Purification and conformational analysis of a key exopolysaccharide component of mixed culture aerobic sludge granules

Thomas Seviour, Bogdan C. Donose, Maite Pijuan, Zhiguo Yuan*

*Corresponding author for this work

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

87 Citations (Scopus)

Abstract

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. © 2010 American Chemical Society.
Original languageEnglish
Pages (from-to)4729-4734
JournalEnvironmental Science and Technology
Volume44
Issue number12
DOIs
Publication statusPublished - 15 Jun 2010
Externally publishedYes

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