Polyphosphate-Accumulating and Denitrifying Bacteria Isolated from Anaerobic-Anoxic and Anaerobic-Aerobic Sequencing Batch Reactors

In this study, phosphate-accumulating bacteria achieved complete phosphate removal in two different systems: an anaerobic-anoxic sequencing batch reactor and an anaerobic-aerobic sequencing batch reactor. This result shows that phosphate-accumulating bacteria in the A₂ SBR can use nitrate as terminal electron acceptor instead of oxygen. Phosphate-accumulating bacteria accumulated phosphate with a rates between 30 and 70 mg P/L/h in the A/O SBR and between 15 and 32 mg P/L/h in the A₂ SBR. Twenty denitrifying isolates were screened from A₂ SBR and nine from A/O SBR. Identification of these isolates by the Biolog system and the API 20 NE identification kit revealed that the most active denitrifiers in both SBRs reactors were species of Ochrobactrum, Pseudomonas, Corynebacterium, Agrobacterium, Aquaspirillum, Haemophilus, Xanthomonas, Aeromonas, and Shewanella. The most active phosphate accumulating and denitrifying bacteria were identified as Agrobacterium tumefaciens B, Aquaspirillum dispar, and Agrobacterium radiobacter. This study showed that the active phosphate accumulating-bacteria were also the most efficient denitrifying bacteria in both reactors. Received: 24 February 1998 / Accepted: 21 July 1998     

Effects of Cycle Time on Properties of Aerobic Granules in Sequencing Batch Airlift Reactors

Summary The granulation and properties of aerobic sludge were studied in two sequencing batch airlift reactors (SBARs). The synthetic wastewater in the two reactors had initially different levels of COD (400 mg l⁻¹ in R1 and 1600 mg l⁻¹ in R2). A hydraulic cycle time of 3 and 12 h was conducted in the reactors R1 and R2, respectively and the process of granulation was observed by optical microscopy. It was found that the course of granulation at a cycle time of 3 h in R1 was shorter than that at cycle time of 12 h in R2 and the properties of aerobic granules were distinct in the reactors due to the different hydraulic cycle time. Under a cycle time of 3 h, granule diameter was around 1.0–2.0 mm, VSS ratio was 92.08% with stronger granule strength; under a cycle time of 12 h, granule diameter was around 0.5–1.0 mm, VSS ratio was 83.92% with weaker granule strength. In addition, the morphology of microorganisms in granules was obviously dissimilar when the hydraulic cycle time was different. It was concluded that the hydraulic cycle time plays a crucial role in the granulation and properties of aerobic granules. It is expected that the experimental findings will provide useful information on factors affecting aerobic granulation.     

Kinetic Studies of Reactive Azo Dye Decolorization in Anaerobic/aerobic Sequencing Batch Reactors

The decolorization kinetics of Remazol Brilliant Violet 5R (RBV-5R) and Remazol Black B (RB-B) (mono- and diazo reactive dyes, respectively) was investigated in the first 9 h (anaerobic phase) of a 24-h cycle anaerobic/aerobic sequencing batch reactor (SBR). Two distinct, successive decolorization periods were observed for both dyes, apparently due to different decolorization mechanisms. The apparent first-order rate constants were much lower for the second periods. First-order kinetics were apparently followed for both periods of RBV-5R but not for the first decolorization period of RB-B, possibly due to the occurrence of mass transfer limitations.     

荒漠土壤藻群落结构的原生演替

微生物结皮是荒漠化治理中新的热点之一,但其关键形成生物--微型藻类如何通过群落结构的变化向地衣结皮、藓类结皮转变的机理仍是未知的.本文以时空替代法,将沙坡头流沙,4、8、17、34及42龄结皮当作同一群落演替进程中的6个阶段,通过系统聚类、丰分量分析的方法首次对这一问题进行了研究,结果显示该地荒漠藻群落的原生演替朝着蓝藻总丰度和爪哇伪枝藻(Scytonema javanicum)丰度逐渐下降,纤细席藻(Phormidiumtenue)、绿藻、硅藻丰度逐渐增加的方向进行;多样性随群落演替的发展而增高;生物量在初期呈正向演替,后期随地衣、藓类的入侵逐渐下降;演替速度非常缓慢,高龄结皮中的优势种仍是建群种,只是优势度略有下降;水分、植被覆盖、地形、时间,土壤理化性质都影响演替途径和速度,特别是Mn含量对演替有重要的阈值作用.     

荒漠土壤藻群落结构的原生演替

微生物结皮是荒漠化治理中新的热点之一,但其关键形成生物——微型藻类如何通过群落结构的变化向地衣结皮、藓类结皮转变的机理仍是未知的。本文以时空替代法,将沙坡头流沙,4、8、17、34及42龄结皮当作同一群落演替进程中的6个阶段,通过系统聚类、主分量分析的方法首次对这一问题进行了研究,结果显示该地荒漠藻群落的原牛演替朝着蓝藻总丰度和爪畦伪枝藻(Scytonema javanicum)丰度逐渐下降,纤细席藻(Phormidium tenue)、绿藻、硅藻丰度逐渐增加的方向进行;多样性随群落演替的发展而增高;生物量在初期呈正向演替,后期随地衣、藓类的入侵逐渐下降;演替速度非常缓慢,高龄结皮中的优势种仍是建群种,只是优势度略有下降;水分、植被覆盖、地形、时间,土壤理化性质都影响演替徐径和速度．特别是Mn含量对演替有重要的阈值作用。     

Change in Phylogenetic Community Structure during Succession of Traditionally Managed Tropical Rainforest in Southwest China

Tropical rainforests in Southeast Asia are facing increasing and ever more intense human disturbance that often negatively affects biodiversity. The aim of this study was to determine how tree species phylogenetic diversity is affected by traditional forest management types and to understand the change in community phylogenetic structure during succession. Four types of forests with different management histories were selected for this purpose: old growth forests, understorey planted old growth forests, old secondary forests (∼200-years after slash and burn), and young secondary forests (15–50-years after slash and burn). We found that tree phylogenetic community structure changed from clustering to over-dispersion from early to late successional forests and finally became random in old-growth forest. We also found that the phylogenetic structure of the tree overstorey and understorey responded differentially to change in environmental conditions during succession. In addition, we show that slash and burn agriculture (swidden cultivation) can increase landscape level plant community evolutionary information content.     

Characterization of the Microbial Community in a Partial Nitrifying Sequencing Batch Biofilm Reactor

A lab-scale partial nitrifying sequencing batch biofilm reactor was a successful start-up. Denaturing gradient gel electrophoresis (DGGE) was used to investigate the bacterial community dynamics in three periods together with inocula sludge at ambient temperature. The DGGE profiles of bacteria and Shannon–Wiener index (H′) results showed that high free ammonia (FA) concentration referred to lower diversity in the bioreactor system. Cluster analysis indicated that microorganism in period III was similar with inocula sludge and was different from that in periods I and II. Similar results also appeared in ammonia-oxidizing bacteria (AOB) community structure and nitrite-oxidizing bacteria (NOB) community structure, and at least four AOB species and two NOB species were present in period III, respectively. Phylogenetic analysis of amoA gene sequences showed that Nitrosomonas eutropha cluster was predominant in all the three periods. With lower ammonium loads, three new operational taxonomic units formed and consisted Nitrosomonas sp. Cluster. This article demonstrated that microbial community, AOB, and NOB diversity were related with FA concentration closely at ambient temperature.     

鼎湖山针阔混交林演替过程中群落组成和结构短期动态研究

分析了鼎湖山针阔混交林永久样地在4a演变过程中群落的物种组成结构、空间结构、物种多样性以及生物量的动态变化。结果表明：群落乔、灌、草3层的物种个体数量有很大变化,但其物种组成结构变幅很小;针叶树种马尾松(Pinus massoniana)的优势地位逐步丧失,而阔叶树种荷木(Schima superba)和锥栗(Castanopsis chinensis)等优势地位日益巩固,同时中生性树种的罗伞(Ardisia quinquegona)和九节(Psychotria rubra)等地位也在加强,整个群落向常绿阔叶林演变：群落乔木层的生物量增加而灌木层的生物量逐步减少,但群落总生物量仍在增加：群落各层次物种多样性的变化及其相互关系较为复杂,但各层次的物种多样性指数只表现微小的起伏,说明针阔混交林群落的演替是一种缓慢的、较为稳定的过程。同时,在群落的演替过程中,偶见种及珍稀植物的保护值得关注。     

植物群落的演替与稳定性

演替是生物界最常见的自然现象之一。早在 2 0世纪2 0年代 ,Ｃｌｅｍｅｎｔｓ就开始了系统的演替研究 ,他提出的演替经典模式对生态学的影响一直延续至今。数十年来 ,尽管生态学家相继提出了各种各样的演替理论或假说[1,15,16,2 4 ,2 5] ,但由于地域的限制和生态学家有限的经验 ,迄今为止还没有一个统一的演替理论或模式 ,甚至连演替一词的涵义各说不一[16] 。近年来 ,邬建国等[16] 学者对百年来各种演替理论和假说作了较全面的总结和评述 ,他把尺度 等级系统理论视为现代生态学范式 ,并认为是演替研究现在和将来的发展方向。遗憾的是 ,有关…     

Bacterial Diversity and Function of Aerobic Granules Engineered in a Sequencing Batch Reactor for Phenol Degradation

Aerobic granules are self-immobilized aggregates of microorganisms and represent a relatively new form of cell immobilization developed for biological wastewater treatment. In this study, both culture-based and culture-independent techniques were used to investigate the bacterial diversity and function in aerobic phenol- degrading granules cultivated in a sequencing batch reactor. Denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA genes demonstrated a major shift in the microbial community as the seed sludge developed into granules. Culture isolation and DGGE assays confirmed the dominance of β-Proteobacteria and high-G+C gram-positive bacteria in the phenol-degrading aerobic granules. Of the 10 phenol-degrading bacterial strains isolated from the granules, strains PG-01, PG-02, and PG-08 possessed 16S rRNA gene sequences that matched the partial sequences of dominant bands in the DGGE fingerprint belonging to the aerobic granules. The numerical dominance of strain PG-01 was confirmed by isolation, DGGE, and in situ hybridization with a strain-specific probe, and key physiological traits possessed by PG-01 that allowed it to outcompete and dominate other microorganisms within the granules were then identified. This strain could be regarded as a functionally dominant strain and may have contributed significantly to phenol degradation in the granules. On the other hand, strain PG-08 had low specific growth rate and low phenol degradation ability but showed a high propensity to autoaggregate. By analyzing the roles played by these two isolates within the aerobic granules, a functional model of the microbial community within the aerobic granules was proposed. This model has important implications for rationalizing the engineering of ecological systems.     

Community Analysis of Ammonia and Nitrite Oxidizers during Start-Up of Nitritation Reactors

Partial nitrification of ammonium to nitrite under oxic conditions (nitritation) is a critical process for the effective use of alternative nitrogen removal technologies from wastewater. Here we investigated the conditions which promote establishment of a suitable microbial community for performing nitritation when starting from regular sewage sludge. Reactors were operated in duplicate under different conditions (pH, temperature, and dilution rate) and were fed with 50 mM ammonium either as synthetic medium or as sludge digester supernatant. In all cases, stable nitritation could be achieved within 10 to 20 days after inoculation. Quantitative in situ hybridization analysis with group-specific fluorescent rRNA-targeted oligonucleotides (FISH) in the different reactors showed that nitrite-oxidizing bacteria of the genus Nitrospira were only active directly after inoculation with sewage sludge (up to 4 days and detectable up to 10 days). As demonstrated by quantitative FISH and restriction fragment length polymorphism (RFLP) analyses of the amoA gene (encoding the active-site subunit of the ammonium monooxygenase), the community of ammonia-oxidizing bacteria changed within the first 15 to 20 days from a more diverse set of populations consisting of members of the Nitrosomonas communis and Nitrosomonas oligotropha sublineages and the Nitrosomonas europaea-Nitrosomonas eutropha subgroup in the inoculated sludge to a smaller subset in the reactors. Reactors operated at 30°C and pH 7.5 contained reproducibly homogeneous communities dominated by one amoA RFLP type from the N. europaea-N. eutropha group. Duplicate reactors at pH 7.0 developed into diverse communities and showed transient population changes even within the ammonia oxidizer community. Reactors at pH 7.5 and 25°C formed communities that were indistinguishable by the applied FISH probes but differing in amoA RFLP types. Communities in reactors fed with sludge digester supernatant exhibited a higher diversity and were constantly reinoculated with ammonium oxidizers from the supernatant. Therefore, such systems could be maintained at a higher dilution rate (0.75 day⁻¹ compared to 0.2 day⁻¹ for the synthetic wastewater reactors). Despite similar reactor performance with respect to chemical parameters, the underlying community structures were different, which may have an influence on stability during perturbations.     

Respiratory Succession and Community Succession of Bacterioplankton in Seasonally Anoxic Estuarine Waters

Anoxia occurs in bottom waters of stratified estuaries when respiratory consumption of oxygen, primarily by bacteria, outpaces atmospheric and photosynthetic reoxygenation. Once water becomes anoxic, bacterioplankton must change their metabolism to some form of anaerobic respiration. Analysis of redox chemistry in water samples spanning the oxycline of Chesapeake Bay during the summer of 2004 suggested that there was a succession of respiratory metabolism following the loss of oxygen. Bacterial community doubling time, calculated from bacterial abundance (direct counts) and production (anaerobic leucine incorporation), ranged from 0.36 to 0.75 day and was always much shorter than estimates of the time that the bottom water was anoxic (18 to 44 days), indicating that there was adequate time for bacterial community composition to shift in response to changing redox conditions. However, community composition (as determined by PCR-denaturing gradient gel electrophoresis analysis of 16S rRNA genes) in anoxic waters was very similar to that in surface waters in June when nitrate respiration was apparent in the water column and only partially shifted away from the composition of the surface community after nitrate was depleted. Anoxic water communities did not change dramatically until August, when sulfate respiration appeared to dominate. Surface water populations that remained dominant in anoxic waters were Synechococcus sp., Gammaproteobacteria in the SAR86 clade, and Alphaproteobacteria relatives of Pelagibacter ubique, including a putative estuarine-specific Pelagibacter cluster. Populations that developed in anoxic water were most similar (<92% similarity) to uncultivated Firmicutes, uncultivated Bacteroidetes, Gammaproteobacteria in the genus Thioalcalovibrio, and the uncultivated SAR406 cluster. These results indicate that typical estuarine bacterioplankton switch to anaerobic metabolism under anoxic conditions but are ultimately replaced by different organisms under sulfidic conditions.     

深圳市径心水库区苏铁蕨群落结构特征及演替分析

苏铁蕨(Brainea insignis)最早出现于古生代泥盆纪,是重要孑遗种和珍稀濒危植物,对研究古植物区系及蕨类植物的起源和演化具有重要意义。该研究采用相邻格子法对深圳市径心水库区的苏铁蕨群落进行群落学研究,分析径心水库区苏铁蕨群落结构和演替特点,为苏铁蕨的保护提供理论和实践依据。结果表明:(1)深圳径心水库区的苏铁蕨群落属于南亚热带常绿阔叶林,在1 600m2的样地中共有维管束植物72种,隶属于45科66属,其中种类组成以热带成分占绝对优势,占非世界属的88.33%。(2)该苏铁蕨群落垂直结构明显,可划分为乔木2亚层、灌木层和草本层,层间植物较丰富;各种群的重要值分析表明,鸭脚木(Schefflera octophylla)、苏铁蕨(Brainea insignis)、九节(Psychotria rubra)、鼠刺(Itea chinensis)、银柴(Aporusa dioica)是该群落的主要优势种,其重要值分别为:53%、38%、28%、23%和22%。(3)年龄结构分析表明,主要优势种群如银柴、鼠刺和豺皮樟(Litsea rotundifolia)等均属于增长型种群,而苏铁蕨种群却呈现出一定的衰退趋势,说明该群落正处在旺盛发展阶段并且会不断演化替换掉苏铁蕨种群。(4)该研究区群落种群的频度规律为A级B级C级D级E级,与Raunkiaer的L形频度定律曲线相一致;与其他邻近地区进行比较,深圳径心水库区的苏铁蕨群落显示出较低的物种丰富度,可能是受海风和人类活动的影响比较大,应对该苏铁蕨群落进行适当的干预和保育,清理上层枯枝枯藤,加强林内透视度,增加光照。     

四明湖水库浮游动物群落演替

于2012年8月至2013年7月对四明湖水库水体理化特性以及浮游动物的种类、数量和生物量进行逐月采样调查,分析了水库的浮游动物群落特征及其影响因子。调查期间共检测到浮游动物150种,丰度198.0~7 258.0 ind/L,年平均3 795.2 ind/L,生物量0.28~5.64 mg/L,年均值为1.11 mg/L,浮游动物丰度和生物量空间差异不显著,但季节变化明显。对应分析(CA)和后续拟合表明,水温、叶绿素a、总磷、真光层深度、氨氮以及水位是驱动浮游动物结构变化的主要环境因子,各点的影响因子间存在空间差异性。对比24年前历史资料,发现四明湖水库浮游动物数量和生物量均减少,浮游动物出现小型化,推测认为是鱼类捕食的下行效应、蓝藻密度增加及蓝藻产生藻毒素增加影响浮游动物繁殖力所致。水质评价结果表明,四明湖水库目前处于中营养水平,但有向富营养型发展的趋势。     

Bacterial Succession in Glacial Forefield Soils Characterized by Community Structure,Activity and Opportunistic Growth Dynamics

The succession of bacterial communities inhabiting the forefield of the Dammaglacier (Switzerland) was investigated in soils ranging in successional age from 0 to 100 years since deglaciation. Overall activity per bacterial cell was estimated by the amount of fluorescein diacetate (FDA) hydrolyzed per DAPI-stained cell, and an index of "opportunism" was determined from the ratio of culturable to total cells (C:T ratio). Ribosomal intergenic spacer analysis (RISA) was used to estimate the richness of dominant phylotypes and to construct rank-abundance plots of the dominant populations. We observed a biphasic trend in specific cellular activity, which exhibited minima in the 0- and 100-year-old soils while a maximum activity per cell was reached in the 70-y soil. On average, the C:T ratio showed the same trend as the specific activity, although we observed some differences between the two sampling transects. RISA revealed a decrease in dominant phylotype richness as successional age increased, and rank-abundance plots indicated that the evenness of the dominant bacterial phylotypes significantly decreased with successional age. The combination of specific cellular activity and C:T ratio results suggested the presence of an r-K continuum of bacteria while RISA showed that richness and evenness of dominant phylotypes decreased with successional age. We conclude that bacterial succession in the glacier forefield was a dynamic process with adaptation to the differing stages of succession occurring on both the individual and community levels.     

红松林不同演替阶段夏季鸟类群落研究

红松林不同演替阶段夏季鸟类群落研究常家传鲁长虎刘伯文许青（东北林业大学,哈尔滨１５００４０）ＳｔｕｄｙｏｆｔｈｅＢｉｒｄｓＣｏｍｍｕｎｉｔｙＳｔｒｕｃｔｕｒｅｉｎＤｉｆｅｒｅｎｔＳｕｃｃｅｓｉｏｎＰｅｒｉｏｄｏｆＫｏｒｅａｎＰｉｎｅＦｏｒｅｓｔ．Ｃｈ...     

Enrichment of Denitrifying Methane-Oxidizing Microorganisms Using Up-Flow Continuous Reactors and Batch Cultures

Denitrifying anaerobic methane oxidizing (DAMO) microorganisms were enriched from paddy field soils using continuous-flow and batch cultures fed with nitrate or nitrite as a sole electron acceptor. After several months of cultivation, the continuous-flow cultures using nitrite showed remarkable simultaneous methane oxidation and nitrite reduction and DAMO bacteria belonging to phylum NC10 were enriched. A maximum volumetric nitrite consumption rate of 70.4±3.4 mg-N·L⁻¹·day⁻¹ was achieved with very short hydraulic retention time of 2.1 hour. In the culture, about 68% of total microbial cells were bacteria and no archaeal cells were detected by fluorescence in situ hybridization. In the nitrate-fed continuous-flow cultures, 58% of total microbial cells were bacteria while archaeal cells accounted for 7% of total cell numbers. Phylogenetic analysis of pmoA gene sequence showed that enriched DAMO bacteria in the continuous-flow cultivation had over 98% sequence similarity to DAMO bacteria in the inoculum. In contrast, for batch culture, the enriched pmoA gene sequences had 89–91% sequence similarity to DAMO bacteria in the inoculum. These results indicate that electron acceptor and cultivation method strongly affect the microbial community structures of DAMO consortia.     

Bacterial Community Structure in Patagonian Andean Lakes Above and Below Timberline: From Community Composition to Community Function

Lakes located above the timberline are remote systems with a number of extreme environmental conditions, becoming physically harsh ecosystems, and sensors of global change. We analyze bacterial community composition and community-level physiological profiles in mountain lakes located in an altitude gradient in North Patagonian Andes below and above the timberline, together with dissolved organic carbon (DOC) characterization and consumption. Our results indicated a decrease in 71 % of DOC and 65 % in total dissolved phosphorus (TDP) concentration as well as in bacteria abundances along the altitude range (1,380 to 1,950 m a.s.l.). Dissolved organic matter (DOM) fluorescence analysis revealed a low global variability composed by two humic-like components (allochthonous substances) and a single protein-like component (autochthonous substances). Lakes below the timberline showed the presence of all the three components, while lakes above the timberline the protein-like compound constituted the main DOC component. Furthermore, bacterial community composition similarity and ordination analysis showed that altitude and resource concentration (DOC and TDP) were the main variables determining the ordination of groups. Community-level physiological profiles showed a mismatch with bacteria community composition (BCC), indicating the absence of a relationship between genetic and functional diversity in the altitude gradient. However, carbon utilization efficiencies varied according to the presence of different compounds in DOM bulk. The obtained results suggest that the different bacterial communities in these mountain lakes seem to have similar metabolic pathways in order to be able to exploit the available DOC molecules.