福建省3座水库库心沉积物聚磷菌的群落特征

聚磷菌在水库沉积物磷的代谢循环中起着重要作用.采用T-RFLP技术和克隆测序,以多聚磷酸盐激酶基因(ppk1)作为标记基因,研究对比了福建省3座富营养化水库(九龙江西陂水库、平潭三十六脚湖水库和三明东牙溪水库)库心沉积物中聚磷菌的多样性及群落结构.结果表明:3座水库库心沉积物聚磷菌的多样性存在一定差异,但不显著,以三十六脚湖库心样品中聚磷菌多样性最高(Shannon指数H=2.89±0.03,Simpson指数D=0.06±0.01).克隆测序和比对结果分析表明,三十六脚湖水库沉积物样品中聚磷菌种类最多,结构最复杂,这与T-RFLP的结果一致.3座水库库心沉积物样品中聚磷菌优势菌属差异较为明显,但均以变形菌门、放线菌门和酸杆菌门为主,这3个门在3座水库库心沉积物样品中所占比重分别达74.5%、85.0%和75.0%.其中,变形菌门中的厌氧粘细菌属、酸杆菌门中的Solibacter属在3座水库库心沉积物样品中均为优势菌属.沉积物中Fe/Al-P与聚磷菌多样性指数的相关性最显著.Fe/Al-P对聚磷菌群落结构影响最为显著,3个水库共有优势菌属厌氧粘细菌与各形态磷呈正相关,且与OP、Ca-P等难溶解性磷呈显著相关,Solibacter与各形态磷均呈负相关.表明聚磷菌与富营养化水库沉积物磷代谢循环密切相关.     

环境因素对东平湖沉积物细菌群落结构的影响

【目的】探讨环境因素对东平湖沉积物细菌群落结构的影响。【方法】应用T-RFLP(Terminal RestrictionFragment Length Polymorphism)技术分析和比较了6个不同位置的东平湖沉积物在丰水期和枯水期的细菌多样性,并结合不同样品环境因子的差异,采用主成分分析(PCA)和典型对应分析(CCA),探讨了环境因子对细菌多样性的影响。【结果】不同沉积物样品的T-RFLP图谱具有较高的相似性。除2号样品外,所有枯水期样品的细菌群落具有较高的丰富度、多样性、均匀度和较低的优势度。CCA结果表明,558bp T-RF的丰度与总磷、总氮、总有机碳、铵态氮和硝态氮含量呈负相关而与碳氮比和水深呈正相关;64.5、164、509和543bp T-RFs的丰度与总氮、总有机碳、铵态氮、硝态氮、碳氮比和水深呈正相关;而其它14种主要的T-RFs在不同样品间分布较为稳定受环境因子影响不大。90、136.5、138和488bp等T-RFs可能代表了东平湖沉积物中占优势地位的土著菌群。通过Phylogenetic Assignment Tool在线分析结果推测,东平湖沉积物中的优势菌群可能属于Firmicutes和Proteobacteria门。【结论】环境因素对东平湖沉积物的细菌多样性产生显著影响,但对其土著菌群的影响不大。     

退耕还湿后土壤细菌群落结构和生物量变化过程

土壤细菌对湿地生态系统功能和健康维持起着重要作用。以菜子湖原始湿地、不同退耕年限湿地(3a、7a、11a和21a)和仍耕作油菜地土壤为研究对象,应用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)、高通量测序和磷脂脂肪酸(PLFAs)方法分析土壤细菌群落组成和生物量,探讨它们在退耕还湿后的变化过程及其影响因素。结果表明,退耕还湿后土壤变形菌门(α-变形菌纲、β-变形菌纲和δ-变形菌纲)、酸杆菌门(酸杆菌纲和全噬菌纲)、Nitrospinae(Nitrospinia纲)和硝化螺旋菌门(硝化螺旋菌纲)相对丰度先增高后降低;这些参与氮循环的土壤细菌对退耕后湿地生态恢复过程中土壤氮素提升起着重要作用。与农业生产活动密切关联的厚壁菌门(芽孢杆菌纲和梭菌纲)和放线菌门(放线菌纲)相对丰度逐渐降低。湿地土壤细菌多样性在退耕初期(3—7a)上升达到最大,退耕中后期逐渐降低。表层土壤各类群细菌生物量逐渐升高,亚表层土壤各类群细菌生物量则先降后升再降。水分条件和容重是与研究区土壤细菌群落结构和多样性密切相关的土壤因子,而全氮是与土壤细菌生物量密切相关的土壤因子。研究从生态过程视角解析了土壤细菌群落较详...     

山西左云县采煤区人工湿地冬季沉积物细菌群落多样性

【背景】人工湿地处理煤炭矿井废水效果显著,而关于人工湿地沉积物的细菌群落结构和特征研究较少。【目的】阐明人工湿地净化采煤区废水的效应和细菌群落结构及特征。【方法】对山西省左云县采煤区人工湿地不同采样点水质进行监测,利用高通量测序技术对人工湿地沉积物中细菌16S rRNA基因V3-V4区进行测序,分析沉积物中细菌群落组成。【结果】采煤区废水流经人工湿地后水质得到有效改善,其中生化需氧量(Biochemical oxygen demand,BOD5)、化学需氧量(Chemical oxygen demand,CODCr)、总氮(Total nitrogen,TN)、总磷(Total phosphorus,TP)去除率分别达到76.2%、93.4%、73.4%和99.3%;测序共获得2 832个操作分类单元(Operational taxonomic units,OTUs),共753个属,分布于51个门的150个纲;4个采样点中优势菌门为变形菌门(Proteobacteria,50%-64.7%)和拟杆菌门(Bacteroidetes,15.8%-21.2%),变形菌门中优势菌纲为β-变形菌纲和γ-变形菌纲,其中M1、M2、M3中富含氨氮氧化细菌的β-变形菌纲和γ-变形菌纲丰度最高;M4沉积物细菌OTU最多,多样性最高;沉积物特有优势菌属Sulfurimonas、Sulfuricurvum的相对丰度与NH4+-N的含量显著负相关,Azoarcus菌属相对丰度与TN存在显著正相关,Novosphingobium菌属相对丰度与TP含量存在显著正相关。【结论】煤矿废水流经人工湿地可得到有效的净化,细菌多样性在人工湿地生态功能中起到了决定作用。     

象山港网箱养殖对近海沉积物细菌群落的影响

微生物在有机物质分解、能量转移等生物地化循环中起着重要作用,研究养殖活动对沉积物中微生物多样性的影响对正确评价近海生态系统结构和功能具有重要意义.结合沉积物的理化分析(T、pH、Eh和SO2-),通过T-RFLP(末端限制性片段长度多态性)分析了象山港网箱养殖对近海不同深度沉积物中细菌群落结构和多样性的影响,构建了对照区0-5 cm沉积物样品的细菌16S rRNA基因克隆文库,并进行了系统发育分析.结果表明,近海网箱养殖活动不但使象山港沉积物Eh、pH值等理化性质有所改变,而且使细菌的群落结构也发生了变化,变形细菌纲细菌的相对丰度降低,细菌群落的多样性和均匀度也显著降低,致使近海沉积物细菌群落由多样性高的稳定结构向多样性降低的不稳定结构转变.     

塔里木河中下游流域棉田及胡杨林土壤细菌群落结构及多样性研究

【背景】新疆绿洲生态系统的大规模农垦开发对当地生态环境产生了一系列影响,评估农业活动对新疆地区原始生态土壤细菌群落的影响对合理利用土地、开发农业资源具有指导意义。【目的】通过研究塔里木河中下游流域受农垦开发影响的棉田及未经历土地开垦的胡杨林土壤细菌群落结构及多样性的变化,探究农垦开发活动对土壤微生态的影响。【方法】利用国标法测定塔里木河中下游流域绿洲棉田及原始胡杨林全氮、总盐、有机质、碱解氮、有效磷、速效钾、pH等土壤理化性质;提取土壤总DNA,通过PCR扩增建立文库,用新一代Illumina HiSeq 2500测序技术对土样DNA进行16SrRNA基因(V4区)高通量测序;利用生物信息学分析细菌群落的α多样性(包括Chao1、Observed species、Phylogenetic diversity (PD)、Shannon、Simpson和Good’s coverage指数)、β多样性在两地的变化,基于线性判别分析流程[Lineardiscriminantanalysis(LDA)effectsizepipeline,LEfSe]分析在两地具有显著差异的细菌分类单元;结合土壤理化参数、群落功能预测分析可能影响两地细菌群落结构变化的主要因子。【结果】土壤基本理化性质分析:绿洲棉田与原始胡杨林相比,全氮、碱解氮、总盐、pH含量显著增加,土壤盐含量与全氮、碱解氮和pH呈显著正相关(P0.05);细菌多样性分析:α多样性指数Chao1、Observedspecies和PD在棉田样品中均显著低于胡杨林样品,Shannon指数差异虽不显著,但是也表现出同样的变化趋势;细菌群落组成分析:两组样品中的优势细菌依次为α-变形杆菌纲、放线菌门、芽单胞菌门、拟杆菌门、酸杆菌门、γ-变形菌纲、β-变形菌纲、δ-变形菌纲、绿弯菌门、厚壁菌门、浮霉菌门、泉古菌门和硝化螺旋菌门(丰度1%);差异分析的结果显示,新疆绿洲棉田土壤中显著富集的微生物主要包括酸杆菌门、放线菌门、绿弯菌门、厚壁菌门、黄杆菌纲、α-变形菌纲、γ-变形菌纲中的一些物种,以及泉古菌门中的Candidatus Nitrososphaera;新疆原始胡杨林土壤中显著富集的微生物主要包括绿菌门、δ-变形菌纲以及变形菌门中的其他物种,还包括泉古菌门中的Nitrosopumilus。主坐标分析(PCoA)结果显示,棉田生态系统的土壤细菌群落结构能够与胡杨林生态系统的群落结构明显分开,且前者的细菌群落结构一致性更高。功能预测结果显示,绿洲棉田的硝化作用显著高于原始胡杨林。冗余分析(RDA)结果表明全氮含量对细菌群落结构有显著影响。【结论】在长期耕种施肥等人为因素干扰下,绿洲棉田土壤细菌多样性和群落结构发生明显改变,细菌α多样性明显低于原始胡杨林,细菌β多样性差异减弱,同时一些与植物生长密切相关的细菌类群,如放线菌、硝化细菌等显著富集。该研究可为新疆绿洲棉田生态系统的开发利用现状提供数据参考。     

西藏热泉沉积物的硫氧化细菌多样性及其影响因素

【目的】探究西藏热泉沉积物中硫氧化细菌群落多样性及其环境影响因素。【方法】选取西藏5个地热区的25个热泉样点,现场测量各采样点的水体理化参数,并采集热泉水和沉积物样品。通过功能基因(硫代硫酸盐水解酶编码基因:soxB)克隆文库分析方法,研究沉积物样品中硫氧化细菌群落的组成和多样性,并统计分析其与环境参数之间的相关性。【结果】克隆文库分析结果显示,西藏热泉沉积物样品中的硫氧化细菌主要分属于α-Proteobacteria、β-Proteobacteria和γ-Proteobacteria纲。研究样品中的硫氧化菌群落香农指数与溶解有机碳的浓度(R=0.489,P0.05)呈显著正相关。另外,统计发现西藏各热泉之间的硫氧化菌群落组成差异较大,其优势硫氧化细菌种群差异明显,大多数样点的优势硫氧化细菌种群为β-Proteobacteria,少量样点以α-Proteobacteria和γ-Proteobacteria为主。Mantel检验结果显示,西藏热泉样品中的硫氧化细菌群落组成与温度、硫化物、电导率、海拔、总溶解固体和pH显著(P0.05)相关。【结论】西藏热泉沉积物中的硫氧化细菌群落广泛分布,且主要以变形菌门为主。地理隔离和理化差异导致了热泉沉积物样品间的硫氧化菌群落组成差异。     

水产养殖不同物种对水体和沉积物中细菌群落的影响

为探究水产养殖中养殖不同物种对水体和沉积物中细菌群落的影响,以养殖克氏原螯虾(Procambarus clarkii, PC)和中华鳖(Pelodiscus sinensis, PS)的水体和沉积物样品为研究对象,利用基于16S rRNA基因的高通量测序技术,对细菌群落多样性和群落组成进行分析,并结合环境因子,探究水产养殖对细菌群落的影响。结果显示,水体和沉积物中细菌群落的α多样性均呈现PS>PC的显著差异(P<0.05)。非度量多维尺度分析的结果显示,PC和PS区的水体和沉积物细菌群落结构均呈现明显差异。冗余分析(RDA)的结果表明,水体氨氮(NH~+₄-N)和硝酸盐氮(NO~-₃-N)是影响水体细菌群落结构的最主要环境因子,沉积物总氮(TN)、总磷(TP)和有机碳(OC)均对沉积物细菌群落结构有显著影响(P<0.05)。PC和PS区中的细菌隶属于34门、114纲、258目、504科和955属,水体中共筛选出了11个优势菌门(相对丰度>0.5%),沉积物中筛选出了13个。2个养殖区域的水体样品中共筛选出了15个优势(...     

Effects of fine root decomposition on bacterial community structure of four dominated tree species in Mount Taishan,China

为了理解细菌群落结构和多样性对森林生态系统细根凋落物分解的影响, 该研究以泰山4种主要优势造林树种刺槐(Robinia pseudoacacia)、麻栎(Quercus acutissima)、油松(Pinus tabulaeformis)和赤松(Pinus densiflora)为研究对象, 采用凋落物分解袋法及Illumina Miseq测序平台对细菌16S rDNA V4-V5区扩增产物进行双端测序, 分析了4种树种细根分解对细菌群落结构及多样性的影响。结果表明: (1) 4种植物细根分解速率差异显著, 阔叶树种分解速率显著高于针叶树种, 表现为刺槐>麻栎>油松>赤松。(2) 4个树种细菌序列操作分类单元(OTU)、观测到的物种数、Ace指数和系统发育多样性之间差异显著, 且阔叶树种刺槐和麻栎显著低于针叶树种赤松和油松。4种细根分解的细菌群落结构存在极显著差异。细根初始碳(C)含量、木质素:氮(N)和C:N对细菌群落结构的影响较大。(3)细菌群落相对丰度在5%以上的优势类群是变形菌门、放线菌门、拟杆菌门、酸杆菌门, 且变形菌门、酸杆菌门在4个树种之间差异显著, 特别是阔叶树种变形菌门显著高于针叶树种。在纲水平上, α-变形菌纲、β-变形菌纲、γ-变形菌纲、不明放线菌纲、鞘脂杆菌纲为主要的优势纲, 其中α-变形菌纲、不明放线菌纲在4个树种之间差异显著。(4) Pearson相关性分析表明, 细菌优势门和纲相对丰度受到凋落物初始化学性质的影响, 特别是变形菌门和α-变形菌纲; 变形菌门和α-变形菌纲相对丰度与细根分解速率显著正相关。冗余分析结果也显示, 细根初始N、磷(P)含量和木质素含量对细菌群落结构的影响较大。研究结果有助于理解细菌群落结构和多样性对森林生态系统细根凋落物分解的影响。     

基于T-RFLP方法的连栽杉木根际土壤细菌群落变化研究

运用末端限制性片段长度多态性技术(T-RFLP),研究福建省尤溪国有林场的多代连栽杉木根际土壤细菌群落变化特征。结果表明:杉木多代连栽后根际微生态失衡,表现为碳循环菌和氮循环菌等有益菌数量减少,病原菌数量增加。在不同代数杉木土壤中,4种内切酶消化后产生的末端限制性片段(T-RFs)数量具有显著差异,第一代杉木(first Chinese fir rotation plantation,FCP)最高,第二代杉木(second Chinese fir rotation plantation,SCP)次之,第三代杉木(third Chinese fir rotation plantation,TCP)最少。土壤理化性质结果表明连栽导致土壤养分逐代降低,除土壤碳氮比与细菌群落多样性呈显著负相关外,土壤养分含量指标与细菌群落多样性呈显著正相关。T-RFLP实验共鉴定出细菌门类12门,其中厚壁菌门、蓝藻门、放线菌门和变形菌门是主要优势菌群。随栽植代数的增加,变形菌门细菌比例递增,而厚壁菌门细菌比例递减。土壤细菌群落多样性指数,表现为随栽植代数增长而减少,呈现FCPSCPTCP趋势,与T-RFs片段数量变化趋势基本一致,表明多代连栽降低了杉木根际土壤细菌群落多样性。依据功能性不同,可将鉴定出的细菌划分为5类:碳循环功能菌、硫循环功能菌、氮循环功能菌、纤维降解菌及病原菌。连栽导致碳循环菌和氮循环菌相对含量降低,硫循环菌和纤维降解菌相对含量提高,病原菌相对含量随栽植代数增加而上升。     

Shifts in Microbial Community Composition Following Surface Application of Dredged River Sediments

Sediment input to the Illinois River has drastically decreased river depth and reduced habitats for aquatic organisms. Dredging is being used to remove sediment from the Illinois River, and the dredged sediment is being applied to the surface of a brownfield site in Chicago with the goal of revegetating the site. In order to determine the effects of this drastic habitat change on sediment microbial communities, we examined sediment physical, chemical, and microbial characteristics at the time of sediment application to the soil surface as well as 1 and 2 years after application. Microbial community biomass was determined by measurement of lipid phosphate. Microbial community composition was assessed using phospholipid fatty acid (PLFA) analysis, terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes, and clone library sequencing of 16S rRNA genes. Results indicated that the moisture content, organic carbon, and total nitrogen content of the sediment all decreased over time. Total microbial biomass did not change over the course of the study, but there were significant changes in the composition of the microbial communities. PLFA analysis revealed relative increases in fungi, actinomycetes, and Gram positive bacteria. T-RFLP analysis indicated a significant shift in bacterial community composition within 1 year of application, and clone library analysis revealed relative increases in Proteobacteria, Gemmatimonadetes, and Bacteriodetes and relative decreases in Acidobacteria, Spirochaetes, and Planctomycetes. These results provide insight into microbial community shifts following land application of dredged sediment.     

珠江浮游真核微型生物分子多样性及其与水环境的关系

文章分别在丰水期和枯水期于珠江广州段和西江广东段43个样点采集水样, 基于末端限制性长度多态性分析, 研究了珠三角地区珠江水体的浮游真核微型生物的分子多样性及其群落结构和水体理化因子的关系。结果表明, 西江广东段及珠江广州段水体氮和磷严重超标, 水质状况堪忧。枯水期样本浮游真核微型生物香农威尔多样性指数普遍高于丰水期样本, 西江广东段样本浮游真核微型生物多样性指数普遍高于珠江广州段样本。不同水期, 不同区域的浮游真核微型生物群落结构均存在显著差异。珠江样点的浮游真核微型生物群落结构均与化学需氧量、高锰酸盐指数、氨氮、总氮、总磷高度相关; 但不同水期、不同区域的浮游真核微型生物群落结构与理化因子相关系数有所差异。此外, 分别筛选出了1个、8个末端限制性片段代表了潜在的敏感(Cystobasidium sp.或Protostelium nocturnum)、耐污(Acanthamoeba hatchetti、Babesia bicornis、Blastocystis sp.、Botryosphaerella sudetica、Candida caryicola、Coccomyxa simplex、Cryptomonas ovata、Filos agilis、Stenophora robusta、Sulfonecta uniserialis、Theileria sp.等)物种/类群。     

Comparison of Bacterial Communities in New England Sphagnum Bogs Using Terminal Restriction Fragment Length Polymorphism (T-RFLP)

Wetlands are major sources of carbon dioxide, methane, and other greenhouse gases released during microbial degradation. Despite the fact that decomposition is mainly driven by bacteria and fungi, little is known about the taxonomic diversity of bacterial communities in wetlands, particularly Sphagnum bogs. To explore bacterial community composition, 24 bogs in Vermont and Massachusetts were censused for bacterial diversity at the surface (oxic) and 1 m (anoxic) regions. Bacterial diversity was characterized by a terminal restriction fragment length (T-RFLP) fingerprinting technique and a cloning strategy that targeted the 16S rRNA gene. T-RFLP analysis revealed a high level of diversity, and a canonical correspondence analysis demonstrated marked similarity among bogs, but consistent differences between surface and subsurface assemblages. 16S rDNA sequences derived from one of the sites showed high numbers of clones belonging to the Deltaproteobacteria group. Several other phyla were represented, as well as two Candidate Division-level taxonomic groups. These data suggest that bog microbial communities are complex, possibly stratified, and similar among multiple sites.     

Mineralization of glucose and lignocellulose by four arctic freshwater sediments in response to nutrient enrichment.

Microbial biomass and activity were examined in four different arctic sediments: littoral lake sediment and profundal lake sediment from Toolik Lake, Alaska, thaw pond sediment, and eroding river bank peat. The thaw pond sediment had the largest viable microbial biomass, while the profundal sediment had the smallest. Rates of glucose or acetate incorporation into lipids, glucose mineralization, and lignocellulose mineralization (all normalized per unit of biomass) were highest in the river peat sample, however. The kinetics of glucose mineralization in the profundal sediment were very different from those in the other three samples: although the initial rate of mineralization was five times lower than that in the peat and two times lower than that in the littoral and thaw pond sediments, the maximum amount of 14CO2 evolved from [14C]glucose eventually equaled that in the peat and exceeded that in the littoral and thaw pond sediments by 2.0 and 3.5 times, respectively. Carex aquatilis [14C-cellulose]- and [14C-lignin]lignocellulose mineralization rates in the profundal sediment equaled or exceeded those in the littoral sediment after 16 and 46 days, but the pattern of nutrient limitation differed: the profundal sediment was the only one sampled that exhibited nitrogen limitation, while the other three sediments appeared to be limited primarily by phosphorus. The addition of nitrogen and phosphorus together had no cumulative effects on lignocellulose mineralization. When the rates of mineralization or incorporation of glucose are compared with those of lignocellulose, the results of this study indicate that profundal sediment communities may be better able to utilize the more recalcitrant substrates relative to the labile substrates than microbial communities from sediments rich in detritus and standing macrophytes.     

Mineralization of glucose and lignocellulose by four arctic freshwater sediments in response to nutrient enrichment.

Microbial biomass and activity were examined in four different arctic sediments: littoral lake sediment and profundal lake sediment from Toolik Lake, Alaska, thaw pond sediment, and eroding river bank peat. The thaw pond sediment had the largest viable microbial biomass, while the profundal sediment had the smallest. Rates of glucose or acetate incorporation into lipids, glucose mineralization, and lignocellulose mineralization (all normalized per unit of biomass) were highest in the river peat sample, however. The kinetics of glucose mineralization in the profundal sediment were very different from those in the other three samples: although the initial rate of mineralization was five times lower than that in the peat and two times lower than that in the littoral and thaw pond sediments, the maximum amount of 14CO2 evolved from [14C]glucose eventually equaled that in the peat and exceeded that in the littoral and thaw pond sediments by 2.0 and 3.5 times, respectively. Carex aquatilis [14C-cellulose]- and [14C-lignin]lignocellulose mineralization rates in the profundal sediment equaled or exceeded those in the littoral sediment after 16 and 46 days, but the pattern of nutrient limitation differed: the profundal sediment was the only one sampled that exhibited nitrogen limitation, while the other three sediments appeared to be limited primarily by phosphorus. The addition of nitrogen and phosphorus together had no cumulative effects on lignocellulose mineralization. When the rates of mineralization or incorporation of glucose are compared with those of lignocellulose, the results of this study indicate that profundal sediment communities may be better able to utilize the more recalcitrant substrates relative to the labile substrates than microbial communities from sediments rich in detritus and standing macrophytes.     

海南东寨港红树林不同植被土壤微生物群落结构比较

【目的】比较不同植被下红树林土壤细菌和古菌的多样性及群落结构,认识红树林土壤微生物资源多样性。【方法】直接提取红树林土壤总DNA,采用细菌通用引物27F/1492R和古菌通用引物Arch21F/Arch958R进行PCR扩增,构建细菌和古菌16S rRNA基因文库,对海南东寨港自然保护区秋茄林、无瓣海桑林和无红树林裸滩土壤的细菌和古菌多样性和群落结构进行分析和比较。【结果】3种土壤样品的细菌类群包括变形细菌门(Proteobacteria)等16个类群,其中变形细菌门(Proteobacteria)与绿屈挠菌门(Chloroflexi)是优势类群;古菌包括6个嗜泉古菌界(Crenarchaeota)类群和7个广域古菌界(Euryarchaeota)类群,分别以Marine Benthic Group C、Marine Benthic Group D为优势类群。多样性指数(H’)和物种丰富度指数(Schao1)表明,本地种秋茄林下土壤细菌和古菌的多样性指数最高,外来种无瓣海桑显著低于秋茄林,甚至明显低于相邻无红树林裸滩沉积物;不同植被下土壤细菌和古菌群落结构存在显著差异,秋茄林土壤微生物群落结构和无红树林裸滩沉积物更相似。【结论】红树林土壤微生物类群丰富,不同植被下土壤细菌和古菌多样性和群落结构存在显著差异。     

Community Structure Analyses Are More Sensitive to Differences in Soil Bacterial Communities than Anonymous Diversity Indices

Changes in the diversity and structure of soil microbial communities may offer a key to understanding the impact of environmental factors on soil quality in agriculturally managed systems. Twenty-five years of biodynamic, bio-organic, or conventional management in the DOK long-term experiment in Switzerland significantly altered soil bacterial community structures, as assessed by terminal restriction fragment length polymorphism (T-RFLP) analysis. To evaluate these results, the relation between bacterial diversity and bacterial community structures and their discrimination potential were investigated by sequence and T-RFLP analyses of 1,904 bacterial 16S rRNA gene clones derived from the DOK soils. Standard anonymous diversity indices such as Shannon, Chao1, and ACE or rarefaction analysis did not allow detection of management-dependent influences on the soil bacterial community. Bacterial community structures determined by sequence and T-RFLP analyses of the three gene libraries substantiated changes previously observed by soil bacterial community level T-RFLP profiling. This supported the value of high-throughput monitoring tools such as T-RFLP analysis for assessment of differences in soil microbial communities. The gene library approach also allowed identification of potential management-specific indicator taxa, which were derived from nine different bacterial phyla. These results clearly demonstrate the advantages of community structure analyses over those based on anonymous diversity indices when analyzing complex soil microbial communities.     

Microbial diversity of topographical gradient profiles in Fushan forest soils of Taiwan

To evaluate the microbial diversity of Fushan forest soils, the variation of soil properties, microbial populations, and soil DNA with soil depth in three sites of different altitude were analyzed. Microbial population, moisture content, total organic carbon (C_org), and total nitrogen (N_tot) decreased with increasing soil depth. The valley site had the lowest microbial populations among the three tested sites due to the low organic matter content. Bacterial population was the highest among the microbial populations. The ratios of cellulolytic microbes to the total bacteria in organic layers were high, implying their roles in the carbon cycle. The microbial biomass carbon (C_mic) and nitrogen (N_mic) contents ranged from 130.5 to 564.1 μg g⁻¹ and from 16.7 to 95.4 μg g⁻¹, respectively. The valley had the lowest C_mic and N_mic. The organic layer had the highest C_mic and N_mic and decreased with soil depth. Analysis using denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR) amplicons of 16S rDNA showed that the bacterial diversity of the three sites were very similar to each other in the major bands, and the variation was in the minor bands. However, the patterns in PCR-DGGE profile through gradient horizons were different, indicating the prevalence of specific microbes at different horizons. These results suggest that the microbial diversity in the deeper horizons is not simply the diluted analogs of the surface soils and that some microbes dominate only in the deeper horizons. Topography influenced the quantity and diversity of microbial populations.