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  • 1
    Language: English
    In: The Science of the Total Environment, Feb 15, 2015, Vol.506-507, p.353(8)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.scitotenv.2014.11.043 Byline: Norbert Kamjunke, Peter Herzsprung, Thomas R. Neu Abstract: Streams and rivers are important sites of organic carbon mineralization which is dependent on the land use within river catchments. Here we tested whether planktonic and epilithic biofilm bacteria differ in their response to the quality of dissolved organic carbon (DOC). Thus, planktonic and biofilm bacterial production was compared with patterns of DOC along a land-use gradient in the Bode catchment area (Germany). The freshness index of DOC was positively related to the proportion of agricultural area in the catchment. The humification index correlated with the proportion of forest area. Abundance and production of planktonic bacteria were lower in headwaters than at downstream sites. Planktonic production was weakly correlated to the total concentration of DOC but more strongly to quality-measures as revealed by spectra indexes, i.e. positively to the freshness index and negatively to the humification index. In contrast to planktonic bacteria, abundance and production of biofilm bacteria were independent of DOC quality. This finding may be explained by the association of biofilm bacteria with benthic algae and an extracellular matrix which represent additional substrate sources. The data show that planktonic bacteria seem to be regulated at a landscape scale controlled by land use, whereas biofilm bacteria are regulated at a biofilm matrix scale controlled by autochthonous production. Thus, the effects of catchment-scale land use changes on ecosystem processes are likely lower in small streams dominated by biofilm bacteria than in larger streams dominated by planktonic bacteria. Article History: Received 4 September 2014; Revised 11 November 2014; Accepted 11 November 2014 Article Note: (miscellaneous) Editor: C.E.W. Steinberg
    Keywords: Bacteria
    ISSN: 0048-9697
    Source: Cengage Learning, Inc.
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  • 2
    In: Biotechnology and Bioengineering, December 2013, Vol.110(12), pp.3104-3113
    Description: A microbial fuel cell was fed with anoxic groundwater from a field site contaminated with benzene and sulfide. Monitoring of power generation demonstrated that groundwater microorganisms utilized the anode as an artificial electron acceptor for benzene and sulfide removal. Furthermore, the degradation process underlying benzene removal and the anodic microbial community were investigated using stable isotope tools and pyrosequencing of 16S rRNA genes, respectively.
    Keywords: Benzene Degradation ; Contaminated Groundwater ; Microbial Fuel Cell ; Pyrosequencing ; Stable Isotope Analysis
    ISSN: 0006-3592
    E-ISSN: 1097-0290
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  • 3
    Language: English
    In: Water Research, 2017, Vol.122, pp.urn:issn:0043-1354
    Description: A new acid soluble extracellular polymeric substance (acid soluble EPS) was extracted from an acetate fed aerobic granular sludge reactor operated at 35 °C. Acid soluble EPS dominated granules exhibited a remarkable and distinctive tangled tubular morphology. These granules are dominated by Defluviicoccus...
    Keywords: Aerobic Granular Sludge ; Biofilm ; Defluviicoccus ; Eps Extraction ; Extracellular Polymeric Substances
    ISSN: 0043-1354
    Source: NARCIS (National Academic Research and Collaborations Information System)
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  • 4
    Language: English
    In: Science of the Total Environment, 15 February 2015, Vol.506-507, pp.353-360
    Description: Streams and rivers are important sites of organic carbon mineralization which is dependent on the land use within river catchments. Here we tested whether planktonic and epilithic biofilm bacteria differ in their response to the quality of dissolved organic carbon (DOC). Thus, planktonic and biofilm bacterial production was compared with patterns of DOC along a land-use gradient in the Bode catchment area (Germany). The freshness index of DOC was positively related to the proportion of agricultural area in the catchment. The humification index correlated with the proportion of forest area. Abundance and production of planktonic bacteria were lower in headwaters than at downstream sites. Planktonic production was weakly correlated to the total concentration of DOC but more strongly to quality-measures as revealed by spectra indexes, i.e. positively to the freshness index and negatively to the humification index. In contrast to planktonic bacteria, abundance and production of biofilm bacteria were independent of DOC quality. This finding may be explained by the association of biofilm bacteria with benthic algae and an extracellular matrix which represent additional substrate sources. The data show that planktonic bacteria seem to be regulated at a landscape scale controlled by land use, whereas biofilm bacteria are regulated at a biofilm matrix scale controlled by autochthonous production. Thus, the effects of catchment-scale land use changes on ecosystem processes are likely lower in small streams dominated by biofilm bacteria than in larger streams dominated by planktonic bacteria.
    Keywords: Bacterial Production ; Doc ; Freshness Index ; Humification Index ; Biofilm ; Confocal Laser Scanning Microscopy (Clsm) ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 5
    Language: English
    In: PLoS ONE, 01 January 2011, Vol.6(11), p.e26404
    Description: We investigated the ability of bacterial communities to colonize and dissolve two biogenic carbonates (Foraminifera and oyster shells). Bacterial carbonate dissolution in the upper water column is postulated to be driven by metabolic activity of bacteria directly colonising carbonate surfaces and the subsequent development of acidic microenvironments. We employed a combination of microsensor measurements, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and image analysis and molecular documentation of colonising bacteria to monitor microbial processes and document changes in shell surface topography. Bacterial communities rapidly colonised shell surfaces, forming dense biofilms with extracellular polymeric substance (EPS) deposits. Despite this, we found no evidence of bacterially mediated carbonate dissolution. Dissolution was not indicated by Ca²⁺ microprofiles, nor was changes in shell surface structure related to the presence of colonizing bacteria. Given the short time (days) settling carbonate material is actually in the twilight zone (500-1000 m), it is highly unlikely that microbial metabolic activity on directly colonised shells plays a significant role in dissolving settling carbonates in the shallow ocean.
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
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  • 6
    In: Limnology and Oceanography, July 2011, Vol.56(4), pp.1386-1398
    Description: We studied the formation of iron‐rich particles at steeply opposing gradients of oxygen and Fe(II) within the redoxcline of an acidic lignite mine lake (pH 2.9). Particles formed had a diameter of up to 380 μm, showed high sedimentation velocity (∼ 2 m h), and were dominated by the iron mineral schwertmannite. Although the particles were highly colonized by microbial cells (∼ 10 cells [g dry weight]), the organic carbon content was below 11%. Bathymetry and the inflow of less acidic, Fe(II)‐rich groundwater into the northern basin of the lake results in two distinct mixing regimes in the same lake. The anoxic monimolimnion of the northern basin had higher pH, Fe(II), dissolved organic carbon, and CO values compared with the more central basin. Particles formed in the northern basin differed in color, were smaller, had higher organic carbon contents, but were still dominated by schwertmannite. Microcosm incubations revealed the dominance of microbial Fe(II) oxidation. Comparison of bacterial clone libraries suggested that pH was a major driving force, shaping the microbial communities responsible for the oxidation of Fe(II) in both basins. Acidophilic spp. and Chlorobia‐related bacteria were present in the central basin, whereas neutrophilic spp. dominated the northern basin. Snow‐like particles had a high sinking velocity and acted as a carrier for organic carbon, microorganisms, trace metals, and Fe(III) to the sediment. Because these particles are fundamentally different from organic‐rich “snows” from lakes, rivers, and oceans, we propose a new term, “iron snow.”
    ISSN: 0024-3590
    E-ISSN: 1939-5590
    Source: John Wiley & Sons, Inc.
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  • 7
    Language: English
    In: Environmental Pollution, April 2016, Vol.211, pp.271-281
    Description: Ethylbenzene and toluene degradation under nitrate-, Mn(IV)-, or Fe(III)-reducing conditions was investigated by compound specific stable isotope analysis (CSIA) using three model cultures ( EbN1, G5G6, and a -dominated mixed culture). Systematically lower isotope enrichment factors for carbon and hydrogen were observed for particulate Mn(IV). The increasing diffusion distances of toluene or ethylbenzene to the solid Mn(IV) most likely caused limited bioavailability and hence resulted in the observed masking effect. The data suggests further ethylbenzene hydroxylation by ethylbenzene dehydrogenase (EBDH) and toluene activation by benzylsuccinate synthase (BSS) as initial activation steps. Notably, significantly different values in dual isotope analysis were detected for toluene degradation by under the three studied redox conditions, suggesting variations in the enzymatic transition state depending on the available TEA. The results indicate that two-dimensional CSIA has significant potential to assess anaerobic biodegradation of ethylbenzene and toluene at contaminated sites.
    Keywords: Dual Isotope Analysis ; Isotope Fractionation ; Manganese Reduction ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 8
    Language: English
    In: Water Research, 01 October 2016, Vol.102, pp.63-72
    Description: This study aimed at identifying how to improve the level of permeate flux stabilisation during gravity-driven membrane filtration without control of biofilm formation. The focus was therefore on understanding (i) how the different fractions of the biofilms (inorganics particles, bacterial cells, EPS matrix) influence its hydraulic resistance and (ii) how the compression of biofilms impacts its hydraulic resistance, i.e., can water head be increased to increase the level of permeate flux stabilisation. Biofilms were developed on ultrafiltration membranes at 88 and 284 cm water heads with dead-end filtration for around 50 days. A larger water head resulted in a smaller biofilm permeability (150 and 50 L m  h  bar for biofilms grown at 88 cm and 284 cm water head, respectively). Biofilms were mainly composed of EPS (〉90% in volume). The comparison of the hydraulic resistances of biofilms to model fouling layers indicated that most of the hydraulic resistance is due to the EPS matrix. The compressibility of the biofilm was also evaluated by subjecting the biofilms to short-term (few minutes) and long-term variations of transmembrane pressures (TMP). A sudden change of TMP resulted in an instantaneous and reversible change of biofilm hydraulic resistance. A long-term change of TMP induced a slow change in the biofilm hydraulic resistance. Our results demonstrate that the response of biofilms to a TMP change has two components: an immediate variation of resistance (due to compression/relaxation) and a long-term response (linked to biofilm adaptation/growth). Our results provide relevant information about the relationship between the operating conditions in terms of TMP, the biofilm structure and composition and the resulting biofilm hydraulic resistance. These findings have practical implications for a broad range of membrane systems.
    Keywords: Biofilm ; Permeability ; Hydraulic Resistance ; Compression ; Extracellular Polymeric Substances (EPS) ; Ultrafiltration Membrane ; Engineering
    ISSN: 0043-1354
    E-ISSN: 1879-2448
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  • 9
    Language: English
    In: Water Research, 15 December 2017, Vol.127, pp.211-222
    Description: Previous laboratory and on-site experiments have highlighted the importance of hydrodynamics in shaping biofilm composition and architecture. In how far responses to hydrodynamics can be found in natural flows under the complex interplay of environmental factors is still unknown. In this study we investigated the effect of near streambed turbulence in terms of turbulent kinetic energy (TKE) on the composition and architecture of biofilms matured in two mountainous streams differing in dissolved nutrient concentrations. Over both streams, TKE significantly explained 7% and 8% of the variability in biofilm composition and architecture, respectively. However, effects were more pronounced in the nutrient richer stream, where TKE significantly explained 12% and 3% of the variability in biofilm composition and architecture, respectively. While at lower nutrient concentrations seasonally varying factors such as stoichiometry of dissolved nutrients (N/P ratio) and light were more important and explained 41% and 6% of the variability in biofilm composition and architecture, respectively. Specific biofilm features such as elongated ripples and streamers, which were observed in response to the uniform and unidirectional flow in experimental settings, were not observed. Microbial biovolume and surface area covered by the biofilm canopy increased with TKE, while biofilm thickness and porosity where not affected or decreased. These findings indicate that under natural flows where near bed flow velocities and turbulence intensities fluctuate with time and space, biofilms became more compact. They spread uniformly on the mineral surface as a film of densely packed coccoid cells appearing like cobblestone pavement. The compact growth of biofilms seemed to be advantageous for resisting hydrodynamic shear forces in order to avoid displacement. Thus, near streambed turbulence can be considered as important factor shaping the composition and architecture of biofilms grown under natural flows.
    Keywords: Bacteria ; Cyanobacteria ; Algae ; AAL-Specific Glycoconjugates ; Near Streambed Turbulence ; Engineering
    ISSN: 0043-1354
    E-ISSN: 1879-2448
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  • 10
    Language: English
    In: Applied microbiology and biotechnology, 2015, Vol.99(17), pp.7343-7356
    Description: Biofilms are surface-associated colonies of microorganisms embedded in a matrix of extracellular polymeric substances (EPS). As EPS mediate the contact between cells and surfaces, an understanding of their composition and production is of particular interest. In this study, the EPS components of Sulfolobus metallicus DSM 6482ᵀ forming biofilms on elemental sulfur (S⁰) were investigated by confocal laser scanning microscopy (CLSM). In order to visualize cell and EPS distributions, biofilm cells were stained with various dyes specific for glycoconjugates, proteins, nucleic acids and lipids. Biofilm cells on S⁰ were heterogeneously distributed and characterized as individual cells, microcolonies, and large clusters up to a hundred micrometers in diameter. The glycoconjugates in biofilms were detected by fluorescence lectin-binding analysis (FLBA). Screening of 72 commercially available lectins resulted in the selection of 21 lectins useful for staining biofilms of S. metallicus ᵀ. Capsular EPS from planktonic cells were mainly composed of carbohydrates and proteins. In contrast, colloidal EPS from planktonic cells were dominated by carbohydrates. Proteins were found to be major components in EPS from biofilms on S⁰. Using specific probes combined with CLSM, we showed that extracellular proteins and nucleic acids were present in the EPS matrix. Finally, we showed that S. metallicus ᵀ cells were embedded in a flexible EPS matrix. This study provides new insights into archaeal biofilms and EPS composition and properties with respect to their interactions with S⁰. ; p. 7343-7356.
    Keywords: Lipids ; Lectins ; Sulfolobus ; Confocal Laser Scanning Microscopy ; Dyes ; Extracellular Matrix ; Glycoconjugates ; Screening ; Nucleic Acids ; Biofilm ; Fluorescence ; Sulfur ; Proteins ; Microorganisms
    ISSN: 0175-7598
    E-ISSN: 14320614
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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