Isolde Röske

Sächsische Akademie der Wissenschaften zu Leipzig, Leipzig, Saxony, Germany

Are you Isolde Röske?

Claim your profile

Publications (32)62.97 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Durch die Änderung der klimaabhängigen, hydrophysikalischen Bedingungen wurde die „Re-Oligotrophierung“ der Talsperre (im Sinne eines Rückganges der Phytoplanktonproduktion) nach 1990 völlig verhindert. Das bedeutet keineswegs, dass Anstrengungen zur Minderung der Phosphorbelastung nicht sinnvoll wären, denn die Untersuchungen zeigen gleichzeitig, dass ohne diese Reduzierung der Phosphorlast nach 1990 die Auswirkungen der veränderten klimatischen Bedingungen auf das Phytoplankton sehr wahrscheinlich wesentlich erheblicher, d.h. noch weit höhere Biomassen die Folge gewesen wären. Die Ergebnisse belegen, dass die Entflechtung der komplexen Steuermechanismen, die Aufdeckung dieser Zusammenhänge und ihre Quantifizierung sowie die Erkenntnis über den enormen Einfluss klimatisch gesteuerter Umweltgrößen tatsächlich nur mit dieser außergewöhnlich langen, ununterbrochenen und detaillierten Dokumentation möglich gewesen sind. Mit einem Datensatz von "nur" 22 Jahren, also ohne die Jahre vor 1990, wäre die gravierende Bedeutung klimagesteuerter Einflüsse nicht sichtbar und nachvollziehbar geworden. Ein eindrucksvollerer Beweis für die Notwendigkeit ökologischer Langzeitforschung zur Aufklärung der Folgen globaler Veränderungen ist kaum möglich.
    Abhandlungen der Sächsischen Akademie der Wissenschaften zu Leipzig, Mathematisch-Naturwissenschaftliche Klasse. 10/2013; Band 65(Heft 5):35-44.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Niemand ist in der Lage, genau vorherzusagen, wie sich z.B. in Zukunft das Klima verändern wird. Wasserwirtschaftliche Planung setzt aber zumindest hinreichend determinierte Annahmen über die künftige Entwicklung maßgeblicher Einflussfaktoren voraus. Solche Annahmen (Szenarios) können nur formuliert und unter Anwendung von Modellen analysiert werden, wenn globale und regionale Trends bekannt sind. Sozioökonomische oder Klimaänderungen verlaufen in der Regel allmählich, aber nie gleichmäßig. Sie sind von saisonalen und jährlichen Schwankungen und von stochastischen Veränderungen überlagert. Die Reaktion von Ökosystemen darauf ist noch wesentlich komplizierter. Hier kann es auch bei kontinuierlicher Veränderung der Einflussgrößen zu einem plötzlichen Umschlagen von Strukturen und Funktionen in einen neuen Zustand kommen. Daher erfordert das Erkennen von Trends und struktureller Veränderungen „einen langen Atem“ bei der Erforschung ökologischer Systeme, insbesondere bei aquatischen mit hohen und praxisrelevanten Änderungsraten. Dies gilt auch für die TS-Forschung. Anhand der an der TSS gewonnenen Datensätze lässt sich zeigen, dass selbst bei 20jähriger Dauer der Untersuchungen wesentliche Veränderungen nicht hätten wahrgenommen, geschweige denn erklärt werden können. Ja nicht einmal nach nunmehr 39 Jahren Forschung an der TSS sind wir in der Lage, einen Großteil wesentlicher Fragen zu beantworten und aktuelle Entwicklungen der Wasserbeschaffenheit zweifelsfrei zu erklären. Allerdings wissen wir heute sehr viel mehr als noch vor wenigen Jahren. Und dieses Wissen hat sich bereits in vielfältiger Weise in der Praxis der TS-Bewirtschaftung nutzbringend niedergeschlagen. Und ja, ökologische Langzeitforschung ist teuer. Aber eine einzige, aufgrund falscher Annahmen realisierte Investition an nur einer TS oder in nur einem Wasserwerk kann kostspieliger sein als mehrere Jahre Forschung.
    Abhandlungen der Sächsischen Akademie der Wissenschaften zu Leipzig, Mathematisch-Naturwissenschaftliche Klasse. 10/2013; Band 65(Heft 5):21-34.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Enhanced biological phosphorous removal (EBPR) from wastewater has been successfully used for more than three decades and is considered to be an environmentally friendly wastewater-treatment process. Biologically, this process is realized by incorporation of phosphate as polyphosphate (polyP) granules in activated sludge bacteria. Important groups of bacteria responsible for P removal have been identified, but the full microbial diversity involved in this process is still unknown. This paper reports on the microbial composition of activated sludge communities in eight wastewater-treatment plants (WWTPs) with different sizes and modes of operation. The polyphosphate accumulating organisms (PAOs) within this complex biocenosis were identified by fluorescent dye staining and classified by in situ hybridization techniques. Of the bacteria in the aerobic basin, 5–13% contained polyP granules. In addition, flow cytometry was used to quantify PAOs after tetracycline staining and to separate these cells. The phylogenetic affiliation of the sorted PAOs was identified by cloning and sequencing. Both workflows showed similar outcomes. The majority of PAOs in all plants were Betaproteobacteria (22%), Actinobacteria (21%), and Alphaproteobacteria (12%), with differences in the relative abundance. In addition, Bacteroidetes (12%) were detected in the clone libraries, especially Haliscomenobacter, which should be considered further with regard to its influence on the EBPR process. The denaturing gradient gel electrophoresis analyses of sorted PAOs revealed a diverse community composition of Betaproteobacteria, Actinobacteria, and Rhodocyclales in the WWTPs. PAOs were present in EBPR and non-EBPR WWTPs, and no correlation in their abundance and phylogenetic composition to the mode of operation was revealed. This study shows that specific PAO communities existed in the various WWTPs, probably favored by the respective wastewater composition, including so far unvalued PAOs species, but their active contribution in the EBPR process remains to be investigated. Read More: http://ascelibrary.org/doi/abs/10.1061/(ASCE)EE.1943-7870.0000711
    Journal of Environmental Engineering 07/2013; 139(8):1089–1098. · 1.40 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Sediments contain a huge number and diversity of microorganisms that are important for the flux of material and are pivotal to all major biogeochemical cycles. Sediments of reservoirs are affected by a wide spectrum of allochthous and autochthonous influences providing versatile environments along the flow of water within the reservoir. Here we report on the microbial diversity in sediments of the mesotrophic drinking water reservoir Saidenbach, Germany, featuring a pronounced longitudinal gradient in sediment composition in the reservoir system. Three sampling sites were selected along the gradient, and the microbial communities in two sediment depths were characterized using catalysed reporter deposition fluorescence in situ hybridization (CARD-FISH) and a bar-coded pyrosequencing approach. Multivariate statistic was used to reveal relationships between sequence diversity and the environmental conditions. The microbial communities were tremendously diverse with a Shannon index of diversity (H') ranging from 6.7 to 7.1. 18,986 sequences could be classified into 37 phyla including candidate divisions, but the full extent of genetic diversity was not captured. While CARD-FISH gave an overview about the community composition, more detailed information was gained by pyrosequencing. Bacteria were more abundant than Archaea. The dominating phylum in all samples was Proteobacteria, especially Betaproteobacteria and Deltaproteobacteria. Furthermore, sequences of Bacteroidetes, Verrucomicrobia, Acidobacteria, Chlorobi, Nitrospira, Spirochaetes, Gammaproteobacteria, Alphaproteobacteria, Chloroflexi, and Gemmatimonadetes were found. The site ammonium concentration, water content and organic matter content revealed to be strongest environmental predictors explaining the observed significant differences in the community composition between sampling sites.
    Systematic and Applied Microbiology 12/2011; 35(1):35-44. · 3.29 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Wastewater treatment often suffers from instabilities and the failure of specific functions such as biological phosphorus removal by polyphosphate accumulating organisms. Since most of the microorganisms involved in water clarification are unknown it is challenging to operate the process accounting for the permanent varying abiotic parameters and the complex composition and unrevealed metabolic capacity of a wastewater microbial community. Fulfilling the demands for water quality irrespective of substrate inflow conditions may emit severe problems if the limited management resources of municipal wastewater treatment plants are regarded. We used flow cytometric analyses of cellular DNA and polyphosphate to create patterns mirroring dynamics in community structure. These patterns were resolved in up to 15 subclusters, the presence and abundances of which correlated with abiotic data. The study used biostatistics to determine the kind and strength of the correlation. Samples investigated were obtained from a primary clarifier and two activated sludge basins. The stability of microbial community structure was found to be high in the basins and low in the primary clarifier. Despite major abiotic changes certain subcommunities were dominantly present (up to 80% stability), whereas others emerged only sporadically (down to 3% stability, both according to equivalence testing). Additionally, subcommunities of diagnostic value were detected showing positive correlation with substrate influxes. For instance blackwater (r(s) = 0.5) and brewery inflow (both r(s) = 0.6) were mirrored by increases in cell abundances in subclusters 1 and 6 as well as 4 and 8, respectively. Phosphate accumulation was obviously positively correlated with nitrate (r(s) = 0.4) and the presence of denitrifying organisms (Rhodacyclaceae). Various other correlations between community structure and abiotic parameters were apparent. The bacterial composition of certain subcommunities was determined by cell sorting and phylogenetic tools like T-RFLP. In essence, we developed a monitoring tool which is quick, cheap and causal in its interpretation. It will make laborious PCR based technique less obligatory as it allows reliable process monitoring and control in wastewater treatment plants.
    Environmental Science & Technology 08/2011; 46(1):84-92. · 5.26 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Modelling of activated sludge processes is a commonly used technique to design and optimize wastewater treatment processes. Since wastewater and activated sludge is characterized by chemical oxygen demand (COD) measurements, units of state variables describing organic matter are expressed as equivalent amounts of COD. However, current procedures for measuring it have several drawbacks, including the production of hazardous wastes, so the utility of other variables for characterizing the organic load in modelling, such as total organic carbon (TOC), warrant re-evaluation. Other advantages of TOC over COD are that it provides matrix-independent analytical results and it can be readily measured online. Proposals for TOC-based models were made in the 1990s, but they seem to have sunk into obscurity. To re-assess the value of TOC for this purpose, we have recalculated the EAWAG module for Bio-P removal coupled to the Activated Sludge Model No. 3 on a TOC basis, and tested it against data acquired in batch experiments with four single carbon sources (acetate, glucose, citrate and casein). The batch test-based calibrations showed a good match with experimental data, following modifications of the model to account for the anaerobic volumes and retention times applied in the tests.
    Bioprocess and Biosystems Engineering 03/2011; 34(3):287-95. · 1.87 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Phase-variable expression of Legionella pneumophila lipopolysaccharide (LPS) has not been described in detail for strains possessing the virulence-associated epitope recognized by the monoclonal antibody (mAb) 3/1 of the Dresden Panel. About 75 % of cases of community-acquired legionellosis are caused by mAb 3/1-positive strains. In this study, the LPS architecture of the mAb 3/1-positive Corby strain was investigated during its life cycle in broth culture and inside monocytic host cells. During the exponential growth phase in broth, the highly acetylated and therefore strongly hydrophobic mAb 3/1 epitope is expressed continuously, but only 3 % of the bacteria can be detected using mAb 59/1, which recognizes a short-chain variant of the Legionella LPS that is less hydrophobic due to missing acetylations of the O-chain. The percentage of mAb 59/1-positive legionellae increases up to 34 % in the post-exponential growth phase. LPS shed in broth during the exponential phase is mAb 59/1-negative, and mAb 3/1-positive components do not possess short-chain molecules. The LPS pattern expressed and shed inside U937 cells and A/J mouse macrophages points to the same regulatory mechanisms. During the so-called 'pregnant pause', the period for establishment of the replicative phagosomes, the mAb 3/1-positive LPS is shed into the phagosome and seems to pass through the phagosomal membrane, while mAb 59/1-positive LPS is detectable only on the bacterial surface. After egress of the legionellae into the cytoplasm followed by host cell lysis, individual bacteria are mAb 3/1-positive and mAb 59/1-negative. Intracellularly formed Legionella clusters consist of surface-located mAb 3/1-positive bacteria, which are predominantly mAb 59/1-negative. They surround less hydrophobic and therefore closely packed mAb 59/1-positive bacteria. Based on the different degrees of hydrophobicity, bacteria are able to support the expression of two functionally different LPS architectures, namely more hydrophobic LPS for surviving in aerosols and more hydrophilic LPS for close-packing of legionellae inside clusters.
    Microbiology 10/2010; 156(Pt 10):2953-61. · 3.06 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Legionella-like isolates, strains W03-356(T), W03-357 and W03-359, from three independent water samples from the river Elbe, Germany, were analysed by using a polyphasic approach. Morphological and biochemical characterization revealed that they were Gram-negative, aerobic, non-spore-forming bacilli with a cut glass colony appearance that grew only on L-cysteine-supplemented buffered charcoal yeast extract agar. Phylogenetic analysis based on sequence comparisons of the 16S rRNA, macrophage infectivity potentiator (mip), gyrase subunit A (gyrA), ribosomal polymerase B (rpoB) and RNase P (rnpB) genes confirmed that the three isolates were distinct from recognized species of the genus Legionella. Phenotypic characterization of strain W03-356(T) based on fatty acid profiles confirmed that it was closely related to Legionella rubrilucens ATCC 35304(T) and Legionella pneumophila ATCC 33152(T), but distinct from other species of the genus Legionella. Serotyping of the isolates showed that they were distinct from all recognized species of the genus Legionella. Strains W03-356(T), W03-357 and W03-359 are thus considered to represent a novel species of the genus Legionella, for which the name Legionella dresdenensis sp. nov. is proposed. The type strain is W03-356(T) (=DSM 19488(T)=NCTC 13409(T)).
    INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY 12/2009; 60(Pt 11):2557-62. · 2.11 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Wastewater treatment plants with enhanced biological phosphorus removal represent a state-of-the-art technology. Nevertheless, the process of phosphate removal is prone to occasional failure. One reason is the lack of knowledge about the structure and function of the bacterial communities involved. Most of the bacteria are still not cultivable, and their functions during the wastewater treatment process are therefore unknown or subject of speculation. Here, flow cytometry was used to identify bacteria capable of polyphosphate accumulation within highly diverse communities. A novel fluorescent staining technique for the quantitative detection of polyphosphate granules on the cellular level was developed. It uses the bright green fluorescence of the antibiotic tetracycline when it complexes the divalent cations acting as a countercharge in polyphosphate granules. The dynamics of cellular DNA contents and cell sizes as growth indicators were determined in parallel to detect the most active polyphosphate-accumulating individuals/subcommunities and to determine their phylogenetic affiliation upon cell sorting. Phylotypes known as polyphosphate-accumulating organisms, such as a "Candidatus Accumulibacter"-like phylotype, were found, as well as members of the genera Pseudomonas and Tetrasphaera. The new method allows fast and convenient monitoring of the growth and polyphosphate accumulation dynamics of not-yet-cultivated bacteria in wastewater bacterial communities.
    Applied and environmental microbiology 02/2009; 75(7):2111-21. · 3.69 Impact Factor
  • Chemie Ingenieur Technik 01/2009; 81(8):1295-1296. · 0.70 Impact Factor
  • S. Salomo, C. Münch, I. Röske
    [Show abstract] [Hide abstract]
    ABSTRACT: The community-level substrate utilization test based on direct incubation of environmental samples in Biolog EcoPlates™ is a suitable and sensitive tool to characterize microbial communities. The aim of this study was to investigate the influence of plant roots and soil structure on the metabolic diversity of microorganisms in a constructed wetland with vertical flow.Sediment samples were taken from different filter depths representing specific filter layers. The color development representing the substrate utilization was measured with the samples over a period of 10 days. The average well color development (AWCD) for all carbon sources was calculated as an indicator of total activity and in order to compensate the influence of the inoculum's density on the color development in the plates. After transformation by dividing by the AWCD, the optical density data were analysed by principal component analysis (PCA). An analysis of the kinetic profile of the AWCD was carried out to increase the analytical power of the method. The corrected data have been successfully fit to the logistic growth equation. Three kinetic model parameters, the asymptote (K), the exponential rate of color change (p) and the time to the midpoint of the exponential portion of the curve (s), were used for statistical analysis of the physiological profile of the microbial community in the different filter layers of the constructed wetland.We found out that in the upper two horizons, which were rooted most densely, mainly easily degradable materials like specific carbohydrates were utilized, while in the lower layers, where only single roots occur, more biochemically inert compounds, e.g. 2-hydroxy benzoic acid, were utilized. Furthermore it could be shown that microorganisms in the surface layer benefited from the plant litter because they can utilize decay products of these. In the lower filter layers specialists took advantage because they had to cope with the biochemically inert materials and the lower nutrient supply.
    Water Research 01/2009; · 4.66 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Analysis of environmental bacteria on the single cell level often requires fixation to store the cells and to keep them in a state as near life-like as possible. Fixation procedures should furthermore counteract the increase of autofluorescence, cell clogging, and distortion of surface characteristics. Additionally, they should meet the specific fixation demands of both aerobically and anaerobically grown bacteria. A fixation method was developed based on metal solutions in combination with sodium azide. The fixation efficiencies of aluminium, barium, bismuth, cobalt, molybdenum, nickel, and tungsten salts were evaluated by flow cytometric measurement of the DNA contents as a bacterial population/community stability marker. Statistical equivalence testing was involved to permit highly reliable flow cytometric pattern evaluation. Investigations were carried out with pure cultures representing environmentally important metabolic and respiratory pathways as controls and with activated sludge as an example for highly diverse bacterial communities. A mixture of 5 mM barium chloride and nickel chloride, each and 10% sodium azide was found to be a suitable fixative for all tested bacteria. The described method provided good sample stability for at least 9 days.
    Journal of Microbiological Methods 06/2008; 75(1):127-34. · 2.16 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this study, catalyzed reporter deposition in situ hybridization (CARD—ISH) with tetramethylbenzidine (TMB) was used for rapid detection of the food pathogens Salmonella typhimurium and Escherichia coli. The bacteria in a sample were concentrated by membrane filtration. The filter membranes with the cells thus removed were incubated on nutrient agar for 4–5h to allow the formation of microcolonies. Instead of fluorescent tyramide, 3,3′,5,5′-tetramethylbenzidine (TMB), which yields a blue precipitate, was used for signal amplification after in situ hybridization. Microcolonies amplified with TMB produced blue signals, which were sufficiently intense to allow visual evaluation either using a stereomicroscope, or even with the naked eye. Therefore even low cell numbers of hygienically critical bacteria can be detected on the filter membrane without a protracted examination. This enables the detection of low cell numbers (<10cfu) in a sample of 100ml tap water within 9–10h.
    European Food Research and Technology 01/2008; 227(4):995-999. · 1.44 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Sediments in standing waters are complex habitats that are able to provide favorable living conditions for manifold microbial species. The aim of this study was to investigate the spatial and seasonal composition of bacteria in freshwater sediments and the chemical conditions. Four sampling points were investigated at monthly intervals along the flow of water from a pre-reservoir down to the main dam of the Saidenbach reservoir, a drinking water reservoir located in Saxony, Germany. Selected chemical criteria of the sediments were analyzed, as well as the physical conditions of the water body at the chosen sites. Redox-sensitive chemical criteria, such as nitrogen, sulfur, iron and manganese compounds displayed very steep vertical gradients within the sediment. Phylogenetic composition of the communities was investigated utilizing clone libraries and catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH). Up to 90% of the cells that were stained with propidium iodide hybridized with probes for Bacteria and Archaea. This amount decreased with sediment depth. The predominant bacterial groups found in the sediment were α-Proteobacteria, especially at the sampling point with a high content of planktogenic organic material closest to the main dam, as well as β-Proteobacteria and the Cytophaga–Flavobacterium cluster. Clone libraries allowed a more detailed view of the microbial diversity within the detected phylogenetic groups. Despite an observed variation of α-Proteobacteria and bacteria belonging to the Cytophaga–Flavobacterium cluster, a regression analysis showed very weak multiple correlation coefficients between chemical criteria and the analyzed broad phylogenetic bacterial groups.
    Limnologica. 01/2008; 38(3):367-377.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The occurrence of taste and odor problems in drinking water supplies is a widespread phenomenon. From a Saxonian water reservoir we isolated a cyanobacterial species which was classified as Phormidium sp. Under laboratory conditions it produced an earthy-musty smell due to the synthesis of geosmin. The only genes shown to be involved in geosmin biosynthesis are cyc2 and geoA of Streptomyces. Based on the alignment of Cyc2 with a putative sesquiterpene synthase of Nostoc punctiforme, a degenerate primer pair was designed. By PCR, we could amplify two similar genes in Phormidium sp., which we named geoA1 and geoA2. Their expression was studied by reverse transcription-PCR. This revealed that both genes are expressed at 20 degrees C and a light-dark cycle of 12 h. Expression was not detectable at the end of a 24-h dark period. To analyze the prevalence of geoA1 and geoA2 in samples from the phytobenthos, we generated PCR fragments with the same degenerate primer pair. Fifty-five different sequences that might represent geoA variants were obtained. The GC content ranged from 42% to 67%, suggesting that taxonomically very different bacteria might contain such genes.
    Applied and Environmental Microbiology 12/2007; 73(21):6988-93. · 3.68 Impact Factor
  • Ch Münch, T Neu, P Kuschk, I Röske
    [Show abstract] [Hide abstract]
    ABSTRACT: It was the goal of the investigations to characterise the biofilm on the plant roots because of the demonstrable major role of these associated bacteria. The essential criteria for the research were to look at the structure of the microbial colonisation (pattern, density) and to determine properties of the rhizoplane biofilm such as thickness and structure. The root material from a hydroponic system, planted with Glyceria maxima and used for nitrogen removal, has been used for the investigations. Several properties of the bacteria became visible due to the application of specific dyes. The evaluation of the samples was performed by scanning confocal laser microscopy (CLSM). It was shown that the microbial colonisation of the root surface of Glyceria maxima was on an unexpected high level and seems to be related mainly to the permeability and therefore to the age of the plant roots. The thickness of the rhizoplane biofilm is remarkably thin; no inactive layers could be observed in contrast to biofilm growing on technical carrier material. Caused by the untypically two-sided supply with nutrients the whole biofilm is in interaction with the surroundings. This indicates the importance of the plant roots for the microbial transformation processes in wetlands and underlines the especialness of the root as carrier for microorganisms.
    Water Science & Technology 02/2007; 56(3):271-6. · 1.10 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Activated sludge systems can be operated to select bacteria which accumulate phosphorus as polyphosphate. By these means, phosphate can be removed without the addition of chemical precipitants. This contribution presents results of experiments with a bench-scale purification plant for domestic sewage. The goal was to find the concentrations of relevant metal cations at which the biological P removal may be affected by competing chemical (precipitation) or physical (adsorption) processes. For this goal, increasing amounts of iron and calcium, respectively, were added into the pilot plant.During the addition of iron, the proportion of chemically (iron-) bound phosphorus increased from 10 to more than 50%. The P-release rate substantially decreased with increasing amount of added iron. An addition of small amounts of iron enhanced the long-term stability of the P elimination as a whole.During the experimental period with addition of calcium, the proportion of Ca-bound phosphorus increased from 1 to 2% to almost 15%. In batch experiments a measurable Ca-phosphate precipitation took place at a pH value of at least 8.0 and a Ca-concentration of at least 100 mg/l. The increase in hardness of the influent waste water didn't produce any positive effect on the stability of the enhanced biological phosphorus removal.The metal ions Ca2+, Mg2+ and K+ serve as counter-ions in the polyhosphate chains. They were identified and quantified by X-ray spectrometry in combination with scanning transmission electron microscopy. A release of Mg2+ and K+ occured simultaneously with the degration of polyphosphates (PP). The PP bound to Ca was not redox sensitive.
    Internationale Revue der gesamten Hydrobiologie und Hydrographie 01/2007; 80(4):605 - 621.
  • Frank Kloep, Werner Manz, Isolde Röske
    [Show abstract] [Hide abstract]
    ABSTRACT: The microbial communities of three different habitat types and from two sediment depths in the River Elbe were investigated by fluorescence in situ hybridization at various levels of complexity. Differences in the microbial community composition of free-flowing river water, water within the hyporheic interstitial and sediment-associated bacteria were quantitatively analyzed using domain- and group-specific oligonucleotide probes. Qualitative data on the presence/absence of specific bacterial taxa were gathered using genus- and species-specific probes. The complete data set was statistically processed by univariate statistical approaches, and two-dimensional ordinations of nonmetric multidimensional scaling. The analysis showed: (1) that the resolution of microbial community structures at microenvironments, habitats and locations can be regulated by targeted application of oligonucleotides on phylogenetic levels ranging from domains to species, and (2) that an extensive qualitative presence/absence analysis of multiparallel hybridization assays enables a fine-scale apportionment of spatial differences in microbial community structures that is robust against apparent limitations of fluorescence in situ hybridization such as false positive hybridization signals or inaccessibility of in situ oligonucleotide probes. A general model for the correlation of the phylogenetic depth of focus and the relative spatial resolution of microbial communities by fluorescence in situ hybridization is presented.
    FEMS Microbiology Ecology 05/2006; 56(1):79-94. · 3.56 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To evaluate the occurrence and abundance of phages that carry the stx(1) and stx(2) gene in water samples of different quality. Phages growing on the Shiga toxin-negative Escherichia coli O157:H7 (ATCC 43,888) strain were enumerated by a plaque assay in concentrated raw and treated waste water samples and river water samples. Plaques were investigated for the presence of stx(1) and stx(2) genes by a multiplex/nested PCR procedure. An overall number of 805 plaques were tested for the presence of stx-carrying phages. Stx genes could be demonstrated in 2% (stx(1)) and 16% (stx(2)) of the plaques. Stx-phages were eliminated with approximately the same efficiency in comparison with somatic coliphages during the waste water treatment process. Due to the low numbers of phages carrying the stx genes 1 and 2 in treated waste water and river water, the dilution and inactivation of host bacteria and the unsuitable conditions for the transduction of host organisms in aquatic environments, it is difficult to derive from the data the direct evidence for a public health problem. The results show the quantitative occurrence of stx-carrying phages in waste and river water and confirm the frequent circulation of these viruses in the aquatic environment.
    Letters in Applied Microbiology 02/2006; 42(1):48-53. · 1.63 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Sediment samples from four reservoirs of different trophic state were compared with regard to chemical gradients in the pore water, composition of microbial communities and extracellular enzyme activities. The trophic state was clearly reflected by steep vertical concentration gradients of ammonium and alkalinity in the pore water. A high concentration of these parameters indicated a high microbial in situ activity in the more eutrophic reservoirs. However, the total number of bacteria in sediments seemed hardly to be influenced by the trophic conditions in the water column. Differences in the microbial composition of the sediments became evident by comparative 16S rDNA analysis of extracted DNA and by fluorescence in situ hybridization. Although a high proportion of the cells detectable with the EUB probe could not be identified at the subdomain level, members of the β-Proteobacteria constituted an important fraction in the sediments of the more eutrophic reservoirs, whereas γ-subgroup Proteobacteria were most frequently detected in sediment samples from the dystrophic Muldenberg reservoir. The assessment of extracellular enzyme activities (esterases, phosphatases, glucosidases and aminopeptidases, respectively) in sediment samples of the four reservoirs revealed specific patterns of metabolic potentials in accordance with the trophic state and characteristics of the catchment.
    FEMS Microbiology Ecology 01/2006; 46(3):331 - 347. · 3.56 Impact Factor

Publication Stats

362 Citations
62.97 Total Impact Points

Institutions

  • 2011
    • Sächsische Akademie der Wissenschaften zu Leipzig
      Leipzig, Saxony, Germany
  • 2000–2011
    • Technische Universität Dresden
      • Institute for Microbiology
      Dresden, Saxony, Germany
  • 2007
    • Leibniz Institute for Solid State and Materials Research Dresden
      Dresden, Saxony, Germany