藻际环境微生态结构与功能的研究进展

藻际环境是以藻类分泌物为骨架构成的微型生态结构,包含多样的生物和非生物,主要是微生物、胞外多糖、蛋白质和核酸等物质.藻际环境为复杂的藻菌互动提供平台,也为藻际系统的物质代谢、能量流动和信息交流提供基础.藻际环境不仅可以形成特殊的生态位,而且藻菌作用对多种生源要素循环起到了关键的作用;同时,藻际多糖的沉降为碳封存做出了重...     

藻际环境中微生物胞间通讯行为及作用

藻际环境中,微生物通过营养物质交换和活性物质释放相互作用,进而引发共生、竞争或合作等行为.结合环境条件的影响,藻际环境一般具有稳定而多样的微生态结构.以上行为发生的基础是以信号分子为媒介的微生物胞间通讯作用.本文系统综述了藻际环境的特征、藻际胞间通讯行为以及藻际胞间信号分子的类别与作用机制.特别针对痕量信号分子特性,结...     

分解者在生态系统物质循环中的作用

在生态系统的物质循环中,分解者起着关键的作用,分解者需分泌胞外酶水解动植物残骸中的大分子有机物质,然后吸收水解产物,作为营养物质,在细胞内氧化分解,最终将有机物变成无机物。     

非致病微生物在植物—病原菌协同进化中的作用

非致病微生物在植物－病原菌协同进化中的作用单卫星（西北农业大学植保系,陕西杨陵７１２１００）ＴｈｅＲｏｌｅｏｆＮｏｎ－ｐａｔｈｏｇｅｎｉｃＭｉｃｒｏｏｒｇａｎｉｓｍｓｉｎＰｌａｎｔ－ｐａｔｈｏｇｅｎＣｏｅｖｏｌｕｔｉｏｎ￥ＳｈａｎＷｅｉｘｉｎｇ（Ｄｅｐａｒｔ－ｍｅｎｔｏｆＰｌａｎｔＰｒｏｔｅｃｔｉｏｎ,ＮｏｒｔｈｗｅｓｔｅｒｎＡｇｒｉｃｕｌｔｕｒａｌＵｎｉｖｅｒｓｉｔｙ,Ｙａｎｇｌｉｎｇ,Ｓｈａａｎｘｉ７１２１００）．ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＥｃｏｌｏｇｙ,１９９３,１２（６）,５４－５９．Ｉｎｖｉｅｗｏｆｐｒｅｓｅｎｔｐｒｏｂｌｅｍｓａｓｓｏｃｉａｔｅｄｗｉｔｈｐｌａｎｔｄｉｓｅａｓｅｃｏｎｔｒｏｌ,ｃｏｕｐｌｅｄｗｉｔｈｒｅｃｅｎｔａｄｖａｎｃｅｓｉｎｂｉｏｌｏｇ－ｉｃａｌｃｏｎｔｒｏｌｏｆｐｌａｎｔｄｉｓｅａｓｅｓａｎｄｐｌａｎｔ－ｐａｔｈｏｇｅｎｉｎｔｅｒａｃｔｉｏｎｓ,ｔｈｅａｕｔｈｏｒｐｏｉｎｔｅｄｏｕｔｔｈｅｉｍｐｏｒｔａｎｃｅｏｆｎｏｎ－ｐａｔｈｏｇｅｎｉｃｍｉｃｒｏｏｒｇａｎｉｓｍｓｉｎｈａｂｉｔｉｎｇｐｌａｎｔｓｕｒｆａｃｅｓｉｎｒｅｇｕｌａｔｉｏｎｏｆｐｌａｎｔ－ｐａｔｈｏｇｅ     

海带藻际微生物抗菌活性及其多样性的初步研究

从浙江台州海域健康海带、病烂海带(Laminaria japonica)及其周围海水中分离纯化海带藻际微生物, 利用双层琼脂扩散法对获得的菌株进行抗菌活性筛选, 比较活性菌株与来源的相关性, 并对具有抗菌活性的菌株进行16S rRNA系统发生学分析。结果显示, 在分离的143株海带藻际微生物中, 有42株细菌具有抗菌活性, 其中来源于健康海带和海水的活性菌株比例(35%和29%)大于来源于病烂海带的细菌(23%)。对其中16株具有广谱抗菌活性的菌株进行的16S rRNA系统发生学分析显示, 分别属于Pseudoalteromonas、Rahnella、Donghaeana、Bacillus和Exiguobacterium 5个属。为从藻际微环境的微生物多样性入手了解海带病烂机制以及寻找新的抗菌药物提供研究材料。       

藻际环境中胞外聚合物的研究进展

微藻向细胞周围释放营养物质而形成了独特的藻际微环境,吸引了大量细菌的定殖。藻际环境中藻菌关系错综复杂,其间充斥着多样的物质交换与信息交流。以胞外聚合物(extracellularpolymeric substances,EPS)为代表的有机质在其中起着纽带作用。微藻和细菌都可以产生EPS,其过程受多种因素的调节。EPS在藻际环境中具有重要的生态功能,包括参与生物被膜(biofilm)的形成,影响藻菌共生关系的建立以及调节藻际微生物群落组成等。此外,EPS中的一大类别透明胞外聚合物颗粒(transparent exopolymer particles,TEP)还介导了海洋溶解有机碳向颗粒有机碳的转化,参与了海洋碳循环过程。本文以EPS的产生、组成以及对碳转化的影响为重点,综述了其在藻际生态位(Niche)中的生态功能,以期为深入理解藻际环境中的有机质特征和藻菌共生关系提供理论依据。     

溶磷微生物在土壤磷循环中的作用研究进展

磷是生物分子中的重要元素,是陆地生态系统初级生产的主要限制因子之一。全球粮食需求的增加和现代农业对磷肥的消耗导致集约农田中磷的过量输入,进而引起土壤磷流失的增加和地表水的持续富营养化。溶磷微生物(phosphate solubilizing microorganisms, PSMs)被认为是可以提高农业生产力的生态友好型肥料,在改善土壤肥力方面有重要意义。全面和深入理解PSMs功能及其在磷的土壤生物化学转化过程中的作用,对提高土壤磷有效性有至关重要的作用。本文系统综述了PSMs的种类和分布多样性,主要参与微生物磷循环的功能基因,以及PSMs如何参与土壤磷循环和这些过程背后的反应机制,以便更好地认识PSMs能力及其在土壤磷循环中的作用,以便于在未来的应用中发挥更大的潜力。     

若干技术在根际微生物研究中的应用

根际微生物是指植物根表及近根土壤中的微生物。根际微生物的研究对于微生物生态学、植物生态学及工业生物技术开发均具有十分重要的意义。为了进行更全面的研究以应对根际微生物研究所面临的复杂挑战,需要将各种生物学研究方法结合起来使用。综述了目前国内外应用较广泛的基于分子生物学的根际微生物研究方法,并对若干主要方法进行了横向比较,重点论述了结合高通量测序技术和基因芯片技术的根际微生物研究方法的新进展,并对相关技术的应用现状及其未来应用前景进行了综述。     

不同生长期核桃根际微生物群落特征

植物根系能够在复杂的土壤环境中招募对自身有益的微生物构建根际微生物群落。为了探明不同生长期核桃根际微生物群落的特征,本研究采集了核桃萌芽期、开花期和结果期的根际和非根际土壤样品,进行了高通量测序、差异物种分析、功能分析和微生物生态网络相关性分析。结果表明：核桃根际在不同生长期的优势种群存在一定程度的差异,萌芽期相对丰度显著增加的菌属有芽孢杆菌属(Bacillus)和unclassified Fungi,开花期有unclassified Chloroplast、枝孢属(Cladosporium)、链格孢属(Alternaria)和无茎真菌属(Acaulium),结果期有unclassified Micrococcaceae、假单胞菌属(Pseudomonas)、链霉菌属(Streptomyces)、赤霉菌属(Gibberella)和被孢霉属(Mortierella);其中,芽孢杆菌属(3.0%)、unclassified Chloroplast(4.5%)、假单胞菌属(17.9%)分别为萌芽期、开花期和结果期主要有益菌属。同时,不同生长期的根际土壤细菌和真菌群落结构存在显著差异(P<...     

微生物耐砷机理及其在砷地球化学循环中的作用北大核心CSCD

砷是一种无处不在的有毒类金属,其强致癌性引起了人类的广泛关注。在自然环境中,砷的转化存在物理化学过程和生物过程,其中微生物介导的砷转化是环境砷行为的主要影响因素。微生物的耐砷特性与砷吸收、氧化还原、甲基化、区隔化和外排等过程密切相关。砷在微生物体内的转运转化主要与砷解毒有关,但某些微生物可利用氧化还原过程产生的能量以维持其生长需求。本文综述了微生物介导的砷吸收、转化、区隔化和外排机制,这对阐明砷的地球化学循环过程及指导砷污染土壤和水体修复、阻控农作物砷吸收等方面具有重要意义。     

Deciphering host migrations and origins by means of their microbes

Mitochondrial DNA and microsatellite sequences are powerful genetic markers for inferring the genealogy and the population genetic structure of animals but they have only limited resolution for organisms that display low genetic variability due to recent strong bottlenecks. An alternative source of data for deciphering migrations and origins in genetically uniform hosts can be provided by some of their microbes, if their evolutionary history correlates closely with that of the host. In this review, we first discuss how a variety of viruses, and the bacterium Helicobacter pylori, can be used as genetic tracers for one of the most intensively studied species, Homo sapiens. Then, we review statistical problems and limitations that affect the calculation of particular population genetic parameters for these microbes, such as mutation rates, with particular emphasis on the effects of recombination, selection and mode of transmission. Finally, we extend the discussion to other host-parasite systems and advocate the adoption of an integrative approach to both sampling and analysis.     

Shaping the phycosphere: Analysis of the EPS in diatom-bacterial co-cultures

The phycosphere is a unique niche that fosters complex interactions between microalgae and associated bacteria. The formation of this extracellular environment, and the associated bacterial biodiversity, is heavily influenced by the secretion of extracellular polymers, primarily driven by phototrophic organisms. The exopolysaccharides (EPS) represent the largest fraction of the microalgae-derived exudates, which can be specifically used by heterotrophic bacteria as substrates for metabolic processes. Furthermore, it has been proposed that bacteria and their extracellular factors play a role in both the release and composition of the EPS. In this study, two model microorganisms, the diatom Phaeodactylum tricornutum CCAP 1055/15 and the bacterium Pseudoalteromonas haloplanktis TAC125, were co-cultured in a dual system to assess how their interactions modify the phycosphere chemical composition by analyzing the EPS monosaccharide profile released in the culture media by the two partners. We demonstrate that microalgal–bacterial interactions in this simplified model significantly influenced the architecture of their extracellular environment. We observed that the composition of the exo-environment, as described by the EPS monosaccharide profiles, varied under different culture conditions and times of incubation. This study reports an initial characterization of the molecular modifications occurring in the extracellular environment surrounding two relevant representatives of marine systems.     

5株北极微藻藻际环境的细菌多样性

对5株北极微藻,如脆杆藻(Fragilariopsis sp.)、微单胞藻(Micromonas sp.)、四棘藻(Attheya septentrionalis)、海链藻(Thalassiosira sp.)和小球藻(Chlorella sp.)的不同生长时期的粘附细菌和游离细菌的16S rRNA基因进行PCR-DGGE分析,研究藻际环境的细菌多样性。结果表明,5株微藻具有不同的藻际微生物群落结构组成,其中微单胞藻、脆杆藻、四棘藻和海链藻的藻际细菌主要由Cyanobacteria(藻蓝细菌)、α-Proteobacteria(α-变形菌纲)和γ-Proteobacteria(γ-变形菌纲)组成,仅微单胞藻和脆杆藻检测出CFB(Cytophaga-Flexibacter-Bacteroides,噬纤维菌-屈挠杆菌-拟杆菌)。小球藻由Cyanobacteria、CFB、α-Proteobacteria和β-Proteobacteria(β-变形菌纲)组成。微单胞藻的藻际菌群结构稳定,不同生长时期的游离细菌和粘附细菌组成差异不明显。3株硅藻-脆杆藻、四棘藻和海链藻的游离细菌主要由γ-Proteobacteria组成,小球藻的游离细菌主要为β-Proteobacteria,而5株微藻的粘附细菌主要由Cyanobacteria组成。从DGGE图谱来看,在脆杆藻生长的延滞期、指数期和稳定期,其藻际游离细菌和粘附细菌的16S rRNA基因扩增条带数量和位置均有明显差异,但优势扩增条带较稳定;其他4株藻粘附细菌和游离细菌的扩增条带比较稳定,说明藻际关联菌群结构较稳定。藻菌种间特异性关系为不同微藻藻株提供了重要的线索,同时也带来更多的隐藏在藻际环境中的信息。     

光降解在凋落物分解中的作用

近年来,越来越多的研究者认识到光降解可能在凋落物分解中发挥着重要作用.本文对光降解的作用机制,光降解在碳循环、养分循环中的作用,光降解与微生物分解的关系,以及影响光降解的因素进行了综述.光降解对凋落物分解过程同时具有正效应和负效应,正效应指光降解通过氧化有机质,或是改变凋落物自身理化性质使其更易淋溶和分解,负效应指高光辐射对分解者产生不利影响从而押制微生物分解.在光降解过程中光化学矿化产生CO2是生态系统碳流失的主要机制.除紫外光外,可见光中的蓝、绿光波段也对凋落物的降解产生影响.光降解作用的大小受到水分状况、凋落物化学性质和凋落物的暴露面积的影响.最后,讨论了该领域有待深入研究的方向,指出今后应当重点对光降解研究方法,光降解与环境因子的交互作用,光降解作用的空间差异,光降解与微生物分解的相互关系及其作用强度进行研究.     

Characterisation of antagonistic soil microbes against Rhizoctonia spp. and Sclerotium hydrophilum

Rhizoctonia solani, R. oryzae-sativae and Sclerotium hydrophilum are responsible for sheath diseases of rice. Soil treatment measures with antagonist microbes have produced good results against various soil-borne fungi. The objective of this study included to find out the potential antagonist microbes from the paddy field soil. Ten different soil samples were collected from the disease-prone area of paddy field soil. Antagonist microbes were identified by 16S rRNA sequence analysis. Subsequent screening of antagonist microbes yield B. subtilis B37 and P. aeruginosa B258 as the potential antagonist microbes to control sheath diseases of rice in Myanmar. Bacillus subtilis strains induced the competition between antagonist and the tested fungi at the margin of the bacterial growth itself. However, P. aeruginosa induced the competition at a long range formed by the antibiotic of antagonist microbe. Bacillus subtilis B37 and P. aeruginosa B258 could be applicable in the control strategy of causal agents of rice sheath diseases in Myanmar.     

塔玛亚历山大藻藻际细菌溶藻过程

海洋微藻在生长过程中向周围环境分泌多种胞外产物,形成细菌自由生长的藻际环境,藻际细菌对微藻的生长有一定的调控作用。在指数生长期的塔玛亚历山大藻培养液中加入φ为1%的2216E培养基,在加入2216E后16h内藻细胞全部裂解。用数码显微镜记录了藻细胞形态变化,分别用DAPI法和荧光模拟底物法测定了细菌数量、胞外酶活性变化,结果表明:在溶藻过程中细菌数量、胞外酶活性在第6小时到第10小时增加了50～100倍。塔玛亚历山大藻藻际细菌主要分布在藻细胞表面,其群落结构改变和数量剧增是溶藻的主要原因,细菌分泌的β-葡萄糖苷酶和几丁质酶可能在溶藻过程中起重要作用。     

Quorum Sensing Is a Language of Chemical Signals and Plays an Ecological Role in Algal-Bacterial Interactions

Algae are ubiquitous in the marine environment, and the ways in which they interact with bacteria are of particular interest in the field of marine ecology. The interactions between primary producers and bacteria impact the physiology of both partners, alter the chemistry of their environment, and shape microbial diversity. Although algal-bacterial interactions are well known and studied, information regarding the chemical-ecological role of this relationship remains limited, particularly with respect to quorum sensing (QS), which is a system of stimuli and response correlated to population density. In the microbial biosphere, QS is pivotal in driving community structure and regulating behavioral ecology, including biofilm formation, virulence, antibiotic resistance, swarming motility, and secondary metabolite production. Many marine habitats, such as the phycosphere, harbor diverse populations of microorganisms and various signal languages (such as QS-based autoinducers). QS-mediated interactions widely influence algal-bacterial symbiotic relationships, which in turn determine community organization, population structure, and ecosystem functioning. Understanding infochemicals-mediated ecological processes may shed light on the symbiotic interactions between algae host and associated microbes. In this review, we summarize current achievements about how QS modulates microbial behavior, affects symbiotic relationships, and regulates phytoplankton chemical-ecological processes. Additionally, we present an overview of QS-modulated co-evolutionary relationships between algae and bacterioplankton, and consider the potential applications and future perspectives of QS.