浙江天台山不同林型土壤环境的微生物区系和细菌生理群的多样性

研究了天台山8种土壤环境的微生物区系,细菌生理群分布、组成和多样性。结果表明：黄山松林、竹林和云锦杜鹃林土壤中细菌、真菌和放线菌数量较多,而柳杉林土壤中较少。微生物数量与土壤有机质、全氮、全磷含量以及土壤凋落物的关系较大。每种土壤环境的细菌、真菌和放线菌占微生物总量的比例为：细菌数量最多,放线菌居中,真菌较少。土壤细菌生理群在天台山8种土壤环境中的分布有较大的差异。好气纤维素分解菌、好气固氮菌、氨化细菌、有机磷分解菌、无机磷分解菌在8种土壤环境中均占有较大的比例,是每种土壤环境的优势菌群,而反硝化细菌和反硫化细菌在每种土壤环境中占有的数量比例均相对较小,处于次要地位。七子花林、竹林、云锦杜鹃林和日本花柏林土壤细菌生理群的Simpson指数和Shannon-Wiener指数均较小,柳杉林、茶园、金钱松林、黄山松林土壤细菌生理群的Simpson指数和Shannon-Wiener指数相对较大。     

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。     

南疆连作棉田几种有益细菌的动态变化规律

通过稀释涂布平板法研究农一师二团和三团不同连作年限棉田土壤中好气性自生固氮菌、钾细菌、纤维素分解细菌、无机磷细菌、有机磷细菌等有益土壤细菌的总数分布, 以探讨棉花连作对土壤微生物的影响及土壤微生物对棉花生长的影响。结果表明, 5种细菌菌数均在花铃期达到最高, 苗期最低, 受耕作制度影响, 播前期菌数较高。5种细菌菌数随棉花连作年限的增加没有表现出有规律的变化, 受棉花连作影响较小。好气性自生固氮菌菌数在二团各生育期均比三团高, 其他4种细菌在不同生育期变化各不相同。土壤有益细菌与土壤多种离子养分呈负相关, 自生固氮菌与土壤全氮呈显著正相关。     

大棚蔬菜轮/连作系统土壤肥力与微生物因子综合评价

从土壤肥力与微生物因子探索连茬障碍机理,以期为其提供科学依据。研究草莓番茄轮作(RST)、番茄连作4年(CT4)和番茄连作10年(CT10)3种蔬菜种植模式根际与非根际土壤微生物区系及生理菌群,并对土壤肥力与微生物生物因子进行主成分分析。结果表明根际土壤微生物三大类群和生理菌群数量均高于非根际,根际效应显著。番茄连作根际与非根际土壤细菌和放线菌数量呈现先增加后减少趋势;真菌数量呈线型增加趋势,CT4和CT10在根际与非根际较RST分别增加9.09%和2.11%、75.48%和57.72%。番茄连作根际土壤硝化细菌和好气性自生固氮菌数量的减少,氨化细菌与好气性纤维素分解菌在短期连作表现为增加长期减少的变化趋势;解钾菌、无机磷和有机磷细菌数量在根际与非根际土壤均减少。在6种研究的种植模式中,RST根际土壤状况最好,其次为CT4的根际与RST非根际土壤,CT10的根际土壤、CT4与CT10非根际土壤状况最差。结论是蔬菜连作造成土壤质量下降,连作年限越长下降越显著。     

天祝高寒草地植被、土壤及土壤微生物时间动态的比较

对天祝高寒草地21a前（1982年）、后（2003年）植被状况、土壤理化性质、土壤三大类微生物（细菌、放线菌和真菌）和各生理群微生物（硝化细菌、好气性固氮菌和好气性纤维素分解菌）及不同退化程度（围栏内、围栏外和鼠丘地）草地土壤微生物数量变化特点进行了对比研究。结果表明：（1）与1982年相比,目前该区天然草地植被总盖度、主要优良牧草种类、产草量等显著下降,草地植被退化明显;（2）草地土壤pH升高,土壤含水量、有机质、氮、磷含量均下降,草地土壤理化性质劣于1982年;（3）目前该区天然草地土壤三大类微生物数量及各生理群微生物数量变化十分明显,1982年土壤细菌、放线菌和真菌及微生物总数分别是2003年的153．6、5．5、4．1倍和151．2倍;土壤硝化细菌、好气性固氮菌和好气性纤维素分解菌数量分别是2003年的5．7、43．3倍和94．4倍;（4）轻度退化草地（围栏内）土壤各类微生物数量明显高于严重退化草地（围栏外、鼠丘地）,其数量前者一般为后者的1．5—4．5倍。     

花椒（Zanthoxylum bungeanum）凋落物分解过程中酚酸的释放及其浸提液对土壤化学性质的影响

应用分解网袋法研究了花椒凋落物分解过程中（0、10、30d和60d）酚酸的释放动态及凋落物浸提液对花椒林地土壤化学性质的影响。结果表明：花椒凋落物在分解过程中呈现出明显的毒性动态。凋落物分解的60d中，凋落物残留量在前30d内变化最大，30d后无显著变化；凋落物中酚酸含量随分解时间的延长，呈显著降低的趋势，且在分解10d时，酚酸释放量最大。4个分解动念的凋落物浸提液显著地改变了土壤好气性自生固氮菌、氨化细菌、好气性纤维素分解菌的数量和土壤pH值、酚酸含量、铵态氮、有效磷等化学性质。不同分解时间的凋落物浸提液均造成了土壤pH值的显著升高；分解10d的凋落物浸提液对土壤铵态氮的含量具有显著的降低作用，对土壤好气性自生固氮菌和氨化细菌的生长均具有显著的促进作用，而对好气性纤维素分解菌的生长具有抑制作用；分解60d的凋落物浸提液显著地降低了土壤酚酸含量，对土壤有效磷含量具有显著的升高作用，对好气性自生固氮菌的生长具有抑制作用，而对好气性纤维素分解菌的生长具有促进作用。     

四川盆地亚热带常绿阔叶林不同物候期凋落物分解与土壤动物群落结构的关系

为了解植物生长不同物候时期凋落物分解过程中土壤动物群落结构动态及其与凋落物分解的关系,以四川盆地亚热带常绿阔叶林典型人工林树种马尾松和柳杉,次生林树种香樟和麻栎凋落物为研究对象,采用凋落物分解袋试验研究,凋落物分解过程中土壤动物的群落特征。4种凋落物分解袋共获得土壤动物8047只,其中,柳杉(2341只)>香樟(2105只)>马尾松(2046只)>麻栎(1555只)。其中,秋末落叶期、萌动期和展叶期,马尾松凋落物袋中主要以捕食性土壤动物为优势类群,而后以菌食性土壤动物为主;香樟凋落物袋中除秋末落叶期和叶衰期以菌食性土壤动物为主要优势类群外,其他各时期均以捕食性土壤动物为主要优势类群;柳杉凋落物分解各时期均以菌食性土壤动物为主要优势类群;麻栎凋落物分解在前3个时期以菌食性为主,而后以植食性土壤动物为主要优势类群。相关分析表明,在秋末落叶期和萌动期土壤动物的个体密度主要和氮、磷含量及其格局密切相关,叶衰期主要和难分解组分木质素显著相关。除在秋末落叶期土壤动物对凋落物分解的贡献率与土壤动物的个体密度显著相关外,其余主要物候关键时期均与土壤动物的类群密度及其食性显著相关。     

黄土丘陵区不同植被土壤氮素转化微生物生理群特征及差异

采用最大或然计数法(most probable number, MPN)对黄土高原洞子沟流域不同植被恢复阶段土壤氮素微生物生理群(氨化细菌、亚硝化细菌、反硝化细菌)数量分布特征进行了测定,结果表明:1)土壤氨化细菌、亚硝化细菌和反硝化细菌数量随植被恢复而增加,三者最大值分别为最小值的74、4和31倍,其中氨化细菌和反硝化细菌的数量在铁杆蒿群落最低,辽东栎群落最高,亚硝化细菌数量在丁香群落最低,辽东栎群落最高;2)植被恢复对各氮素生理群影响不同,对氨化细菌影响最大,其次分别为反硝化细菌和亚硝化细菌;3)各氮素生理群数量差异较大,氨化细菌>反硝化细菌>亚硝化细菌。研究区氨化细菌占总数的75%-80%,反硝化细菌占20%-25%时,生态系统最为稳定;4)土壤理化性质与各功能菌关系紧密,其中,土壤容重和硝态氮含量与微生物数量相关性最大,全钾、矿化氮和微生物量氮也表现出很大的相关性。     

地黄连作对根际微生物区系及土壤酶活性的影响

以地黄连作2年和1年的土壤为研究对象,分别测定了根际微生物区系变化及根际土壤酶活性．结果表明：地黄连作对其根际微生物区系及土壤酶活性产生了较大的影响．随种植年限的增加,根际细菌和真菌减少,但差异均不显著;放线菌增多,连作2年的土壤约为1年的4倍．土壤中氨化细菌、好气性固氮菌、硫化细菌、反硝化细菌和嫌气性纤维素分解菌分别增加了25．99、45．39、11．43、1．36和1．43倍,而好气性纤维素分解菌减少了86．74％．连作地黄根系的分泌物对脲酶、多酚氧化酶、蔗糖酶、蛋白酶和纤维素酶活性具有促进作用,分别增加了62．87％、9．43％、47．91％、139．62％和31．33％,而对过氧化氢酶则呈抑制作用．说明地黄连作会破坏根际微生物种群平衡．     

东祁连山退化高寒草地土壤细菌群落与土壤环境因子间的相互关系

为探究东祁连山不同退化高寒草地细菌群落分布特征与土壤环境因子间的相互关系,采用高通量测序技术对轻度、中度和重度退化草地的土壤细菌群落结构变化及其多样性进行分析,运用CANOCO 4.5软件对土壤细菌群落与土壤环境因子间关系进行冗余分析(RDA).结果表明:不同退化高寒草地土壤理化性质间均差异显著,高通量测序共得到257125条有效序列,180826条优质序列,4790个OTUs.细菌群落Chao1指数依次为轻度>中度>重度;Shannon指数依次为轻度>重度>中度.系统发育分析表明,各样地土壤细菌类群分属于33个门,其中放线菌门、变形菌门和厚壁菌门是3种不同退化草地土壤中的优势类群.对不同退化草地土壤细菌各门所占比例分析发现,放线菌门、酸杆菌门和变形菌门随着退化程度加剧先减少后增加,厚壁菌门反之.RDA分析结果显示,细菌优势类群与蔗糖酶、纤维素酶和磷酸酶呈极显著相关,与pH、电导率、速效氮、速效钾呈显著相关.说明东祁连山不同退化高寒草地土壤细菌群落间差异明显,土壤环境因子是影响土壤细菌群落分布的重要因素.     

天台山不同林型土壤微生物区系及其商值(qMB,qCO2)

研究了天台山8种林型下土壤微生物数量、微生物量碳、微生物量氮、微呼吸速率和微生物商值(qMB,qCO2),结果表明,均以云锦杜鹃林、黄山松林、茶园和竹林土壤中较大,以柳杉林土壤最小。天然林土壤的上述指标的平均水平均高于人工林土壤,所产生的差异是不同林型的立地条件和土壤性状综合影响的结果qCO2值以柳杉林、日本花柏林和茶园土壤最高(4．52％,4．43％,4．26％),云锦杜鹃林、黄山松林和七子花林土壤相对较低(3．475％,3．82％,3．70％),比前者土壤质量较好,可持续利用潜力大。     

喀斯特原生土壤与退化生态系统土壤细菌群落结构

运用PCR-RFLP技术,对桂西北喀斯特原生土壤和退化生态系统土壤细菌16S rDNA基因多样性及系统发育关系进行了研究.结果表明：原生土壤比退化生态系统土壤具有更丰富的16S rDNA基因型和更高的多样性指数,两样地共有的基因型仅有2个.从每种基因型中随机选择一个克隆子作为代表进行测序分析,所有序列与GenBank 数据库中序列的同源性为87%～100%,且两样地中均有超过一半的基因型序列与数据库中已知序列同源性低于97%,属于分类在“种”地位上的新发现细菌;通过系统发育研究将两样地的细菌分为10大类群,两样地共同拥有5大类群,但两样地的细菌优势类群明显不同,原生土壤为Proteobacteria,含39种基因型,占总克隆子数的58.0%,退化生态系统土壤为Acidobacteria和Proteobacteria,分别含19种和15种基因型,占总克隆子数的32.5%和30.5%;与原生土壤细菌类群相比,退化生态系统土壤Proteobacteria类群明显减少,Acidobacteria类群明显增加.土壤理化性质及土壤环境因素的差异是引起两类型土壤细菌多样性差异的原因.     

Viability, diversity and composition of the bacterial community in a high Arctic permafrost soil from Spitsbergen, Northern Norway

The viable and non-viable fractions of the bacterial community in a 2347-year-old permafrost soil from Spitsbergen were subjected to a comprehensive investigation using culture-independent and culture-dependent methods. LIVE/DEAD BacLight staining revealed that 26% of the total number of bacterial cells were viable. Quantitatively, aerobic microcolonies, aerobic colony-forming units and culturable anaerobic bacteria comprised a minor fraction of the total number of viable bacteria, which underlines the necessity for alternative cultivation approaches in bacterial cryobiology. Sulfate reduction was detected at temperatures between -2 degrees C and 29 degrees C while methanogenesis was not detected. Bacterial diversity was high with 162 operational taxonomic units observed from 800 16S rDNA clone sequences. The 158 pure cultures isolated from the permafrost soil affiliated with 29 different bacterial genera, the majority of which have not previously been isolated from permafrost habitats. Most of the strains isolated were affiliated to the genera Cellulomonas and Arthrobacter and several of the pure cultures were closely related to bacteria reported from other cryohabitats. Characterization of viable bacterial communities in permafrost soils is important as it will enable identification of functionally important groups together with the as yet undescribed adaptations that bacteria have evolved for surviving subzero temperatures for millennia.     

Vertical structure of bacterial communities in peats of the Yakhroma river floodplain

The abundance and taxonomic structure of soil bacterial communities have been studied in different geomorphological parts of the Yakhroma floodplain. It has been found that the numbers of bacteria reach a peak in calcareous peat soil under forest near the floodplain terrace, decreasing to a minimum in soddy alluvial soil near the riverbed. All soils are characterized by the presence of different ecological-trophic bacterial groups capable of peat destruction. Seasonal dynamics of the structure of bacterial communities and, in some soil types, its spatial dynamics accounted for by changes in the botanical structure of peat across its profile have been revealed. All peat soils in the floodplain have high contents of organic matter and neutral pH and, therefore, are favorable biotopes for the development of saprotrophic bacteria. This, in turn, largely accounts for high productivity and stability of this agroecosystem as a whole.     

Characterizing cultivable soil microbial communities from copper fungicide-amended olive orchard and vineyard soils

Use of copper-based fungicides has led to an increase in the total Cu content in agriculture soils. The focus of this study was to determine fractionation of Cu and to investigate the structure and the diversity of cultivable bacterial communities in two vineyards (one 25 years old and one 2 years old), one olive orchard and two forest soils. All soils developed on an Oligocene sandstone. The concentration of total Cu in the old vineyard (176.6 mg kg⁻¹) and olive orchard (145.5–296.7 mg kg⁻¹) was from 5 to 10 times higher than in forest soils. The major amount of Cu was found bound to the humic substances in cultivated soils, whereas in forest soils Cu was found in the residual mineral fraction. A relationship was found between the number of cultivable Cu-tolerant bacteria and total Cu content in soil. In the cultivated soils, Cu had a toxicological effect on bacterial community, and thereby Cu-levels > to 145 mg kg⁻¹ could be a risk to soil biota. Microbial communities were analysed by community level physiological profiling (CLPP), using the Biolog system, and by the amplified ribosomal DNA restriction analysis (ARDRA) approach. Only when cell suspensions containing 10⁴ colony-forming units (c.f.u.) were inoculated in each well of Biolog EcoPlates it was possible to discriminate microbial communities from different soil samples. As expected, 16S ARDRA showed that cultivated soils had a lower microbial diversity in respect to forest soils.     

Redox fluctuation structures microbial communities in a wet tropical soil

Frequent high-amplitude redox fluctuation may be a strong selective force on the phylogenetic and physiological composition of soil bacterial communities and may promote metabolic plasticity or redox tolerance mechanisms. To determine effects of fluctuating oxygen regimens, we incubated tropical soils under four treatments: aerobic, anaerobic, 12-h oxic/anoxic fluctuation, and 4-day oxic/anoxic fluctuation. Changes in soil bacterial community structure and diversity were monitored with terminal restriction fragment length polymorphism (T-RFLP) fingerprints. These profiles were correlated with gross N cycling rates, and a Web-based phylogenetic assignment tool was used to infer putative community composition from multiple fragment patterns. T-RFLP ordinations indicated that bacterial communities from 4-day oxic/anoxic incubations were most similar to field communities, whereas those incubated under consistently aerobic or anaerobic regimens developed distinctly different molecular profiles. Terminal fragments found in field soils persisted either in 4-day fluctuation/aerobic conditions or in anaerobic/12-h treatments but rarely in both. Only 3 of 179 total fragments were ubiquitous in all soils. Soil bacterial communities inferred from in silico phylogenetic assignment appeared to be dominated by Actinobacteria (especially Micrococcus and Streptomycetes), "Bacilli," "Clostridia," and Burkholderia and lost significant diversity under consistently or frequently anoxic incubations. Community patterns correlated well with redox-sensitive processes such as nitrification, dissimilatory nitrate reduction to ammonium (DNRA), and denitrification but did not predict patterns of more general functions such as N mineralization and consumption. The results suggest that this soil's indigenous bacteria are highly adapted to fluctuating redox regimens and generally possess physiological tolerance mechanisms which allow them to withstand unfavorable redox periods.     

杉木拟赤杨混交林林分生产力及生态效应研究

 本文从林分结构、生物量、群落特征、生产力、培肥土壤、涵养水源及林内小气候等方面对不同混交模式的杉木拟赤杨混交林及其纯林进行的研究结果表明：杉木拟赤杨是具有较高生产力和协调种间关系能力的针阔混交树种。7年生3:1带状混交林蓄积量和生物量分别比杉木纯林提高7.24％和18.22％,同时混交林还表现出比杉木纯林更好的培肥土壤、涵养水源、改善林内小气候等生态功能。应用AHP法进行不同混交模式的综合选择结果表明：3:1杉木拟赤杨带状混交模式是值得南方林区大力推广的杉阔混交模式。     

Bacterial functional redundancy along a soil reclamation gradient

A strategy to measure bacterial functional redundancy was developed and tested with soils collected along a soil reclamation gradient by determining the richness and diversity of bacterial groups capable of in situ growth on selected carbon substrates. Soil cores were collected from four sites along a transect from the Jamari tin mine site in the Jamari National Forest, Rondonia, RO, Brazil: denuded mine spoil, soil from below the canopy of invading pioneer trees, revegetated soil under new growth on the forest edge, and the forest floor of an adjacent preserved forest. Bacterial population responses were analyzed by amending these soil samples with individual carbon substrates in the presence of bromodeoxyuridine (BrdU). BrdU-labeled DNA was then subjected to a 16S-23S rRNA intergenic analysis to depict the actively growing bacteria from each site. The number and diversity of bacterial groups responding to four carbon substrates (L-serine, L-threonine, sodium citrate, and alpha-lactose hydrate) increased along the reclamation-vegetation gradient such that the preserved forest soil samples contained the highest functional redundancy for each substrate. These data suggest that bacterial functional redundancy increases in relation to the regrowth of plant communities and may therefore represent an important aspect of the restoration of soil biological functionality to reclaimed mine spoils. They also suggest that bacterial functional redundancy may be a useful indicator of soil quality and ecosystem functioning.     

池塘氮循环中各种细菌与理化因子的相关性研究

对精养鱼池的水体及淤泥进行多次采样,用统计学分析处理,结果表明：硝化类细菌总体上与各主要理化因子的相关性较强（R＞0．60）,其中氨化菌主要与溶氧相关程度较高;反硝化菌主要与有效磷相关程度较高;亚硝化菌主要与氨氮负相关程度较高;硝化菌主要与亚硝酸盐相关程度较高。硝化类细菌与异养菌之间的相关性则更强,如反硝化菌与厌养菌（R＝0．944,P＝0．001）、拓硝化菌和好氧异养菌（R＝0．832,P＝0．003）皆显正相关,亚硝化菌和厌氧异养菌（R＝－0．76,P＝0．009）显负相关;而在硝化类细菌之间的相关程度却较弱（R＜0．60）,表明池塘硝化类细菌对水质具有一定的调控作用,但相互之间的依赖性不强,各自相对独立地发挥作用。