Optically Transparent Porous Medium for Nondestructive Studies of Microbial Biofilm Architecture and Transport Dynamics

Leis, Andrew; Schlicher, Sven; Franke, H.; Strathmann, Martin

doi:10.1128/aem.71.8.4801-4808.2005

Cited by 64 publications

(64 citation statements)

References 49 publications

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“…The empirical parameter γ can be used to quantify the important role of macroscopic hydrodynamic and chemical effects on clogging ( Figure 5), but continued progress toward a mechanistic understanding of deposit morphology, extending the work of Veerapaneni and Wiesner (36), will require experimental techniques that non-invasively quantify deposit structure (e.g. , 39,40 ). This effort, in turn, would provide the basis for improved pore-scale clogging models.…”

Section: Hydrodynamic Shearmentioning

confidence: 99%

Hydrodynamic and Chemical Factors in Clogging by Montmorillonite in Porous Media

Mays

2007

Environ. Sci. Technol.

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Clogging by colloid deposits is important in water treatment filters, groundwater aquifers, and petroleum reservoirs. The complexity of colloid deposition and deposit morphology preclude models based on first principles, so this study extends an empirical approach to quantify clogging using a simple, one-parameter model. Experiments were conducted with destabilized suspensions of sodiumand calcium-montmorillonite to quantify the hydrodynamic and chemical factors important in clogging. Greater clogging is observed at slower fluid velocity, consistent with previous investigations. However, calcium-montmorillonite causes one order of magnitude less clogging per mass of deposited particles compared to sodium-montmorillonite or a previously published summary of clogging in model granular media. Steady state conditions, in which the permeability and the quantity of deposited material are both constant, were not observed, even though the experimental conditions were optimized for that purpose. These results indicate that hydrodynamic aspects of clogging by these natural materials are consistent with those of simplified model systems, and they demonstrate significant chemical effects on clogging for fully destabilized montmorillonite clay.

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Section: Hydrodynamic Shearmentioning

confidence: 99%

Hydrodynamic and Chemical Factors in Clogging by Montmorillonite in Porous Media

Mays

2007

Environ. Sci. Technol.

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“…To manufacture a 3D porous material that is geometrically similar to soil, we used granules made from the fluoropolymer Nafion, which is transparent in water and thus allows microscopic imaging deep inside the porous material (47). Nafion granules were generated from dissolved Nafion (Ion Power).…”

Section: Methodsmentioning

confidence: 99%

Biofilm streamers cause catastrophic disruption of flow with consequences for environmental and medical systems

Drescher

Shen

Bassler

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

306

396

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Biofilms are antibiotic-resistant, sessile bacterial communities that occupy most moist surfaces on Earth and cause chronic and medical device-associated infections. Despite their importance, basic information about biofilm dynamics in common ecological environments is lacking. Here, we demonstrate that flow through soil-like porous materials, industrial filters, and medical stents dramatically modifies the morphology of Pseudomonas aeruginosa biofilms to form 3D streamers, which, over time, bridge the spaces between obstacles and corners in nonuniform environments. We discovered that accumulation of surface-attached biofilm has little effect on flow through such environments, whereas biofilm streamers cause sudden and rapid clogging. We demonstrate that flow-induced shedding of extracellular matrix from surface-attached biofilms generates a sievelike network that captures cells and other biomass, which add to the existing network, causing exponentially fast clogging independent of growth. These results suggest that biofilm streamers are ubiquitous in nature and strongly affect flow through porous materials in environmental, industrial, and medical systems.bioclogging | biofouling | porous media I n the laboratory, bacteria are usually grown as planktonic cells in shaken suspensions, which differs dramatically from the natural environments of most microbes. In their natural habitats, bacteria often live in biofilms (1-3), which are tightly packed, surface-associated assemblies of bacteria that are bound together by extracellular polymeric substances (4, 5). Although biofilms are desirable in waste-water treatment (6), biofilms primarily cause undesirable effects such as chronic infections or clogging of industrial flow systems (1-3). Cells in biofilms display many behavioral differences from planktonic cells, such as a 1,000-fold increase in tolerance to antibiotics (7,8), an altered transcriptome (9-11), and spatially heterogeneous metabolic activity (12, 13). Some of these physiological peculiarities of biofilm-dwelling cells may be due to strong gradients of nutrients and metabolites, which also affect biofilm morphology and composition (14, 15). However, little is known about how physical aspects of the environment affect biofilm dynamics.The opportunistic pathogen Pseudomonas aeruginosa has become a model organism for biofilm studies largely because it forms biofilms in diverse habitats, including soil, rivers, sewage, and medical devices in humans (1, 2, 16). Two features are common to all of these environments: First, the presence of rough surfaces, which at the microscopic level reduce to surfaces with many corners, and second, a pressure-driven flow. The standard assay for growing biofilms in the laboratory abstracts from these realistic environments by typically using a smooth surface as a substrate, and either no flow or a pump to force nutritious medium across the biofilm at a constant flow rate (17-19). These standard assays have enabled the identification of several genes involved in biofilm develo...

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“…The standard planktonic bacterial physiology is typically exemplified by free-living single bacteria with optimal nutrition, gas exchange and agitation (typically 250 rpm) [24,25]. In contrast, the biofilm physiology has multicellular differentiation, multicellular communication, internal architecture and rudimentary fluid transport systems [26,27]. Shah et al [4] reported on the antibacterial activity of SLs in various carbohydrate-containing media against a selection of Gram-positive and Gram-negative bacteria, in our study we selected Cupriavidus necator ATCC 17699 and…”

Section: Discusionmentioning

confidence: 99%

Sophorolipid biosurfactants: Possible uses as antibacterial and antibiofilm agent

et al. 2015

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Biosurfactants are amphipathic, surface-active molecules of microbial origin which accumulate at interfaces reducing interfacial tension and leading to the formation of aggregated micellular structures in solution. Some biosurfactants have been reported to have antimicrobial properties, the ability to prevent adhesion and to disrupt biofilm formation. We investigated antimicrobial properties and biofilm disruption using sophorolipids at different

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Optically Transparent Porous Medium for Nondestructive Studies of Microbial Biofilm Architecture and Transport Dynamics

Cited by 64 publications

References 49 publications

Hydrodynamic and Chemical Factors in Clogging by Montmorillonite in Porous Media

Hydrodynamic and Chemical Factors in Clogging by Montmorillonite in Porous Media

Biofilm streamers cause catastrophic disruption of flow with consequences for environmental and medical systems

Sophorolipid biosurfactants: Possible uses as antibacterial and antibiofilm agent

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