Comparison on bacterial community of rhizosphere and bulk soil of poplar plantation based on pyrosequencing北大核心CSCD

By the 454 pyrosequencing technology, this research compared the bacterial communities in poplar plantation rhizosphere and bulk soil for an accurate understanding of bacterial community colonization in the two soil environments. The species annotation showed that rhizosphere soil contained 145 bacterial genera and bulk soil contained 141 bacterial genera, with 8 common genera shared by both at a relative abundance of more than 4%. The 8 genera in common were Acidobacterium GP1, Acidobacterium GP3, Acidobacterium GP6, Gemmatimonas, Bradyrhizobium, Burkholderia, Streptomyces and Acidobacterium GP4. The relative abundance of the same bacterial community was significantly different between rhizosphere and bulk soil environments. Alpha diversity analysis showed that the bacterial community diversity of rhizosphere soil was higher than that of bulk soil, but the difference was not significant. The results of bacterial communities sorting could reflect the variation of soil bacterial communities from rhizosphere to the bulk and the spatial variation among different sampling points, indicating a contribution of about 21.2% variance of bacterial communities by the effect of rhizosphere. Beta diversity analysis showed great difference between rhizosphere and bulk soil samples in bacterial community composition. There were 15 genera specific to rhizosphere soil and 11 to bulk soil. The abundance of 23 genera, mainly cellulose degrading bacteria and nitrogen-fixing bacteria, changed significantly. Selectivity of root to rhizosphere microorganisms is an important mechanism leading to significant differences in the rhizosphere microbial community composition and structure, which may significantly impact the carbon and nitrogen cycles of the root-soil interface.     

2种入侵植物对根际土壤微生物种群及代谢的影响

选取2种入侵植物（一年蓬Annual Fleabane及加拿大蓬Erigeron Canadensis）及本土植物（艾蒿Artemisia argyi）的根际土壤微生物种群为研究对象,以分析不同根际土壤微生物种群的数量及测定根际土壤微生物酶活的活性为切入点来探析入侵植物对土壤微生物的影响及其响应机制。结果显示：2种入侵植物显著增加了其根际土壤中的细菌的数量,而显著抑制了真菌与放线菌的数量。另外,入侵植物一年蓬显著抑制其根际土壤中纤维素酶的活性,而3种植物的根际土壤硝酸还原酶活性无显著差异。入侵植物对其他3种土壤酶（即转化酶、脲酶及酸性磷酸酶）活性的影响却呈现出截然相反的影响,即一年蓬显著增加了3种根际土壤酶的活性,而加拿大蓬却显著减少了3种根际土壤酶的活性。导致这种现象的原因可能是不同入侵植物的根系释放不同的化学物质进而对土壤微生物的数量和活性造成不同的影响。     

铜陵矿集区土壤中污染元素对微生物特性的影响研究

通过铜陵矿集区土壤中重金属污染元素含量与土壤中微生物生物量之间的对应关系,研究其环境效应。采集深度为20cm的土样,分别制备不同微生物的培养基以期对土壤中的微生物进行分离计数,细菌和放线菌采用稀释平板涂布法计数,高铁还原菌采用最大或然数法计数。研究结果表明,铜陵矿集区土壤中As、Au、Cd、Zn、Cu、Pb元素含量与土壤中细菌、放线菌、高铁还原菌数量之间的相关关系为：As、Au、Zn、Cu与细菌和放线菌,Cd、Pb与放线菌的含量呈负相关关系,指示了土壤中高浓度污染元素对微生物的抑制作用;Cd、Pb与细菌,Cd、Zn与高铁还原菌的含量呈正相关关系,反映部分微生物受污染元素的胁迫已产生了耐受性;Au、Pb、As与高铁还原菌数量的关系不明显。通过实验数据发现,微生物在重金属含量高的区域和含量低的区域的数量下降了大约2～3个数量级,有些区域微生物数量下降了约50%。矿集区土壤中三种菌种对污染元素的敏感程度不同,其敏感程度依次是：放线菌〉细菌〉高铁还原菌。矿集区部分土壤中,细菌、高铁还原菌由于其本身的耐受性或由于受胁迫而产生了耐受性,对Cd、Zn、Pb等三种重金属污染元素的抗性水平较高,具有作为土壤重金属元素污染修复微生物菌种的潜力。     

南亚热带不同植被根际微生物数量与根际土壤养分状况

研究了包括尾叶桉、广东凤丫蕨、柳叶竹、大叶相思、青皮、木荷、湿地松在内的7种南亚热带不同植物植被下土壤根际微生物与根际养分状况及其相关关系。结果表明,根际环境对细菌有明显的正效应,对放线菌和真菌有正、负两方面的影响,但对根际微生物总量具有根际效应明显;在南亚热带森林生态系统中.在植物的某些生长季节,微生物的根际效应与土壤养分的根际效应一致     

返青前后草地早熟禾草坪根际微生物区系动态

根际是土壤-植物生态系统物质及能量交换的活跃界面,根际微生物不仅直接影响植物对水分、养分的吸收,而且也同时影响植物对不良环境的抵抗能力。利用选择性培养基对草地早熟禾(PoapratensisL.)返青前后根际与非根际的细菌、真菌以及放线菌类群进行分离测数,拟从根际及非根际土壤微生物区系动态变化方面来阐述草地早熟禾返青前后其根际微生态的变化规律。结果表明:(1)草地早熟禾草坪的返青后,根际及非根际细菌、真菌数量明显增加,但放线菌数量呈减少趋势;(2)无论返青前后或者根际以及非根际,细菌的数量都占整个土壤微生物量的绝大部分,细菌数量的变化代表了整个微生物类群数量的变化趋势,使得草地早熟禾返青后根际土壤由"真菌型"向"细菌型"转化;(3)返青前后,各微生物类群都表现出明显的根际效应。     

Effect of rhizosphere on soil microbial community and pyrene biodegradation

To access the influence of a vegetation on soil microorganisms toward organic pollutant biogegration, this study examined the rhizospheric effects of four plant species (sudan grass, white clover, alfalfa, and fescue) on the soil microbial community and in-situ pyrene (PYR) biodegradation. The results indicated that the spiked PYR levels in soils decreased substantially compared to the control soil without planting. With equal planted densities, the efficiencies of PYR degradation in rhizosphere with sudan grass, white clover, alfalfa and fescue were 34.0%, 28.4%, 27.7%, and 9.9%, respectively. However, on the basis of equal root biomass the efficiencies were in order of white clover >> alfalfa > sudan > fescue. The increased PYR biodegradation was attributed to the enhanced bacterial population and activity induced by plant roots in the rhizosphere. Soil microbial species and biomasses were elucidated in terms of microbial phospholipid ester-linked fatty acid (PLFA) biomarkers. The principal component analysis (PCA) revealed significant changes in PLFA pattern in planted and non-planted soils spiked with PYR. Total PLFAs in planted soils were all higher than those in non-planted soils. PLFA assemblages indicated that bacteria were the primary PYR degrading microorganisms, and that Gram-positive bacteria exhibited higher tolerance to PYR than Gram-negative bacteria did.     

不同放牧梯度下草甸草原土壤微生物和酶活性研究

通过小区控制放牧实验,研究呼伦贝尔草甸草原不同放牧强度下草地土壤微生物和酶活性的变化。结果表明：不同处理土壤微生物数量表现为细菌〉放线菌〉真菌。不同土层土壤微生物总数不放牧处理大于放牧处理,0～30 cm土层土壤微生物生物量碳、氮含量在轻牧区较高,在中牧区较低。土壤脲酶和过氧化氢酶活性轻度放牧和中度放牧高于不放牧和重度放牧。土壤微生物数量、生物量、土壤蛋白酶和过氧化氢酶活性均随土壤深度的增加呈递减趋势。相关分析表明,土壤微生物数量、微生物生物量以及土壤酶活性相互之间密切相关,土壤微生物量N与细菌达到极显著正相关（P〈0.01）,与真菌和放线菌呈显著相关（P〈0.05）。土壤微生物量C与真菌达到极显著负相关（P〈0.01）,与放线菌呈显著负相关（P〈0.05）。土壤微生物数量、土壤微生物量N与转化酶、蛋白酶、过氧化氢酶活性呈显著或极显著正相关。土壤微生物量C与转化酶、蛋白酶、过氧化氢酶呈显著负相关（P〈0.05）。     

Microbial community and functional genes in the rhizosphere of alfalfa in crude oil-contaminated soil

A rhizobox system constructed with crude oil-contaminated soil was vegetated with alfalfa (Medicago sativa L.) to evaluate the rhizosphere effects on the soil microbial population and functional structure, and to explore the potential mechanisms by which plants enhance the removal of crude oil in soil. During the 80-day experiment, 31.6% of oil was removed from the adjacent rhizosphere (AR); this value was 27% and 53%higher than the percentage of oil removed from the far rhizosphere (FR) and from the non-rhizosphere (NR), respectively. The populations of heterotrophic bacteria and hydrocarbon-degrading bacteria were higher in the AR and FR than in the NR. However, the removal rate of crude oil was positively correlated with the proportion of hydrocarbon-degrading bacteria in the rhizosphere. In total, 796, 731, and 379 functional genes were detected by microarray in the AR, FR, and NR, respectively. Higher proportions of functional genes related to carbon degradation and organic remediation, were found in rhizosphere soil compared with NR soil, suggesting that the rhizosphere selectively increased the abundance of these specific functional genes. The increase in water-holding capacity and decrease in pH as well as salinity of the soil all followed the order of AR>FR>NR. Canonical component analysis showed that salinity was the most important environmental factor influencing the microbial functional structure in the rhizosphere and that salinity was negatively correlated with the abundance of carbon and organic degradation genes.     

Effect of rhizosphere on soil microbial community and in-situ pyrene biodegradation

To access the influence of a vegetation on soil microorganisms toward organic pollutant biogegration, this study examined the rhizospheric effects of four plant species (sudan grass, white clover, alfalfa, and fescue) on the soil microbial community and in-situ pyrene (PYR) biodegradation. The results indicated that the spiked PYR levels in soils decreased substantially compared to the control soil without planting. With equal planted densities, the efficiencies of PYR degradation in rhizosphere with sudan grass, white clover, alfalfa and fescue were 34.0%, 28.4%, 27.7%, and 9.9%, respectively. However, on the basis of equal root biomass the efficiencies were in order of white clover >> alfalfa > sudan > fescue. The increased PYR biodegradation was attributed to the enhanced bacterial population and activity induced by plant roots in the rhizosphere. Soil microbial species and biomasses were elucidated in terms of microbial phospholipid ester-linked fatty acid (PLFA) biomarkers. The principal component analysis (PCA) revealed significant changes in PLFA pattern in planted and non-planted soils spiked with PYR. Total PLFAs in planted soils were all higher than those in non-planted soils. PLFA assemblages indicated that bacteria were the primary PYR degrading microorganisms, and that Gram-positive bacteria exhibited higher tolerance to PYR than Gram-negative bacteria did.     

间作与接种AMF对连作土壤微生物群落结构与功能的影响

为了探明间作种植模式和接种AMF对连作土壤的影响,试验选取马铃薯连作10年土壤为基质,采用两因素随机区组盆栽实验设计,研究间作及接种AMF对连作土壤微生物群落结构及功能的影响。结果表明：在不同间作模式及AMF接种后,连作土壤微生物群落结构、功能均有不同程度的差异。间作调控后马铃薯｜｜玉米｜｜蚕豆处理土壤细菌比例最高,放线菌次之,真菌最低;Biolog Eco板平均颜色变化率（AWCD）比对照高36.77%。间作并接种AMF（Gloumus etunicatum）后,土壤微生物功能多样性增强,土壤真菌的比例上升,细菌、放线菌的比例下降;马铃薯｜｜蚕豆、马铃薯｜｜玉米｜｜蚕豆土壤孢子密度与其他处理有显著差异（P〈0.05）;马铃薯｜｜玉米｜｜蚕豆处理在培养96 h后的平均颜色变化率（AWCD）值比单作高48.96%。各处理土壤根际微生物群落在2种方式的调控下对碳水化合物、氨基酸碳源利用强度较高,对芳香化合物的利用能力较弱;调控后碳源利用类型开始从碳水化合物、胺类化合物向胺类化合物和多聚化合物利用类型转变。间作调控和AMF调控对土壤微生物群落功能多样性的增加可能存在一定的叠加效应。土壤微生物群落结构、功能多样性的变化是多种因子综合作用的结果。     

贵州喀斯特山区不同种植年限花椒根际土壤细菌群落结构特征研究

以贵州花江峡谷花椒(Zanthoxylum bungeamun)林为研究对象,采用16S rRNA高通量测序技术,分析种植5、10、20、30 a花椒根际土壤细菌群落结构和多样性特征,探讨不同种植年限花椒土壤理化因子对根际细菌群落分布的影响,为喀斯特石漠化地区花椒农业可持续发展提供有效的理论依据.结果表明,随着花椒种植...     

Impact of anaerobically treated and untreated (raw) distillery effluent irrigation on soil microflora, growth, total chlorophyll and protein contents of Phaseolus aureus L

Impact of distillery effluent (untreated and treated) irrigation on soil microflora of the pots used for growing Phaseolus aureus L. was investigated. The growth of the P. aureus plants as affected by distillery effluent irrigation was also evaluated. The irrigation of the pots by 1-10% distillery effluent (anaerobically treated) stimulated the growth of the soil microflora (increased number of bacteria, fungi and actinomycetes) and P. aureus plants (increased shoot and root lengths, biomass, chlorophyll and protein contents). Further, 15-20% distillery effluent (anaerobically treated) had toxic effect on soil micro flora as indicated by reduced number of bacteria, fungi and actinomycetes. Reduction in shoot, root, lengths, biomass, chlorophyll, protein contents of P. aureus was also observed when irrigated by 15-20% treated distillery effluent. All the concentrations of raw distillery effluent reduced the bacterial population. However, the treated distillery effluent concentrations <10% had stimulatory effect on fungal and actinomycetes population. However, raw effluent concentrations >5% reduced the same. Raw distillery effluent was more toxic to P. aureus than treated distillery effluent as concentrations >5%, had reduced the growth (shoot, root length and biomass) of the test plant. Raw distillery effluent had adverse effect to total chlorophyll contents and all the test concentrations reduced the total chlorophyll level. However, untreated (raw) distillery effluent stimulated the protein content initially. It has been concluded from-present study that lower concentrations of the raw distillery effluent (1-5%) and treated distillery effluent (1-10%) had stimulated the growth of P. aureus and soil microflora except soil bacteria (inhibited by all the concentration of the raw effluent). However, higher concentrations (raw effluent: 10-20%; treated effluent 15-20%) had toxicity to test parameters.     

除草剂苯噻草胺对水稻田土壤微生物种群的影响

以浙江大学华家池校区水稻土为材料,采用室内培养法,研究了不同浓度的外源除草剂苯噻草胺对水稻田土壤可培养微生物种群数量的影响.结果表明:土壤中各微生物类群对不同浓度的苯噻草胺具有各自不同的反应.苯噻草胺能刺激好氧细菌数量增加,但不利于真菌和放线菌的生长.低浓度苯噻草胺刺激水解发酵性细菌(AFB)、产氢产乙酸细菌(HPAB)和产甲烷细菌(MPB)数量的增加,但高浓度苯噻草胺却具有抑制性.在苯噻草胺施用第4周时可强烈刺激反硝化细菌(DNB)数量的增加.苯噻草胺也能刺激厌氧固氮菌(ANFB)数量增加,但这种刺激作用在第2周才出现,而且在培养后期消失.苯噻草胺的短期影响即急性毒性对土壤中可培养微生物的影响较小,比上一代除草剂丁草胺相对安全.图2表1参15     

外来植物紫茎泽兰入侵对根际土壤有益功能细菌群、酶活性和肥力的影响

通过对紫茎泽兰不同入侵阶段下的实地采样,分析了外来入侵植物紫茎泽兰对入侵地根际土壤有益微生物菌群和土壤酶活性以及肥力的影响。发现除了全磷、全钾以外,重度入侵土壤的功能菌数量、酶活性、土壤肥力都要显著高于其它土壤区系。根际土中有机磷细菌差异最显著,其重度入侵土中的含量是轻度入侵土中含量的3.0倍,是当地植物土中含量的1.8倍,是空白地区含量的22.2倍。同时,土壤微生物类群、土壤酶活与土壤肥力的相关分析表明,它们之间存在显著相关关系,自生固氮菌与全氮相关性最明显,为0.922。外来植物对入侵地的影响是其入侵力和生态系统可入侵性的重要组成部分,紫茎泽兰入侵提高了土壤功能菌种群和土壤酶活,从而使土壤肥力也发生了相应的变化,这可能促进其养分转化吸收,提高种群竞争力。本文为紫茎泽兰成功入侵的土壤微生物学机制提供理论依据。     

铜陵新桥矿区土壤中耐Cu微生物的筛选研究

选择安徽铜陵新桥矿区富Cu的污染土壤,充分利用微生物受自然环境重金属胁迫而产生耐性这一特点,进行土壤中耐Cu微生物的筛选研究。实验过程中分别配制三种不同的培养基,细菌、真菌和放线菌培养基。在水浴恒温振荡器中对土壤中耐受重金属的微生物进行驯化,将得到的对cu2＋耐受性最高的液体培养基作为菌源,在琼脂平板培养基上进行划线分离,并将得到的纯菌株在光学显微镜下进行形态观察,菌种经试管斜面富集培养后保存在4℃冰箱中以便后续使用。研究发现,土样中细菌和真菌对cu的耐受性低,最高耐受质量浓度分别只达到500mg·L-1和1100mg·L-1。而放线菌表现出cu高耐受性,分离得到的放线菌耐受Cu的质量浓度最高达到10000mg·L-1,初步鉴定该放线菌株为链霉菌属。该放线菌菌种可能同时对Cu有吸附降解特性,具有成为污染土壤生物治理的高效耐受吸附菌种的潜力巨大。     

铝对荞麦和金荞麦根际土壤微生物及酶活性的影响

以两种耐锅性不同蓼科荞麦属植物荞麦和金荞麦为材料,通过土培盆栽试验,比较研究其根际土壤微生态对铝胁迫反应的差异.结果表明,一定质量分数的Al对荞麦和金荞麦根际土壤绌菌具有显著刺激效应,对金荞麦的影响更大,但Al质量分数过高,对细菌的刺激效应明显减弱,甚至产生抑制作用,荞麦和金荞麦根际土壤真菌数量均随着Al质量分数的升高而明显增加,荞麦根际土壤真菌增加幅度更为显著,Al胁迫下二者根际放线菌数量的变化亦表现出一定的差异;Al胁迫下,养麦和金荞麦根际土壤氨化细菌、硝化绌菌、反硝化细菌等氮素生理群微生物的变化趋势亦显示出明显差异,整体上荞麦根际土壤细菌生珲群对Al胁迫比金荞麦更敏感;Al胁迫对荞麦和金荞麦根际土壤过氧化氢酶活性均表现出较弱的抑制效应,但荞麦根际土壤始终维持较金荞麦更高的过氧化氢酶活性,这与荞麦具有更强的耐铝性有一定的关系,荞麦和金荞麦根际土壤转化酶对Al非常敏感,随着铝的加入,其活性显著下降,荞麦和金荞麦根际土壤脲酶活性的变化趋势基本一致,但整体上荞麦根际土壤脲酶活性均明显低于金荞麦,这是否与其耐铝毒特性的差异有关有待于进一步探讨.     

Toward an ecological classification of soil bacteria

Although researchers have begun cataloging the incredible diversity of bacteria found in soil, we are largely unable to interpret this information in an ecological context, including which groups of bacteria are most abundant in different soils and why. With this study, we examined how the abundances of major soil bacterial phyla correspond to the biotic and abiotic characteristics of the soil environment to determine if they can be divided into ecologically meaningful categories. To do this, we collected 71 unique soil samples from a wide range of ecosystems across North America and looked for relationships between soil properties and the relative abundances of six dominant bacterial phyla (Acidobacteria, Bacteroidetes, Firmicutes, Actinobacteria, alpha-Proteobacteria, and the beta-Proteobacteria). Of the soil properties measured, net carbon (C) mineralization rate (an index of C availability) was the best predictor of phylum-level abundances. There was a negative correlation between Acidobacteria abundance and C mineralization rates (r2 = 0.26, P < 0.001), while the abundances of beta-Proteobacteria and Bacteroidetes were positively correlated with C mineralization rates (r2 = 0.35, P < 0.001 and r2 = 0.34, P < 0.001, respectively). These patterns were explored further using both experimental and meta-analytical approaches. We amended soil cores from a specific site with varying levels of sucrose over a 12-month period to maintain a gradient of elevated C availabilities. This experiment confirmed our survey results: there was a negative relationship between C amendment level and the abundance of Acidobacteria (r2 = 0.42, P < 0.01) and a positive relationship for both Bacteroidetes and beta-Proteobacteria (r2 = 0.38 and 0.70, respectively; P < 0.01 for each). Further support for a relationship between the relative abundances of these bacterial phyla and C availability was garnered from an analysis of published bacterial clone libraries from bulk and rhizosphere soils. Together our survey, experimental, and meta-analytical results suggest that certain bacterial phyla can be differentiated into copiotrophic and oligotrophic categories that correspond to the r- and K-selected categories used to describe the ecological attributes of plants and animals. By applying the copiotroph-oligotroph concept to soil microorganisms we can make specific predictions about the ecological attributes of various bacterial taxa and better understand the structure and function of soil bacterial communities.     

亚热带赤红壤不同林型对土壤微生物区系的影响

研究不同人工林型下上壤微生物区系的差异与变化．定期采样测定结果表明，不同林型下的土壤微生物总数顺序为混交林＞豆科纯林＞纯桉林；其数量在一年中随季节变化很大，各种林型均以秋季最大．其次是春、冬季，夏季最小；三大类随中又以细菌所占比例最大，其次为放线菌、真菌；它们各自的优势种群在组成上各林地间差别不大，而且全年都保持较稳定的比例．无论是微生物种类还是其数量，都以混交林多于纯林，而在纯林中又以豆科纯林多于桉林．     

Growth of Brassica juncea under chromium stress: influence of siderophores and indole 3 acetic acid producing rhizosphere bacteria

Plant growth promoting rhizobacterial (PGPR) strains A3 and S32 have been shown to promote the growth of Brassica juncea under chromium stress which has been related to the microbial production of siderophores and indole 3 acetic acid (IAA). The aim of the present study is to evaluate the importance of siderophores and IAA producing PGPR on the growth of Brassica juncea under chromium stress. The production of IAA and siderophores were observed in the strains A3 and S32, respectively. Both PGPR strains promote the growth of Brassica juncea under chromium stress. The maximum growth was observed in plants inoculated with siderophores producing strain 32. Both the bacterial inoculum did not influence the uptake of chromium by plants. The present observation showed that PGPR isolates A3 and S32 are capable of protecting the plants against the inhibitory effects of chromium by producing the siderophores and IAA.     

铜陵新桥矿区土壤中耐Cu微生物的筛选研究

选择安徽铜陵新桥矿区富Cu的污染土壤,充分利用微生物受自然环境重金属胁迫而产生耐性这一特点,进行土壤中耐Cu微生物的筛选研究。实验过程中分别配制三种不同的培养基,细菌、真菌和放线菌培养基。在水浴恒温振荡器中对土壤中耐受重金属的微生物进行驯化,将得到的对Cu2+耐受性最高的液体培养基作为菌源,在琼脂平板培养基上进行划线分离,并将得到的纯菌株在光学显微镜下进行形态观察,菌种经试管斜面富集培养后保存在4℃冰箱中以便后续使用。研究发现,土样中细菌和真菌对Cu的耐受性低,最高耐受质量浓度分别只达到500mg·L-1和1100mg·L-1。而放线菌表现出Cu高耐受性,分离得到的放线菌耐受Cu的质量浓度最高达到10000mg·L-1,初步鉴定该放线菌株为链霉菌属。该放线菌菌种可能同时对Cu有吸附降解特性,具有成为污染土壤生物治理的高效耐受吸附菌种的潜力巨大。