title: Guluronic acid content as a factor affecting turbidity removal potential of alginate.
abstract: Alginates are natural polymers composed of mannuronic and guluronic acid residues. They are currently extracted from brown algae; however, alginate can also be synthesized by some species of Azotobacter and Pseudomonas. Alginates with different proportion of mannuronic and guluronic acids are known to have different characteristics and form gels at different extents in the presence of calcium ions. The aim of this work was to investigate the usefulness of alginate as a non-toxic coagulant used in purification of drinking water. This study utilized alginates from Azotobacter vinelandii having different guluronic acid levels. These were obtained partly by changing the cultivation parameters, partly by epimerizing a purified alginate sample in vitro using the A. vinelandii mannuronan C-5 epimerase AlgE1. The different alginates were then used for coagulation together with calcium. The results showed that turbidity removal capability was dependent on the content of guluronic acid residues. For the best performing samples, the turbidity decreased from 10 NTU to 1 NTU by the use of only 2 mg/L of alginate and 1.5 mM of calcium chloride.
authors: Department of Environmental Engineering, Middle East Technical University, 06800, Ankara, Turkey.|Department of Environmental Engineering, Akdeniz University, 07058, Antalya, Turkey.
authors: Çiğdem
authors: Ç
authors: Kıvılcımdan Moral
authors: Department of Biotechnology, Norwegian University of Science and Technology, Trondheim, Norway.
authors: Helga
authors: H
authors: Ertesvåg
authors: Department of Environmental Engineering, Middle East Technical University, 06800, Ankara, Turkey. dsanin@metu.edu.tr.
authors: F Dilek
authors: FD
authors: Sanin
mesh_terms: D000464:Alginates / Q000737:chemistry; D000595:Amino Acid Sequence; D016948:Azotobacter vinelandii / Q000737:chemistry; D002238:Carbohydrate Epimerases / Q000032:analysis; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000032:analysis*; D018508:Water Purification
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; C007896:guluronic acid; D020723:Glucuronic Acid; D002238:Carbohydrate Epimerases; C086519:mannuronan c-5-epimerase
keywords: Alginate; Azotobacter vinelandii; Coagulation; Guluronic acid blocks; Turbidity removal