Gels

Morris, Victor J.

doi:10.1002/9780470995792.ch6

Cited by 7 publications

(4 citation statements)

References 117 publications

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“…Thus, the agarose network formation is less restricted compared to the formation when xanthan is added. Such swollen networks were already observed for other mixtures of a gelling agent with nongelling hydrocolloids . Effectively, the flexible alginate molecules provide larger entropy, which yields a larger modulus.…”

Section: Results and Discussionsupporting

confidence: 59%

Influence of Nongelling Hydrocolloids on the Gelation of Agarose

et al. 2013

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The combination of different gelling and nongelling hydrocolloids is known to yield complex systems with a wide range of mechanical properties. Here, the influence of the nongelling hydrocolloids sodium-alginate and xanthan on the gelation of agarose is investigated. The two polyelectrolytes differ significantly in their flexibility, leading to opposing effects on the thermomechanical properties of the resulting composite gels. The network structure of the agarose as well as viscoelasticity, gelling temperature, and thermal stability of the gels are altered. These properties are investigated by strain and temperature dependent oscillatory rheological measurements as well as confocal laser scanning microscopy. A phenomenological model to describe the network formation of agarose in the presence of alginate or xanthan respectively is presented.

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Section: Results and Discussionsupporting

confidence: 59%

Influence of Nongelling Hydrocolloids on the Gelation of Agarose

et al. 2013

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“…aggregates was associated with these BMM significantly ( P < 0.05). BMM has been widely confirmed to be involved in bacterial aggregation previously. − Indeed, BMMs were previously described as a backbone with a structural function in bioaggregates, causing the network to swell and pores to open up for nutrient diffusion into and out of the aggregates . Indeed, one of the prerequisites of microalgal aggregation appears to be BMM production, which is similar to bacterial aggregation.…”

Section: Resultsmentioning

confidence: 92%

Responses of the MicroalgaChlorophytasp. to Bacterial Quorum Sensing Molecules (N-Acylhomoserine Lactones): Aromatic Protein-Induced Self-Aggregation

Zhou

Zhang

et al. 2017

Environ. Sci. Technol.

112

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Bacteria and microalgae often coexist during the recycling of microalgal bioresources in wastewater treatment processes. Although the bacteria may compete with the microalgae for nutrients, they could also facilitate microalgal harvesting by forming algal-bacterial aggregates. However, very little is known about interspecies interactions between bacteria and microalgae. In this study, we investigated the responses of a model microalga, Chlorophyta sp., to the typical quorum sensing (QS) molecules N-acylhomoserine lactones (AHLs) extracted from activated sludge bacteria. Chlorophyta sp. self-aggregated in 200 μm bioflocs by secreting 460-1000 kDa aromatic proteins upon interacting with AHLs, and the settling efficiency of Chlorophyta sp. reached as high as 41%. However, Chlorophyta sp. cells were essentially in a free suspension in the absence of AHLs. Fluorescence intensity of the aromatic proteins had significant (P < 0.05) relationship with the Chlorophyta sp. settleability, and showed a positive correlation, indicating that aromatic proteins helped aggregate microalga. Transcriptome results further revealed up-regulation of synthesis pathways for aromatic proteins from tyrosine and phenylalanine that was assisted by anthranilate accumulation. To the best of our knowledge, this is the first study to confirm that eukaryotic microorganisms can sense and respond to prokaryotic QS molecules.

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“…In contrast, the low- and medium-MW fraction may have a nonstructural function, fixed to the gel as an energy or nutrition source or to facilitate cell−cell communications . It may also be hydrophilic “filler”, residing in the polysaccharide gel to assimilate water, swell the network, and open up pores for nutrient diffusion in and out of the granules .…”

Section: Discussionmentioning

confidence: 99%

Purification and Conformational Analysis of a Key Exopolysaccharide Component of Mixed Culture Aerobic Sludge Granules

Seviour

Donose

Pijuan

et al. 2010

Environ. Sci. Technol.

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The application of aerobic sludge granules in wastewater treatment could increase the intensity of wastewater treatment processes because of their greater density and size relative to conventional sludge flocs. It has been suggested that granules are distinguished from flocs by gel forming exopolysaccharides. In this study, evidence is presented linking a specific exopolysaccharide component with granule extracellular polymeric substance (EPS) gelation. Granular EPS comprised three components: high-molecular-weight (MW) exopolysaccharide, medium-MW proteins and glycosides, and low-MW proteins and glycosides. The high-MW fraction was separated by fractional precipitation and preparatory-scale gel permeation chromatography (GPC). The MW profile of this fraction appears to be exclusively attributable to high-MW polysaccharide. The exopolysaccharide exists as a gel at normal wastewater treatment operating pH (i.e., 6.0-8.5), whereas the low/medium-MW material does not. Conformational analysis by atomic force microscopy (AFM) of the dried material showed that the polysaccharide forms pearl-necklace-like, intramolecularly condensed structures when dissolved in Milli-Q water and partially relaxed helical aggregates when in alkali solution. Consequently, the gel-forming property of EPS in the aerobic sludge granules tested is probably associated with high-MW polysaccharide components.

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Gels

Cited by 7 publications

References 117 publications

Influence of Nongelling Hydrocolloids on the Gelation of Agarose

Influence of Nongelling Hydrocolloids on the Gelation of Agarose

Responses of the MicroalgaChlorophytasp. to Bacterial Quorum Sensing Molecules (N-Acylhomoserine Lactones): Aromatic Protein-Induced Self-Aggregation

Purification and Conformational Analysis of a Key Exopolysaccharide Component of Mixed Culture Aerobic Sludge Granules

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