双黄酮和银杏内酯B与人体肠道菌群体外互作研究

[目的]银杏提取物在防治心血管系统和神经系统疾病方面发挥重要功能.鉴于肠道菌群已被认定为一个新兴的药物作用靶标,研究银杏双黄酮和银杏内酯与人体肠道菌群之间的相互作用具有非常重要的意义,这将为进一步理解银杏提取物的功能和作用机制奠定基础.[方法]本研究使用人体肠道菌群体外批量发酵、细菌总量测定、细菌16S rDNA高通量...     

The cotton stainer's gut microbiota suppresses infection of a cotransmitted trypanosomatid parasite

The evolutionary and ecological success of many insects is attributed to mutualistic partnerships with bacteria that confer hosts with novel traits including food digestion, nutrient supplementation, detoxification of harmful compounds and defence against natural enemies. Dysdercus fasciatus firebugs (Hemiptera: Pyrrhocoridae), commonly known as cotton stainers, possess a simple but distinctive gut bacterial community including B vitamin‐supplementing Coriobacteriaceae symbionts. In addition, their guts are often infested with the intestinal trypanosomatid parasite Leptomonas pyrrhocoris (Kinetoplastida: Trypanosomatidae). In this study, using experimental bioassays and fluorescence in situ hybridization (FISH), we report on the protective role of the D. fasciatus gut bacteria against L. pyrrhocoris. We artificially infected 2nd instars of dysbiotic and symbiotic insects with a parasite culture and measured parasite titres, developmental time and survival rates. Our results show that L. pyrrhocoris infection increases developmental time and slightly modifies the quantitative composition of the gut microbiota. More importantly, we found significantly higher parasite titres and a tendency towards lower survival rates in parasite‐infected dysbiotic insects compared to symbiotic controls, indicating that the gut bacteria successfully interfere with the establishment or proliferation of L. pyrrhocoris. The colonization of symbiotic bacteria on the peritrophic matrix along the gut wall, as revealed by FISH, likely acts as a barrier blocking parasite attachment or entry into the hemolymph. Our findings show that in addition to being nutritionally important, D. fasciatus’ gut bacteria complement the host's immune system in preventing parasite invasions and that a stable gut microbial community is integral for the host's health.     

Balancing reactive oxygen species generation by rebooting gut microbiota

Reactive oxygen species (ROS; free radical form O₂^•−, superoxide radical; OH^•, hydroxyl radical; ROO^•, peroxyl; RO^•, alkoxyl and non-radical form ¹O₂, singlet oxygen; H₂O₂, hydrogen peroxide) are inevitable companions of aerobic life with crucial role in gut health. But, overwhelming production of ROS can cause serious damage to biomolecules. In this review, we have discussed several sources of ROS production that can be beneficial or dangerous to the human gut. Micro-organisms, organelles and enzymes play crucial role in ROS generation, where NOX1 is the main intestinal enzyme, which produce ROS in the intestine epithelial cells. Previous studies have reported that probiotics play significant role in gut homeostasis by checking the ROS generation, maintaining the antioxidant level, immune system and barrier protection. With current knowledge, we have critically analysed the available literature and presented the outcome in the form of bubble maps to suggest that the probiotics help in controlling the ROS-specific intestinal diseases, such as inflammatory bowel disease (IBD) and colon cancer. Finally, it has been concluded that rebooting of the gut microbiota with probiotics, postbiotics or faecal microbiota transplantation (FMT) can have crucial implications in the structuring of gut communities for the personalized management of the gastrointestinal (GI) diseases.     

Pediococcus pentosaceus LI05 alleviates DSS-induced colitis by modulating immunological profiles,the gut microbiota and short-chain fatty acid levels in a mouse model

The gut microbiota is considered a key factor in pathogenesis and progression of inflammatory bowel disease (IBD). The bacterium Pediococcus pentosaceus LI05 alleviated host inflammation by maintaining the gut epithelial integrity, modulating the host immunity, gut microbiota and metabolism, but its effect on IBD remains unclear. The present study aimed to investigate the role and mechanisms of P. pentosaceus LI05. Mice were administered P. pentosaceus LI05 or phosphate-buffered saline once daily by oral gavage for 14 days, and colitis was induced by providing mice 2% DSS-containing drinking water for 7 days. P. pentosaceus LI05 ameliorated colitis in mice and reduced the body weight loss, disease activity index (DAI) scores, colon length shortening, intestinal permeability and the proinflammatory cytokine levels. Furthermore, a significantly altered gut microbiota composition with increased diversity and short-chain fatty acid (SCFA) production was observed in mice treated with P. pentosaceus LI05. Several genera, including Akkermansia and Faecalibacterium, were differentially enriched in the P. pentosaceus LI05-treated mice and were negatively correlated with colitis indices and positively correlated with gut barrier markers and SCFA levels. The P. pentosaceus LI05 treatment alleviated intestinal inflammation by maintaining the intestinal epithelial integrity and modulating the immunological profiles, gut microbiome and metabolite composition. Based on our findings, P. pentosaceus LI05 might be applied as potential preparation to ameliorate colitis.     

Age-related differences in gut microbial community composition of captive spotted seals (Phoca largha)

Age is an important factor that significantly impacts the gut microbiota of various mammals. Captive spotted seals (Phoca largha) provide an ideal opportunity to study how age affects their gut microbiota, excluding other environmental factors, which is a challenge when monitoring wildlife. Here, the bacterial composition of the feces of captive spotted seals from four age groups were analyzed; namely, pup (<1 year old), juvenile (1–2 years old), subadult (2–3 years old), and adult (≥4 years old). Firmicutes were the dominant bacteria in all measured feces; however, the composition of gut microbiota in seals of different ages was distinct. Blautia, Slackia, and an unclassified Peptostreptococcaceae were more abundant in pups; Clostridium was abundant in juveniles; Fusobacterium, Bacteroides, and Psychrobacter were abundant in subadults; and Dorea and Peptostreptococcus abundant in adults. Two and 4 years of age appeared to be the most influential time nodes for variation in gut microbiota. In conclusion, this study identified age-related differences in the composition of gut microbiota in P. largha.     

强化玉米饮食对小鼠肠道菌群结构和功能的影响

【目的】采用高通量测序方法研究强化玉米饮食对小鼠肠道菌群结构的影响以及可提高宿主糖代谢相关菌群功能基因的分析。【方法】分别给予两组小鼠(各10只)常规饮食和强化玉米饮食(1/4的玉米粉加3/4的常规饮食成分),喂养10周,之后采集小鼠粪便样本,提取DNA,使用高通量测序仪进行宏基因组测序分析,比较两组小鼠肠道菌群和功能基因的差异。【结果】两组小鼠的终末体重没有明显差异。各样本DNA的测序有效率足够,肠道菌群的多样性存在一定差异。属放线菌门(Actinobacteria)的双歧杆菌(Bifidobacteriales)-B.pseudolongum分支和Coriobacteriia-Collinsella/Enterorhabdus分支的丰度在强化玉米饮食组的小鼠中显著升高,相应的宏基因组中涉及糖酵解和胆汁酸合成的一些酶和功能单元的含量也在强化玉米饮食组显著升高。【结论】强化玉米饮食可以提高肠道菌群中双歧杆菌等益生菌的丰度,增加宏基因组糖脂代谢相关基因和通路的含量,从而可能促进宿主的糖代谢功能。     

Integrated gut/liver microphysiological systems elucidates inflammatory inter‐tissue crosstalk

A capability for analyzing complex cellular communication among tissues is important in drug discovery and development, and in vitro technologies for doing so are required for human applications. A prominent instance is communication between the gut and the liver, whereby perturbations of one tissue can influence behavior of the other. Here, we present a study on human gut‐liver tissue interactions under normal and inflammatory contexts, via an integrative multi‐organ platform comprising human liver (hepatocytes and Kupffer cells), and intestinal (enterocytes, goblet cells, and dendritic cells) models. Our results demonstrated long‐term (>2 weeks) maintenance of intestinal (e.g., barrier integrity) and hepatic (e.g., albumin) functions in baseline interaction. Gene expression data comparing liver in interaction with gut, versus isolation, revealed modulation of bile acid metabolism. Intestinal FGF19 secretion and associated inhibition of hepatic CYP7A1 expression provided evidence of physiologically relevant gut‐liver crosstalk. Moreover, significant non‐linear modulation of cytokine responses was observed under inflammatory gut‐liver interaction; for example, production of CXCR3 ligands (CXCL9,10,11) was synergistically enhanced. RNA‐seq analysis revealed significant upregulation of IFNα/β/γ signaling during inflammatory gut‐liver crosstalk, with these pathways implicated in the synergistic CXCR3 chemokine production. Exacerbated inflammatory response in gut‐liver interaction also negatively affected tissue‐specific functions (e.g., liver metabolism). These findings illustrate how an integrated multi‐tissue platform can generate insights useful for understanding complex pathophysiological processes such as inflammatory organ crosstalk. Biotechnol. Bioeng. 2017;114: 2648–2659. © 2017 Wiley Periodicals, Inc.     

Colony contact contributes to the diversity of gut bacteria in bumblebees (Bombus terrestris)

Social bees, like honeybees and bumblebees, have a close contact with nest mates of different developmental stages and generations. This could enhance bacterial transfer between nest mates and offers opportunities for direct transfer of symbionts from one generation to the next, resulting in a stable host specific gut microbiota. Gut symbionts of honeybees and bumblebees have been suggested to contribute in digestion and protection against parasites and pathogens. Here we studied the impact of contact with the bumblebee colony on the colonization potential of the bacterial families (i.e., Neisseriaceae, Orbaceae, Lactobacillaceae and Bifidobacteriaceae) occurring in the gut of adult bumblebees (Bombus terrestris). Bacterial profiles of the gut microbiota of B. terrestris were determined based on the hypervariable V4 region of the 16S rRNA using paired‐end Illumina sequencing. In our experiments, we created different groups in which we gradually reduced the contact with nest mates and hive material. We made 3 observations: (i) reducing the contact between the colony and the bumblebee during adult life resulted in a significant drop in the relative abundance of Lactobacillus bombicola and Lactobacillus bombi; (ii) Bifidobacteriaceae required contact with nest mates to colonize the gut of B. terrestris and a significant lower bacterial diversity was observed in bumblebees that were completely excluded from colony contact during the adult life; (iii) Snodgrassella and Gilliamella were able to colonize the gut of the adult bumblebee without any direct contact with nest mates in the adult life stage. These results indicate the impact of the colony life on the diversity of the characteristic bumblebee gut bacteria.     

Effect of β-1/3,1/6-glucan upon immune responses and bacteria in the gut of healthy common carp (Cyprinus carpio)

β-glucans are frequently included in the diet of healthy common carp Cyprinus carpio as a pre-emptive measure for combatting disease. In order to study the effect this has on the relationship between the gut bacteria and host immune response, carp were maintained on either a β-glucan free diet or feed containing 0.1% MacroGard®, a β-1/3, 1/6-glucan, for up to 7 weeks and analysis of innate immune gene expression and molecular analysis of the gut bacteria was performed. The data reveals feeding of MacroGard® to healthy carp does not induce bactericidal innate immune gene expression in the gut but does appear to alter bacterial species richness that did not have a negative effect on overall health. Analysis of innate immune gene expression within the upper midgut revealed that there were significant changes over time in the expression of Interleukin (il)-1β, inducible nitric oxide synthase (inos), mucin (muc2) and C-reactive protein (crp2). Diet did not affect the number of copies of the bacterial 16s rDNA gene in the gut, used as a as a measure of total bacteria population size. However, PCR-denaturing gradient gel electrophoresis (DGGE) analysis revealed a shift in bacterial species richness with MacroGard feeding. Bactericidal immune gene expression of crp2, muc2 and il-1β was weakly correlated with gut bacteria population size indicating a potentially limited role of these genes in interacting with the gut bacteria in healthy carp in order to maintain gut homeostatic conditions. These findings highlight the importance of considering both host immunity and the microbiome together in order to fully elucidate the effeect of immunomodulants, such as β-glucans, upon gut health.