不同健康状况百岁老人肠道菌群的差异性

探索广西不同健康状况百岁老人肠道菌群的特征。

采用1∶1病例对照研究方法,在广西长寿地区按年龄收集不同健康状况的21对百岁老人粪便和血样标本,同时收集个体一般信息和食物摄入信息;使用标准量表测量身体机能和认知功能（MMSE）,测定血生化指标,采用16S rRNA的V4–V5区序列进行高通量测序分析肠道菌群的差异。

非健康组百岁老人较健康组百岁老人肠道菌群丰度和多样性显著降低（t = 3.987、4.000、3.703,均P＜0.001）;健康组百岁老人肠道菌群中蓝藻菌门（Cyanobacteria）、黏胶球形菌门（Lentisphaerae）丰度显著高于非健康组,拟杆菌门（Bacteroidetes）丰度显著低于非健康组;健康组百岁老人肠道菌群中别样杆菌属（Alistipes）、瘤胃球菌属（Ruminococcus）、气味细菌属（Odoribacter）、厌氧菌属（Anaerotruncus）、丁酸单胞菌属（Butyricimonas）丰度显著高于非健康组;非健康组百岁老人肠道菌群中拟杆菌纲（Bacteroidia）、拟杆菌目（Bacteroidales）、拟杆菌种（Bacteroides coprophius）丰度显著高于健康组;非健康组百岁老人身体机能、MMSE评分显著降低（t = 2.775、2.058,P = 0.008、0.046）。

广西不同健康状况百岁老人肠道菌群丰度和多样性具有显著特征,健康状况良好的百岁老人可能具有更好的肠道菌群构成。

     

摔跤运动员赛前集训控体重对肠道菌群及其代谢物的影响

探究赛前集训控体重对高水平摔跤运动员肠道菌群及代谢物的影响。

招募某省摔跤队运动员11名,在赛前集训期前后测量身体成分、收集粪便样本,采用16S rRNA基因测序技术检测肠道微生物的分布和丰度,利用非靶向代谢组学分析微生物的差异代谢产物及其所富集的功能。

摔跤运动员赛前集训后体重显著降低（P＜0.05）,但肌肉含量无显著差异。微生物组结果显示,控体重前后男女运动员肠道菌群alpha多样性和beta多样性均无显著差异。男性运动员Intestinibacter丰度显著增高（P＜0.05）,且与体重、四肢骨骼肌指数变化量呈正相关。代谢组学分析结果显示,男性运动员菌群差异代谢物富集于硫代谢和主要胆汁酸代谢相关通路,女性运动员菌群差异代谢物富集于神经活性配体—受体交互相关信号通路;Intestinibacter丰度变化与胆汁酸7alpha-hydroxy-3-oxo-4-cholestenoate变化呈正相关。

赛前集训控体重未影响摔跤运动员肠道菌群生物多样性和整体物种构成,但可以改变男性摔跤运动员肠道菌群中产丁酸盐菌属的相对丰度,整体表现为运动员肠道菌群对控体重过程较为适应。

     

呼吸窘迫综合征新生儿肠道菌群的改变

探究呼吸窘迫综合征新生儿肠道菌群的改变,为该类患儿的治疗提供参考。

选取我院2020年4月至2022年4月收治的83例呼吸窘迫综合征新生儿作为试验组,另选我院同期健康新生儿83例作为对照组,收集两组对象粪便标本。对比两组对象肠道菌群的变化情况。

与对照组相比,试验组患儿肠道菌群Chaol指数和Shannon指数显著降低,Ace指数显著升高,差异均有统计学意义（均P＜0.05）。两组对象肠道厚壁菌门、变形菌门、链球菌属相对丰度对比差异均有统计学意义（均P＜0.05）。

呼吸窘迫综合征新生儿肠道菌群改变较大。

     

口服益生菌对根治性放疗宫颈癌患者放疗相关性腹泻及肠道菌群的影响

评价口服益生菌预防根治性放疗宫颈癌患者放疗相关性腹泻（RE）的有效性,并探讨益生菌对根治性放疗宫颈癌患者肠道菌群的影响。

选取2020年1月—2022年12月于广西医科大学附属肿瘤医院妇瘤科行根治性放化疗宫颈癌患者46例,随机分为口服益生菌组（OP组）和非口服益生菌组（NOP组）,每组各23例。采集两组放疗前后粪便标本,通过16S rDNA测序检测肠道菌群,分析肠道菌群多样性和组间的菌群差异。

OP组RE发生率为8.7%,NOP组RE发生率高达47.8%,两组差异具有统计学意义（P=0.009）。口服益生菌能够增加放疗病人肠道菌群丰富度,但不能逆转肠道菌群α−多样性下降（P=0.012）。放疗前后肠道菌群β−多样性差异不显著（P＞0.05）。物种丰度分析显示放疗后肠道菌群在门、科、属、种水平的组成均发生改变;特别是腹泻患者与非腹泻患者比较：放疗前惰性乳杆菌相对丰度较高,但在放疗后惰性乳杆菌相对丰度较低。

宫颈癌患者根治性放疗期间口服益生菌可有效预防放疗相关性腹泻的发生。放疗影响肠道菌群的组成,特别是显著降低肠道厌氧菌的相对丰度。

     

首发抑郁症患者肠道菌群特征及其与健康人群肠道菌群结构的差异

比较首发抑郁症患者与健康人群肠道菌群的差异,探讨抑郁症患者肠道菌群和抑郁症状间的关系,为抑郁症的发病机制研究及治疗提供一定的理论依据。

选择2019年10月至2020年9月我院收治的首发抑郁症患者及健康人群为研究对象,分为抑郁组（n = 23）和健康组（n = 31）。对研究对象肠道菌群16S rRNA基因中V4−V5区域片段进行基因测序,使用汉密尔顿抑郁量表对两组对象抑郁症状进行评估。检测两组对象肠道菌群α多样性、β多样性和组间差异。

首发抑郁症患者与健康人群肠道菌群多样性差异无统计学意义（均P＞0.05）。两组对象肠道拟杆菌门和拟杆菌纲的相对丰度差异有统计学意义（均P＜0.05）。两组对象芽胞杆菌目等的相对丰度差异有统计学意义（P＜0.05）。在属水平和种水平上,两组对象分别有28个菌属和40个菌种的丰度差异有统计学意义（均P＜0.05）。LEfSe分析显示,拟杆菌科、艾克曼菌科等10种菌科是造成两组对象肠道菌群差异的主要细菌。

首发抑郁症患者与健康人群肠道菌群多样性未发现显著差异,但抑郁症患者肠道菌群结构与健康人群相比发生了改变,主要体现在拟杆菌属等细菌在抑郁症患者肠道中的相对丰度显著上升。

     

16S rDNA测序研究高脂饮食诱导的高脂血症大鼠肠道菌群变化

通过高脂饮食诱导大鼠高脂血症, 采用16S rDNA测序检测高脂血症大鼠肠道菌群变化情况。

SD大鼠20只(清洁级), 按体质量随机分为模型组和对照组, 对照组大鼠给予维持饲料, 模型组大鼠给予高脂饲料。1周后检测血清总胆固醇(TC)、三酰甘油(TG)、低密度脂蛋白胆固醇(LDL-C)和高密度脂蛋白胆固醇(HDL-C)水平。采集大鼠粪便, 采用16S rDNA测序法对大鼠肠道菌群进行分析, 考察高脂血症大鼠肠道菌群变化情况。

高脂血症大鼠肠道菌群生物多样性(Alpha多样性和Beta多样性)发生显著变化, 肠型与对照组差异明显, 在门、科、属等多个水平差异均具有统计学意义。其中, 厚壁菌门(Firmicutes)和念珠菌门(Candidatus saccharibacteria)数量显著下降, 拟杆菌门(Bacteroidetes)、疣微菌门(Verrucomicrobia)、变形菌门(Proteobacteria)和放线菌门(Actinobacteria)数量显著升高。

高脂饮食诱导的高脂血症可引起大鼠肠道菌群发生显著变化。

     

莆田黑猪肠道菌群的动态变化及其对平均日增重的影响

本研究旨在揭示莆田黑猪肠道菌群在不同生长阶段的动态变化情况并探究其对平均日增重的影响。

本研究采集了60头莆田黑猪60日龄和240日龄时的粪便样品, 利用16S rRNA基因测序分析了肠道菌群组成随时间的变化。随后, 通过关联分析鉴别了与平均日增重显著相关的微生物类群和功能途径。

16S rRNA基因测序结果表明, 莆田黑猪肠道菌群α-多样性随着日龄增大而显著升高。相反, β-多样性则显著降低。随日龄增加, 肠道菌群中厚壁菌门的相对丰度显著降低, 圣诞岛盐菌门的相对丰度显著升高(P < 0.01)。此外, 普雷沃菌NK3B31、螺旋菌属、罗氏菌属、乳酸杆菌属和普雷沃菌UCG-003在60日龄组肠道菌群中显著富集, 密螺旋体属2则在240日龄组肠道菌群中具有更高的丰度。关联分析结果显示, 8个OTUs和19条功能途径与平均日增重显著相关, 与平均日增重相关的细菌可能通过参与复杂性多糖降解、短链脂肪酸代谢、免疫功能调控和炎症反应等过程影响莆田黑猪的生长。

本研究发现莆田黑猪肠道菌群在不同生长阶段会发生明显改变, 肠道菌群的变化对平均日增重具有重要影响。

     

慢性胃炎患者肠道菌群分析

探索慢性胃炎（CG）患者肠道菌群变化特点。

采集我院青年CG患者（CG组）和健康人群（NC组）的粪便样品,对其细菌16S rDNA V3—V4区域进行扩增并进行高通量测序,然后运用多种生物信息学手段进行分析。

CG组与NC组对象肠道菌群在门和科水平上均有不同之处,其中CG组对象有较高丰度的Actinobacteriota和较低丰度的Ruminococcaceae。CG组对象肠道菌群多样性及均一度均显著低于NC组（均P＜0.05）,但两者具有相似的丰富度水平。多元方差分析和相似性百分比分析均发现CG组和NC组对象肠道菌群有较大差异。Bifidobacterium、Blautia、Collinsella、Ruminococcus_torques_group和Streptococcus与CG患者密切相关。

CG患者的肠道菌群存在较大变化,其中Bifidobacterium、Blautia等细菌与CG的发生相关。

     

人体肠道菌群对二甲基亚砜的体外降解作用——

通过二甲基亚砜（DMSO）与肠道菌群相互作用机制的研究,为DMSO的降解及其在药物研究中的应用提供肠道菌群方面的理论依据。

采用分批发酵、气相色谱、气质联用和高通量测序技术研究DMSO的降解量与肠道菌群结构间的关系。

发酵液中主要检测到甲硫醚、二甲基砜、二甲基二硫醚及甲基硫代磺酸甲酯等DMSO相关代谢产物;与其他他汀相比,生理浓度氟伐他汀组菌群的DMSO降解效果最佳,可能与Proteobacteria及Solobacterium和Escherichia-Shigella等菌群的相对丰度增加有关。不同肠道菌群产二甲基硫醚（DMS）水平差异明显,DMS分解可能与硫代谢途径相关,涉及的微生物主要是Desulfovibrio。

人体肠道菌群可降解DMSO,其降解效率可能与Escherichia-Shigella的相对丰度有关,降解产物对人体肠道菌群结构无影响。

     

夏季老年慢性阻塞性肺疾病患者口咽菌群分析

分析夏季老年慢性阻塞性肺疾病（COPD）患者与健康人群的口咽菌群构成,旨在确定老年COPD患者与健康人群上呼吸道菌群间的差异。

选择2018年6—8月沈阳市沈阳医学院附属第二医院COPD患者29例和健康体检者25例,采集口咽拭子进行细菌16S rRNA高通量测序。通过菌群多样性分析、物种组成和物种差异分析,比较老年COPD患者与健康人群口咽部微生物的异同。

老年COPD患者口咽中菌群丰富度显著高于健康人群,物种多样性低于健康人群。在门水平上,老年COPD患者口咽菌群中拟杆菌门相对丰度降低,放线菌门相对丰度显著增高;在属水平上,老年COPD患者口咽菌群中罗氏菌属、放线菌属和劳特罗普氏菌属丰度均显著高于健康人群,奈瑟菌属和普雷沃菌属相对丰度降低,差异均具有统计学意义（P＜0.05）。

老年COPD患者口咽部正常菌群组成发生变化,机会致病菌如罗氏菌属、劳特罗普氏菌属比例增加,提示夏季老年COPD患者口咽菌群失调。

     

Gut microbiota are associated with sex and age of host: Evidence from semi‐provisioned rhesus macaques in southwest Guangxi,China

Host characteristics, such as sex and age, are closely associated with the structure and function of gut microbiota; however, less is known about the effects of age and sex on the gut microbiota of nonhuman primates, and therefore, our knowledge of interindividual variability in host gut microbiota is limited. In this study, 153 fecal samples from rhesus macaques (Macaca mulatta) were analyzed using high‐throughput 16S rRNA sequencing in order to explore associations between age and sex of the host and their gut microbiota. The results indicated that female macaques had higher alpha diversity and a more unique gut microbiota than did males. The proportion of Proteobacteria, Tenericutes, Cyanobacteria, unclassified bacteria, and Verrucomicrobia was higher in females than that in males. We also found that adults of both sexes had a higher alpha diversity, a higher proportion of norank Ruminococcaceae, Oscillospira, norank Lachnospiraceae, norank Clostridiales, and Succinivibrio, and a lower proportion of Enterococcus than immatures. Functional analyses revealed that the richness of metabolic pathways was higher in females than males and in adults compared with immatures. These results could be attributed to differences in the nutritional requirements and hormone levels of macaques of different sex and age classes. We conclude that variation in the gut microbiota of different sex and age classes of rhesus macaques may be linked to age‐ and sex‐specific differences in nutrient requirements and hormone levels. These results highlight the importance of host age and sex on the structure and function of the gut microbiota and the need to consider physiological traits when conducting studies on the gut microbiota.     

Differences in the gut microbiota between Cercopithecinae and Colobinae in captivity

The gut microbiome of captive primates can provide a window into their health and disease status. The diversity and composition of gut microbiota are influenced by not only host phylogeny, but also host diet. Old World monkeys (Cercopithecidae) are divided into two subfamilies: Cercopithecinae and Colobinae. The diet and physiological digestive features differ between these two subfamilies. Accordingly, highthroughput sequencing was used to examine gut microbiota differences between these two subfamilies, using data from 29 Cercopithecinae individuals and 19 Colobinae individuals raised in captivity. Through a comparative analysis of operational taxonomic units (OTUs), significant differences in the diversity and composition of gut microbiota were observed between Cercopithecinae and Colobinae. In particular, the gut microbiota of captive Old World monkeys clustered strongly by the two subfamilies. The Colobinae microbial diversity was higher than that of Cercopithecinae. Additionally, Firmicutes, Lactobacillaceae, Veillonellaceae, and Prevotella abundance were higher in Cercopithecinae, while Bacteroidetes, Ruminococcaceae, Christensenellaceae, Bacteroidaceae, and Acidaminococcaceae abundance were higher in Colobinae. PICRUSt analysis revealed that the predicted metagenomes of metabolic pathways associated with proteins, carbohydrates, and amino acids were significantly higher in Colobinae. In the context of host phylogeny, these differences between Cercopithecinae and Colobinae could reflect adaptations associated with their respective diets. This well-organized dataset is a valuable resource for future related research on primates and gut microbiota. Moreover, this study may provide useful insight into animal management practices and primate conservation.

     

圈养食叶猴的肠道菌群特征

充分认识圈养食叶猴的肠道菌群组成特征, 为饲养管理方法的改进提供参考依据。

通过MiSeq高通量测序平台对3个物种的19个个体[黑叶猴(n=5)、川金丝猴(n=9)和西非黑白疣猴(n=5)]的肠道菌群16S rRNA V4-V5区进行测序和分析。

食叶猴肠道菌群以厚壁菌门和拟杆菌门为优势菌门, 瘤胃菌科、普氏菌科、理研菌科和毛螺菌科为优势菌科, 普氏菌属、密螺旋体属和瘤胃球菌属为优势菌属; 食叶猴物种间肠道菌群组成存在显著差异, 肠道菌群按照宿主物种聚类, 而不受环境因素的影响。

宿主物种是决定肠道微生物组成的重要因素, 食叶猴肠道菌群特征反映了宿主对其食性的适应。

     

糖脂代谢性疾病模型小鼠肠道菌群特征分析

基于16S rDNA测序研究非酒精性脂肪性肝病(NAFLD)、2型糖尿病(T2D)及动脉粥样硬化(AS)小鼠的肠道菌群特征, 分析上述疾病肠道微生物的异同。

以SPF级C57BL/6J雄鼠为对象, 分别采用高脂饮食制备NAFLD模型, 高脂饮食联合小剂量链脲佐菌素腹腔注射建立T2D模型, ApoE^-/-小鼠高脂饮食诱导AS模型, 另设对照组, 每组10只。采用试剂盒测定小鼠血清中总胆固醇(TC)、三酰甘油(TG)、低密度脂蛋白胆固醇(LDL-C)的水平。收集粪便样本, 以Illumina MiSeq测序平台, 采用QIIME2软件对肠道菌群的可分类操作单元(OTUs)数量, Alpha、Beta多样性和菌群多样性指数以及差异菌门、菌属等进行综合分析与评价, 并对肠道菌群代谢功能进行预测。

与对照组小鼠比, T2D组、NAFLD组、AS组血清中TC、TG和LDL-C水平均显著升高, 菌群多样性指数显著降低(F=14.33, P < 0.01), Firmicutes/Bacteroidetes比值逐渐升高; 双歧杆菌属(Bifidobacterium)丰度在AS组、T2D组中显著增加(F=12.15, P < 0.01), 在NAFLD组中显著下降(F=12.15, P < 0.05), 乳杆菌属(Lactobacillus)丰度在NAFLD组、AS组中著降低(F=9.35, P < 0.01), 在T2D组中显著降低。关联分析表明Lactobacillus、Akkermansia等与血脂呈负相关, Faecalibaculum、Blautia等与血脂呈正相关。肠道菌群参与代谢性疾病主要涉及碳水化合物代谢、氨基酸代谢、脂质代谢以及能量代谢等通路。

本研究阐明了NAFLD、T2D、AS肠道微生物组成与变化的共性和个性特征, 为靶向调控肠道微生物治疗代谢性疾病提供科学依据。

     

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。     

Housing condition-associated changes in gut microbiota further affect the host response to diet-induced nonalcoholic fatty liver

Diet-induced obesity is the most widely used animal model for studying nonalcoholic fatty liver disease (NAFLD). However, the physiological effects of a high-fat diet (HFD) are inconsistent between different studies. To elucidate this mystery, mice raised with conventional (CONV), specific pathogen-free (SPF) and gentamicin (G) treatments and fed with standard diet (STD) or HFD were analyzed in terms of their physiology, gut microbiota composition, hepatic steatosis and inflammation. Serum biochemistry showed increased levels of cholesterol and aspartate aminotransferase in the G-STD and CONV-HFD groups, respectively. The CONV-HFD group exhibited more inflammatory foci compared to the SPF-HFD and G-HFD groups. Furthermore, immunohistochemistry staining revealed the infiltration of Kupffer cells in the liver, consistent with increased mRNA levels of MCP-1, CD36 and TLR4. Principal coordinate analysis and the cladogram of LEfSe showed that the distinguished clusters of gut microbiota were dependent on housing conditions. The Rikenellaceae, F16 and Desulfovibrionaceae were strongly correlated with hepatic inflammation. Otherwise, higher NAFLD activity score correlated with altered relative abundances of Bacteroidetes and Firmicutes. In conclusion, gut microbiota varying with housing condition may be pivotal for the host response to HFD.     

Gut microbiota in wild and captive Guizhou snub‐nosed monkeys,Rhinopithecus brelichi

Many colobine species—including the endangered Guizhou snub‐nosed monkey (Rhinopithecus brelichi) are difficult to maintain in captivity and frequently exhibit gastrointestinal (GI) problems. GI problems are commonly linked to alterations in the gut microbiota, which lead us to examine the gut microbial communities of wild and captive R. brelichi. We used high‐throughput sequencing of the 16S rRNA gene to compare the gut microbiota of wild (N = 7) and captive (N = 8) R. brelichi. Wild monkeys exhibited increased gut microbial diversity based on the Chao1 but not Shannon diversity metric and greater relative abundances of bacteria in the Lachnospiraceae and Ruminococcaceae families. Microbes in these families digest complex plant materials and produce butyrate, a short chain fatty acid critical to colonocyte health. Captive monkeys had greater relative abundances of Prevotella and Bacteroides species, which degrade simple sugars and carbohydrates, like those present in fruits and cornmeal, two staples of the captive R. brelichi diet. Captive monkeys also had a greater abundance of Akkermansia species, a microbe that can thrive in the face of host malnutrition. Taken together, these findings suggest that poor health in captive R. brelichi may be linked to diet and an altered gut microbiota.     

The gut microbiota profile in psoriasis: a Brazilian case-control study

The pathogenesis of psoriasis, an immune-mediated chronic inflammatory skin disease, remains unclear. Studies have shown an association between psoriasis and intestinal inflammation; in this context, the influence of the gut microbiota on the immune response of psoriasis has become a focus of recent research. The present research evaluated the composition and diversity of the gut microbiota of 21 participants with psoriasis from a Brazilian referral dermatology service compared to 24 healthy controls. A stool sample was collected from each participant at the time of inclusion in the study, and the samples were analysed by sequencing the 16S rRNA gene. The recruitment of research participants involved matching between groups by sex, age, body mass index, comorbidities and smoking and the exclusion of several criteria that could potentially influence the gut microbiota and the interpretation of the data. There was an increase in the Dialister genus and Prevotella copri species in patients with psoriasis compared to the control group. A reduction in the Ruminococcus, Lachnospira and Blautia genera, as well as in the Akkermansia muciniphila species, was also verified in the psoriasis group compared to the control group. Furthermore, patients with psoriasis exhibited less gut microbiota diversity than controls.     

Genotype Is a Stronger Determinant than Sex of the Mouse Gut Microbiota

The mammalian gut microbiota is considered to be determined mostly by diet, while the effect of genotype is still controversial. Here, we examined the effect of genotype on the gut microbiota in normal populations, exhibiting only natural polymorphisms, and evaluated this effect in comparison to the effect of sex. DNA fingerprinting approaches were used to profile the gut microbiota of eight different recombinant inbred mouse lines of the collaborative cross consortium, whose level of genetic diversity mimics that of a natural human population. Analyses based on automated ribosomal internal transcribed spacer analysis demonstrated significant higher similarity of the gut microbiota composition within mouse lines than between them or within same-gender groups. Thus, genetic background significantly impacts the microbiota composition and is a stronger determinant than gender. These findings imply that genetic polymorphisms help shape the intestinal microbiota of mammals and consequently could affect host susceptibility to diseases.     

Murine gut microbiota is defined by host genetics and modulates variation of metabolic traits

The gastrointestinal tract harbors a complex and diverse microbiota that has an important role in host metabolism. Microbial diversity is influenced by a combination of environmental and host genetic factors and is associated with several polygenic diseases. In this study we combined next-generation sequencing, genetic mapping, and a set of physiological traits of the BXD mouse population to explore genetic factors that explain differences in gut microbiota and its impact on metabolic traits. Molecular profiling of the gut microbiota revealed important quantitative differences in microbial composition among BXD strains. These differences in gut microbial composition are influenced by host-genetics, which is complex and involves many loci. Linkage analysis defined Quantitative Trait Loci (QTLs) restricted to a particular taxon, branch or that influenced the variation of taxa across phyla. Gene expression within the gastrointestinal tract and sequence analysis of the parental genomes in the QTL regions uncovered candidate genes with potential to alter gut immunological profiles and impact the balance between gut microbial communities. A QTL region on Chr 4 that overlaps several interferon genes modulates the population of Bacteroides, and potentially Bacteroidetes and Firmicutes-the predominant BXD gut phyla. Irak4, a signaling molecule in the Toll-like receptor pathways is a candidate for the QTL on Chr15 that modulates Rikenellaceae, whereas Tgfb3, a cytokine modulating the barrier function of the intestine and tolerance to commensal bacteria, overlaps a QTL on Chr 12 that influence Prevotellaceae. Relationships between gut microflora, morphological and metabolic traits were uncovered, some potentially a result of common genetic sources of variation.