Analysis of the flow field induced by the sessile peritrichous ciliate Opercularia asymmetrica

Hartmann, C.; Özmutlu, Özlem; Petermeier, Hannes; Fried, J.; Delgado, Antonio

doi:10.1016/j.jbiomech.2005.11.006

Cited by 33 publications

(49 citation statements)

References 17 publications

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“…Several studies on fungi and protozoa in activated sludge systems in general demonstrated that these eukaryotic organisms fulfill a wide variety of important tasks in the biomass conversion and water clarification processes (10,19,21,33,35). It is known that protozoa or fungi are involved in the formation, structure and function of biofilms for several biofilm systems besides wastewater treatment (22). In preliminary observations of granular biofilms, we found stalked ciliates and, in some cases, fungi to be present in high numbers.…”

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confidence: 70%

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Microbial Composition and Structure of Aerobic Granular Sewage Biofilms

Weber

Ludwig

Schleifer

et al. 2007

Appl Environ Microbiol

168

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Aerobic activated sludge granules are dense, spherical biofilms which can strongly improve purification efficiency and sludge settling in wastewater treatment processes. In this study, the structure and development of different granule types were analyzed. Biofilm samples originated from lab-scale sequencing batch reactors which were operated with malthouse, brewery, and artificial wastewater. Scanning electron microscopy, light microscopy, and confocal laser scanning microscopy together with fluorescence in situ hybridization (FISH) allowed insights into the structure of these biofilms. Microscopic observation revealed that granules consist of bacteria, extracellular polymeric substances (EPS), protozoa and, in some cases, fungi. The biofilm development, starting from an activated sludge floc up to a mature granule, follows three phases. During phase 1, stalked ciliated protozoa of the subclass Peritrichia, e.g., Epistylis spp., settle on activated sludge flocs and build tree-like colonies. The stalks are subsequently colonized by bacteria. During phase 2, the ciliates become completely overgrown by bacteria and die. Thereby, the cellular remnants of ciliates act like a backbone for granule formation. During phase 3, smooth, compact granules are formed which serve as a new substratum for unstalked ciliate swarmers settling on granule surfaces. These mature granules comprise a dense core zone containing bacterial cells and EPS and a loosely structured fringe zone consisting of either ciliates and bacteria or fungi and bacteria. Since granules can grow to a size of up to several millimeters in diameter, we developed and applied a modified FISH protocol for the study of cryosectioned biofilms. This protocol allows the simultaneous detection of bacteria, ciliates, and fungi in and on granules.During the last 20 years, intensive research in the field of biological wastewater treatment and other applications has demonstrated that biofilms are often more efficient for water purification than suspended activated sludge. Today, the application of anaerobic and aerobic granular sludge in wastewater treatment is regarded as one of the most useful and promising biotechnologies. Granular sludge was described first for strictly anaerobic systems (26). In the late 1990s, the formation and application of aerobic granules was reported (30). Such granules are spherical compact aggregates of microorganisms, mainly bacteria, and extracellular polymeric substances (EPS). Granules can be described as "biofilm in suspension" and are considered to be a special case of biofilm formation, composed of self-immobilized cells (9,16,20). The application of granules for wastewater treatment shows many advantages. An outstanding feature is the excellent settleability (high settling velocity), which is a prerequisite to handle high liquid flows. Moreover, granular sludge provides high and stable rates of metabolism, resilience to shocks and toxins due to protection by a matrix of EPS (40), long biomass residence times, biomass immobilization i...

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confidence: 70%

“…3B and 4). This colonization was additionally enhanced by the cilia beat of the ciliates, which provide a continuous nutrient flux toward the biofilm (19,22). After a few days, several hundred ciliate cells covered the surface of each floc.…”

Section: Resultsmentioning

confidence: 99%

Microbial Composition and Structure of Aerobic Granular Sewage Biofilms

Weber

Ludwig

Schleifer

et al. 2007

Appl Environ Microbiol

168

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“…The stimulation of sessile HF up to day 10 can on one hand be explained by competition, since benthivorous, bacterivorous ciliates (e.g., scuticociliates like Cinetochilum margaritaceum and Cyclidium glaucoma, but also prostomatids [17]) were abundant at all times. On the other hand, suspension feeding ciliates, like the sessile peritrichs, whirl down bacteria from the plankton (18,22), while gliding ciliates can whirl loosely attached cells up from the biofilm by body movement or filter feeding (15), therefore probably supporting sessile HF, which can in turn filter them from the planktonic phase. After day 10, predation by haptorids (like Acineria uncinata [17]) could be responsible for further declines in numbers of gliding HF.…”

Section: Figmentioning

confidence: 99%

Seasonal and Successional Influences on Bacterial Community Composition Exceed That of Protozoan Grazing in River Biofilms

Wey

Jürgens

Weitere

2012

Appl Environ Microbiol

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The effects of protozoa (heterotrophic flagellates and ciliates) on the morphology and community composition of bacterial biofilms were tested under natural background conditions by applying size fractionation in a river bypass system. Confocal laser scanning microscopy (CLSM) was used to monitor the morphological structure of the biofilm, and fingerprinting methods (single-stranded conformation polymorphism [SSCP] and denaturing gradient gel electrophoresis [DGGE]) were utilized to assess changes in bacterial community composition. Season and internal population dynamics had a greater influence on the bacterial biofilm than the presence of protozoa. Within this general framework, bacterial area coverage and microcolony abundance were nevertheless enhanced by the presence of ciliates (but not by the presence of flagellates). We also found that the richness of bacterial operational taxonomic units was much higher in planktonic founder communities than in the ones establishing the biofilm. Within the first 2 h of colonization of an empty substrate by bacteria, the presence of flagellates additionally altered their biofilm community composition. As the biofilms matured, the number of bacterial operational taxonomic units increased when flagellates were present in high abundances. The additional presence of ciliates tended to at first reduce (days 2 to 7) and later increase (days 14 to 29) bacterial operational taxonomic unit richness. Altogether, the response of the bacterial community to protozoan grazing pressure was small compared to that reported in planktonic studies, but our findings contradict the assumption of a general grazing resistance of bacterial biofilms toward protozoa.

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“…[5][6][7][8][9][10][11][12] However, to our knowledge, a three-dimensional ͑3D͒ velocimetry method to measure the flows generated by microorganisms has not yet been reported. The dimensions of the measurements have been limited to two-dimensional ͑2D͒ two components.…”

Section: Introductionmentioning

confidence: 99%

“…[6][7][8][9][10][11][12] The first method is particle tracking velocimetry ͑PTV͒, a technique to measure the velocity of a flow-driven particle. Sleigh and Aiello applied PTV to microorganisms and followed the movement of water around the cilia of Vorticella 6 and Stentor 7 by tracing the motion of latex particles with a frame-by-frame analyses of cine films obtained with microscope and a high speed camera.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional two-component velocity measurement of the flow field induced by the Vorticella picta microorganism using a confocal microparticle image velocimetry technique

et al. 2009

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Understanding the biological feeding strategy and characteristics of a microorganism as an actuator requires the detailed and quantitative measurement of flow velocity and flow rate induced by the microorganism. Although some velocimetry methods have been applied to examine the flow, the measured dimensions were limited to at most two-dimensional two-component measurements. Here we have developed a method to measure three-dimensional two-component flow velocity fields generated by the microorganism Vorticella picta using a piezoscanner and a confocal microscope. We obtained the two-component velocities of the flow field in a two-dimensional plane denoted as the XY plane, with an observation area of 455ϫ 341 m 2 and the resolution of 9.09 m per each velocity vector by a confocal microparticle image velocimetry technique. The measurement of the flow field at each height took 37.5 ms, and it was repeated in 16 planes with a 2.50 m separation in the Z direction. We reconstructed the three-dimensional twocomponent flow velocity field. From the reconstructed data, the flow velocity field ͓u ͑x,y,z͒ , v ͑x,y,z͒ ͔ in an arbitrary plane can be visualized. The flow rates through YZ and ZX planes were also calculated. During feeding, we examined a suction flow to the mouth of the Vorticella picta and measured it to be to 300 pl/s.

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Analysis of the flow field induced by the sessile peritrichous ciliate Opercularia asymmetrica

Cited by 33 publications

References 17 publications

Microbial Composition and Structure of Aerobic Granular Sewage Biofilms

Microbial Composition and Structure of Aerobic Granular Sewage Biofilms

Seasonal and Successional Influences on Bacterial Community Composition Exceed That of Protozoan Grazing in River Biofilms

Three-dimensional two-component velocity measurement of the flow field induced by the Vorticella picta microorganism using a confocal microparticle image velocimetry technique

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