双相情感障碍患者健康状况与肠道菌群的相关性分析

探讨双相情感障碍（BD）患者健康状况与肠道菌群的相关性,为该类患者的治疗提供参考。

收集我院BD患者（BD组）和健康人群（健康对照组）的粪便样本,使用QIAamp^® DNA粪便抽提试剂盒进行粪便样本的总DNA提取,随后进行16S rRNA基因测序,使用主成分分析（PCoA）探究健康对照组和BD组患者肠道菌群多样性情况。采用BD患者自我报告健康问卷评估患者的健康状况。

BD患者肠道菌群Shannon指数（P = 0.020 5）、Chao指数（P = 0.025 1）和Simpson指数（P = 0.020 8）显著低于健康对照组（均P＜0.05）。加权的Unifrac PCoA分析表明,BD组患者肠道菌群相似性低于健康对照组。两组对象肠道菌群门水平上有差异的菌群为放线菌门和厚壁菌门;属、种水平上的差异菌群有普氏粪杆菌、梭状芽胞杆菌和瘤胃球菌属。两组对象在功能性身体健康（PCS）、心理健康（MCS）、睡眠质量（PSQI）、抑郁（PHQ-9）、焦虑（GAD-7）和狂躁（ASRM）的平均总成绩上差异均有统计学意义（均P＜0.05）。BD患者的功能性身体健康得分与肠道放线菌门、厚壁菌门、拟杆菌属、梭状芽胞杆菌呈负相关,与普氏粪杆菌以及瘤胃球菌属呈正相关。

健康对照组和BD组患者的肠道菌群结构大致相似,BD患者的肠道菌群多样性低于健康对照组,BD患者健康状况与肠道菌群存在一定的相关性。

     

急性胃肠功能损伤患者肠道菌群及其代谢产物的分析

分析重症患者合并急性胃肠功能损伤（AGI）的肠道菌群变化的特征。

采用观察性研究方法,选择2021年1月至2022年12月本院重症监护病房收治的患者36例,根据是否发生AGI分为AGI组（n = 18）和non-AGI组（n = 18）,记录入科时患者急性生理与慢性健康状况评分Ⅱ和序贯器官衰竭评估评分,测定患者入科时超敏C反应蛋白、降钙素原以及第1次粪便样本的乙酸、丙酸、丁酸的水平,通过16S rDNA测序分析粪便样本的菌群多样性,比较两组患者肠道菌群差异。

AGI组患者肠道乙酸、丙酸、丁酸水平较non-AGI组显著降低,差异均有统计学意义（均P＜0.05）。AGI组患者肠道菌群alpha多样性显著低于non-AGI组。在细菌门分类水平上,两组患者肠道菌群差异无统计学意义;属水平比较,AGI组患者肠道菌群中肠球菌属、埃希—志贺菌属的相对丰度显著高于non-AGI组（均P＜0.05）,non-AGI组中双歧杆菌属相对丰度显著升高（P＜0.05）。

合并AGI重症患者肠道代谢功能失衡,菌群结构发生改变,为益生菌辅助治疗重症患者提供一定临床研究依据。

     

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。

     

红茶对新生幼鼠肠道菌群形成的影响

探讨红茶对新生幼鼠肠道菌群形成的影响,为从微生态角度研究红茶在人体肠道菌群形成过程中的作用机制奠定基础。

利用宏基因组测序技术检测4周龄新生幼鼠（4weeks组,n = 30）、12周龄正常对照组小鼠（control组,n = 15）和12周龄喂饲红茶水实验组小鼠（teadrink组,n = 15）的肠道菌群分布,分析3组样本的菌群差异情况,探求红茶对新生幼鼠肠道菌群形成的影响。

与control组相比,teadrink组小鼠肠道拟杆菌门（t = −7.711,P＜0.001）、拟杆菌科（t = −3.411,P = 0.009）、长尾嗤菌体科（t = −2.515,P = 0.036）、拟杆菌属（t = −2.693,P = 0.027）、邓肯菌属（t = −2.434,P = 0.041）、居海事城球杆菌属（t = −3.327,P = 0.029）、迪博邓肯菌（t = −2.679,P = 0.028）、普通居海事城球杆菌（t = −3.401,P = 0.027）和Duncaniella_sp._C9（t = −3.104,P = 0.035）相对丰度显著增加,厚壁菌门（t = 8.952,P＜0.001）、乳杆菌科（t = 13.102,P＜0.001）、消化链球菌科（t = 3.665,P = 0.021）、爱格菌科（t = 4.481,P = 0.002）、理研菌科（t = 3.626,P = 0.022）、乳杆菌属（t = 5.542,P = 0.004）、黏液乳杆菌属（t = 6.334,P = 0.002）、龙包茨菌属（t = 3.785,P = 0.005）、阿德勒菌属（t = 4.504,P = 0.002）、约氏乳杆菌（t = 4.282,P = 0.011）和罗伊氏粘液乳杆菌（t = 6.156,P = 0.003）相对丰度显著减少。与4weeks组相比,teadrink组小鼠肠道菌群分布差异大于control组。

红茶对新生幼鼠肠道菌群的形成能够产生影响,不同丰度的菌群可能通过调节碳水化合物代谢等途径来达到改善肠道菌群结构、增强肠道稳态的目的,具体代谢机制有待深入研究。

     

内毒素血症对新生鼠肠道菌群的影响

利用高通量测序技术分析内毒素血症新生鼠肠道菌群的变化, 探究肠道菌群与内毒素血症的关系, 为临床诊治提供思路。

复制新生大鼠内毒素损伤模型, 注射LPS后第24小时、第3天、第7天分别处死新生大鼠, 留取粪便并将对照组(C1组6只、C3组5只、C7组7只)和LPS组(L1组5只、L3组5只、L7组5只)按处死天数各分为3组。高通量测序分析各组间菌群多样性及相对丰度差异。

(1) Alpha多样性分析提示对照组和LPS组菌群多样性及丰度有显著差异, C3组较L3组Shannon指数均值小(t=-3.386 8, P=0.009 5), Simpson指数均值大(t=3.102 4, P=0.014 6);C7组较L7组Shannon指数均值大(t=2.459 4, P=0.033 7), Simpson指数均值小(t=-2.475 6, P=0.032 8)。(2)物种组成分析表明LPS组的菌群结构发生改变, 在门水平LPS组较对照组变形菌门相对丰度高, 厚壁菌门相对丰度低; 在属水平上LPS组较对照组埃希菌-志贺菌属相对丰度高, 乳杆菌属相对丰度低; 且随着天数的递增LPS组埃希菌-志贺菌属呈递增趋势, 红球菌属呈递减趋势。

内毒素血症可以改变新生鼠肠道菌群的组成, 并与肠道菌群失调有一定的关系。

     

基于16S rDNA技术研究隔药饼灸对高脂血症兔肠道菌群属水平的影响

研究隔药饼灸对高脂血症兔属水平肠道菌群的作用,筛选相关菌属。

将24只兔按随机数表法分为正常组、模型组和隔药饼灸组,每组8只;干预12周后,观察TC、TG、LDL-C水平的变化,采用16S rDNA高通量测序技术分析属水平菌落差异。

与模型组比较,隔药饼灸组兔血清LDL-C、TG、TC水平均下降（均P＜0.05）。隔药饼灸组肠道菌群结构发生改善,un_f_Muribaculaceae、un_o_Gastranaerophilales、瘤胃球菌科UCG-014属、阿克曼菌属相对丰度均显著提高（均P＜0.05）,毛螺菌属NK4A136、瘤胃梭菌属6、拟杆菌属相对丰度均降低（均P＜0.05）。

隔药饼灸能改善异常血脂及调整菌群结构,可能与上调un_f_Muribaculaceae、un_o_Gastranaerophilales、瘤胃球菌科UCG-014属、阿克曼菌属相对丰度,降低毛螺菌属NK4A136、瘤胃梭菌属6、拟杆菌属相对丰度有关。

     

裕固族血脂异常人群肠道菌群结构特征分析

探究生活在相同环境下的同一民族血脂异常人群与健康人群的肠道菌群差异,为血脂异常的精准预防和治疗提供参考。

收集甘肃肃南县裕固族血脂异常人群和健康人群粪便样本,提取细菌总DNA,通过16S rDNA高通量测序和生物信息学技术,分析2组人群肠道菌群的差异。

裕固族健康组人群肠道菌群分属26个门,73个纲,169个目,301个科,709个属,门水平上丰度＞1%的物种有4个,属水平上丰度＞1%的物种有22个。裕固族血脂异常组人群肠道菌群分属29个门,75个纲,280个目,304个科,702个属,门水平上丰度＞1%的物种有4个,属水平上丰度＞1%的物种有15个。裕固族血脂异常组人群肠道菌群与健康组间拟杆菌门、厚壁菌门、放线菌门水平以及F/B比值存在显著差异,Р＜0.05的差异物种有5个,Subdoligranulum、Christensenellaceae_R-7_group及Dialister与血脂水平呈负相关,Lachnoclostridium、Parasutterella与血脂水平呈正相关。

肃南县裕固族血脂异常组人群肠道菌群结构与健康组存在差异,为下一步关联分析肠道菌群与血脂异常及环境因素提供了基础数据。

     

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。

     

基于16S rRNA高通量测序技术分析福州地区慢传输型便秘患者肠道菌群的变化

运用16S rRNA高通量测序技术分析福州地区慢传输型便秘(STC)患者肠道菌群变化的特征。

纳入60例STC患者和健康志愿者20例, 留取新鲜粪便样本, 冰块运送至实验室并存放于-80度冰箱, 应用16S rRNA高通量测序技术, 分析各组肠道菌群的生物多样性与结构组成。

测序后共得到1 702 004 524条有效序列, 样本序列平均有效长度为414.1 bp, 总样本平均序列条数为2 127 505.7条。与对照组比较, STC患者肠道菌群丰度指数Ace指数、Chao指数和肠道菌群多样性指数Shannon指数下降(P < 0.05), 肠道菌群多样性指数Simpson指数显著升高(P < 0.05)。在门水平上, STC组以拟杆菌门、放线菌门为主, 正常对照组以厚壁菌门为主。在属水平上, STC组以拟杆菌属(Bacteroides)、肠杆菌科(Enterobacteriaceae)、丹毒杆菌属(Erysipelatoclostridium)、巨单胞菌属(Megamonas)为主, 正常对照组以乳酸杆菌属(Lactobacillus)、双歧杆菌属(Bifidobacterium)、布劳特菌属(Blautia)为主。

STC患者肠道菌群发生紊乱, 表现为丰度及多样性下降, 菌群结构发生改变, 可能与慢传输型便秘的发生发展有关。

     

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。

     

Diet strongly influences the gut microbiota of surgeonfishes

Intestinal tracts are among the most densely populated microbial ecosystems. Gut microbiota and their influence on the host have been well characterized in terrestrial vertebrates but much less so in fish. This is especially true for coral reef fishes, which are among the most abundant groups of vertebrates on earth. Surgeonfishes (family: Acanthuridae) are part of a large and diverse family of reef fish that display a wide range of feeding behaviours, which in turn has a strong impact on the reef ecology. Here, we studied the composition of the gut microbiota of nine surgeonfish and three nonsurgeonfish species from the Red Sea. High‐throughput pyrosequencing results showed that members of the phylum Firmicutes, especially of the genus Epulopiscium, were dominant in the gut microbiota of seven surgeonfishes. Even so, there were large inter‐ and intraspecies differences in the diversity of surgeonfish microbiota. Replicates of the same host species shared only a small number of operational taxonomic units (OTUs), although these accounted for most of the sequences. There was a statistically significant correlation between the phylogeny of the host and their gut microbiota, but the two were not completely congruent. Notably, the gut microbiota of three nonsurgeonfish species clustered with some surgeonfish species. The microbiota of the macro‐ and microalgavores was distinct, while the microbiota of the others (carnivores, omnivores and detritivores) seemed to be transient and dynamic. Despite some anomalies, both host phylogeny and diet were important drivers for the intestinal microbial community structure of surgeonfishes from the Red Sea.     

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.

     

The inconstant gut microbiota of Drosophila species revealed by 16S rRNA gene analysis

The gut microorganisms in some animals are reported to include a core microbiota of consistently associated bacteria that is ecologically distinctive and may have coevolved with the host. The core microbiota is promoted by positive interactions among bacteria, favoring shared persistence; its retention over evolutionary timescales is evident as congruence between host phylogeny and bacterial community composition. This study applied multiple analyses to investigate variation in the composition of gut microbiota in drosophilid flies. First, the prevalence of five previously described gut bacteria (Acetobacter and Lactobacillus species) in individual flies of 21 strains (10 Drosophila species) were determined. Most bacteria were not present in all individuals of most strains, and bacterial species pairs co-occurred in individual flies less frequently than predicted by chance, contrary to expectations of a core microbiota. A complementary pyrosequencing analysis of 16S rRNA gene amplicons from the gut microbiota of 11 Drosophila species identified 209 bacterial operational taxonomic units (OTUs), with near-saturating sampling of sequences, but none of the OTUs was common to all host species. Furthermore, in both of two independent sets of Drosophila species, the gut bacterial community composition was not congruent with host phylogeny. The final analysis identified no common OTUs across three wild and four laboratory samples of D. melanogaster. Our results yielded no consistent evidence for a core microbiota in Drosophila. We conclude that the taxonomic composition of gut microbiota varies widely within and among Drosophila populations and species. This is reminiscent of the patterns of bacterial composition in guts of some other animals, including humans.     

Interactions between multiple helminths and the gut microbiota in wild rodents

The gut microbiota is vital to host health and, as such, it is important to elucidate the mechanisms altering its composition and diversity. Intestinal helminths are host immunomodulators and have evolved both temporally and spatially in close association with the gut microbiota, resulting in potential mechanistic interplay. Host–helminth and host–microbiota interactions are comparatively well-examined, unlike microbiota–helminth relationships, which typically focus on experimental infection with a single helminth species in laboratory animals. Here, in addition to a review of the literature on helminth–microbiota interactions, we examined empirically the association between microbiota diversity and composition and natural infection of multiple helminth species in wild mice (Apodemus flavicollis), using 16S rRNA gene catalogues (metataxonomics). In general, helminth presence is linked with high microbiota diversity, which may confer health benefits to the host. Within our wild rodent system variation in the composition and abundance of gut microbial taxa associated with helminths was specific to each helminth species and occurred both up- and downstream of a given helminth''s niche (gut position). The most pronounced helminth–microbiota association was between the presence of tapeworms in the small intestine and increased S24–7 (Bacteroidetes) family in the stomach. Helminths clearly have the potential to alter gut homeostasis. Free-living rodents with a diverse helminth community offer a useful model system that enables both correlative (this study) and manipulative inference to elucidate helminth–microbiota interactions.     

不同养殖场林麝肠道微生物组成和功能的差异

肠道疾病是养殖林麝(Moschus berezovskii)常见疾病。动物肠道微生物伴随宿主进化并与胃肠道构成了复杂的微生态系统。为探究不同饲养环境对圈养林麝肠道微生物组成和功能的影响,本研究对采自国内5个不同养殖场的215份粪便样品进行了16S rRNA基因高通量测序,对比分析不同养殖场林麝肠道微生物组成、多样性和功能的差异。结果显示,厚壁菌门和拟杆菌门是未喂食复合益生菌的祁连县养殖场林麝肠道菌群的绝对优势菌门,而喂食复合益生菌的甘肃两当县和陕西凤县的4家养殖场林麝肠道菌群的绝对优势菌门为厚壁菌门和变形菌门。不同养殖场林麝肠道菌群组成、优势菌门、优势菌属、潜在致病菌、代谢及疾病相关功能均有显著差异。祁连县养殖场林麝肠道微生物的α多样性和疾病相关功能表达量显著低于其他养殖场,并以肠型2为主,其主导菌为厚壁菌门、UCG-005和拟杆菌属;两当县和凤县的4家养殖场林麝肠道菌群潜在致病菌相对丰度较低。本研究推测食物组成差异可能是导致不同养殖场林麝肠道微生物差异的主要因素,复合益生菌的使用可能是导致α多样性和潜在致病菌下降的重要因素。该结果可为林麝的人工养殖和有效管理提供科学依据,也对人工饲养...     

基于16S rRNA基因扩增子测序分析日本囊对虾肠道菌群结构与功能的特征

【背景】肠道菌群在对虾的生理活动中起关键作用。日本囊对虾是我国海水养殖虾类中的主要品种之一,迄今为止有关其肠道菌群结构与功能的研究还鲜有报道。【目的】利用高通量测序技术探究日本囊对虾肠道菌群的组成结构与功能作用,揭示虾体肠道菌群与外源菌群结构间的相关性。【方法】60 d的养殖周期结束后,分别采集日本囊对虾肠道样品(归为虾肠组,n=3)、养殖水体样品(归为水体组,n=3)和对虾饲料样品(归为饲料组,n=3),提取各样品总DNA进行16SrRNA基因扩增子测序,基于生物信息学方法分析与比较样品间的菌群结构特征,并使用PICRUSt软件预测日本囊对虾肠道菌群功能。【结果】3组样品测序共获得822 713条有效序列,抽平处理后可聚类为3 416个OTU。虾肠组样品中有28.49%、59.30%的OTU可以依次在水体组、饲料组样品中检测到。门水平上,虾肠组样品中的优势菌门为变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)、厚壁菌门(Firmicutes)和梭杆菌门(Fusobacteria)。水体组、饲料组与虾肠组样品中的优势菌门结构不尽相同,但均由变形菌门和拟杆菌门组成。属水平上,虾肠组样品中的优势菌属包括弧菌属(Vibrio)、另类弧菌属(Aliivibrio)、假交替单胞菌属(Pseudoalteromonas)、假黄棕杆菌属(Pseudofulvibacter)、科尔韦尔氏菌属(Colwellia)、小纺锤状菌属(Fusibacter)、发光杆菌属(Photobacterium)、脱硫弧菌属(Desulfovibrio)、嗜冷杆菌属(Psychrobacter)以及弓形杆菌属(Arcobacter)。水体组和饲料组中检出的核心菌属结构与虾肠组相比有明显差异,其中海命菌属(Marivita)和假单胞菌属(Pseudomonas)分别为养殖水体及对虾饲料样品中的最优势菌属。PICRUSt预测结果显示,日本囊对虾肠道菌群的基因功能主要与新陈代谢类功能有关,包含氨基酸代谢、碳水化合物代谢与能量代谢等。【结论】日本囊对虾肠道菌群与其他种类对虾肠道菌群的结构间存在共性,其形成在一定程度上受到了外源菌群的干预,并在虾体的日常代谢活动中发挥了一定的作用。     

对虾等甲壳类动物肠道与血淋巴菌群的组成、功能与动态平衡调控

对虾等甲壳类动物体内存在2个菌群:肠道菌群和血淋巴菌群。肠道菌群的种类和数量较多,而血淋巴菌群较少。两种菌群均包含益生菌和致病菌,在宿主体内代谢、营养和免疫反应中发挥重要功能。肠道菌群动态平衡的调控主要通过双氧化酶产生的活性氧来完成;血淋巴菌群通过C-型凝集素调控的抗菌肽表达及酚氧化酶原激活系统来维持其动态平衡。阐明对虾等甲壳类体内菌群的组成、功能和动态平衡调控的机理,可以为对虾等经济甲壳类健康养殖的微生态制剂开发和疾病控制提供指导。     

Intestinal microbiota composition in fishes is influenced by host ecology and environment

The digestive tracts of vertebrates are colonized by complex assemblages of micro-organisms, collectively called the gut microbiota. Recent studies have revealed important contributions of gut microbiota to vertebrate health and disease, stimulating intense interest in understanding how gut microbial communities are assembled and how they impact host fitness (Sekirov et al. 2010). Although all vertebrates harbour a gut microbiota, current information on microbiota composition and function has been derived primarily from mammals. Comparisons of different mammalian species have revealed intriguing associations between gut microbiota composition and host diet, anatomy and phylogeny (Ley et al. 2008b). However, mammals constitute <10% of all vertebrate species, and it remains unclear whether similar associations exist in more diverse and ancient vertebrate lineages such as fish. In this issue, Sullam et al. (2012) make an important contribution toward identifying factors determining gut microbiota composition in fishes. The authors conducted a detailed meta-analysis of 25 bacterial 16S rRNA gene sequence libraries derived from the intestines of different fish species. To provide a broader context for their analysis, they compared these data sets to a large collection of 16S rRNA gene sequence data sets from diverse free-living and host-associated bacterial communities. Their results suggest that variation in gut microbiota composition in fishes is strongly correlated with species habitat salinity, trophic level and possibly taxonomy. Comparison of data sets from fish intestines and other environments revealed that fish gut microbiota compositions are often similar to those of other animals and contain relatively few free-living environmental bacteria. These results suggest that the gut microbiota composition of fishes is not a simple reflection of the micro-organisms in their local habitat but may result from host-specific selective pressures within the gut (Bevins & Salzman 2011).     

Diet drives convergent evolution of gut microbiomes in bamboo-eating species

Gut microbiota plays a critical role in host physiology and health. The coevolution between the host and its gut microbes facilitates animal adaptation to its specific ecological niche. Multiple factors such as host diet and phylogeny modulate the structure and function of gut microbiota. However, the relative contribution of each factor in shaping the structure of gut microbiota remains unclear. The giant(Ailuropoda melanoleuca) and red(Ailurus styani) pandas belong to different families of order Carnivora. They have evolved as obligate bamboo-feeders and can be used as a model system for studying the gut microbiome convergent evolution. Here, we compare the structure and function of gut microbiota of the two pandas with their carnivorous relatives using 16S rRNA and metagenome sequencing. We found that both panda species share more similarities in their gut microbiota structure with each other than each species shares with its carnivorous relatives. This indicates that the specialized herbivorous diet rather than host phylogeny is the dominant driver of gut microbiome convergence within Arctoidea.Metagenomic analysis revealed that the symbiotic gut microbiota of both pandas possesses a high level of starch and sucrose metabolism and vitamin B12 biosynthesis. These findings suggest a diet-driven convergence of gut microbiomes and provide new insight into host-microbiota coevolution of these endangered species.     

Metagenomic analysis reveals a functional signature for biomass degradation by cecal microbiota in the leaf-eating flying squirrel (Petaurista alborufus lena)

ABSTRACT: BACKGROUND: Animals co-evolve with their gut microbiota; the latter can perform complex metabolic reactions that cannot be done independently by the host. Although the importance of gut microbiota has been well demonstrated, there is a paucity of research regarding its role in foliage-foraging mammals with a specialized digestive system. RESULTS: In this study, a 16S rRNA gene survey and metagenomic sequencing were used to characterize genetic diversity and functional capability of cecal microbiota of the folivorous flying squirrel (Petaurista alborufus lena). Phylogenetic compositions of the cecal microbiota derived from 3 flying squirrels were dominated by Firmicutes. Based on end-sequences of fosmid clones from 1 flying squirrel, we inferred that microbial metabolism greatly contributed to intestinal functions, including degradation of carbohydrates, metabolism of proteins, and synthesis of vitamins. Moreover, 33 polysaccharide-degrading enzymes and 2 large genomic fragments containing a series of carbohydrate-associated genes were identified. CONCLUSIONS: Cecal microbiota of the leaf-eating flying squirrel have great metabolic potential for converting diverse plant materials into absorbable nutrients. The present study should serve as the basis for future investigations, using metagenomic approaches to elucidate the intricate mechanisms and interactions between host and gut microbiota of the flying squirrel digestive system, as well as other mammals with similar adaptations.