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Screening, characterization and flocculating property of carbohydrate polymer from newly isolated Enterobacter cloacae WD7
A total of 188 carbohydrate polymer-producing bacterial strains were isolated from recycled sludge of five seafood processing plants. Among three selected isolates, identified as Enterobacter cloacae WD7, Enterobacter agglomerans WD50 and Pseudomonas alcaligenes WD22. E. cloacae WD7 generated a visc...
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Published in: | Carbohydrate polymers 2006-11, Vol.66 (3), p.289-297 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | A total of 188 carbohydrate polymer-producing bacterial strains were isolated from recycled sludge of five seafood processing plants. Among three selected isolates, identified as
Enterobacter cloacae WD7,
Enterobacter agglomerans WD50 and
Pseudomonas alcaligenes WD22.
E. cloacae WD7 generated a viscous culture broth exhibiting the highest flocculating activity and a crude polymer yield of 2.27
g/L after 3 days cultivation. Partial purification of this polymer was performed by precipitation with 95% ethanol, dialysis and freeze-drying. It was characterized as an acidic heteropolysaccharide, composed of neutral sugars (29.4%), uronic acids (14.2%) and amino sugars (0.93%). The functional group analysis by FT-IR spectroscopy showed the presence of hydroxyl, carboxyl, carbonyl and methoxyl groups. Thermal analysis by DSC showed the crystalline transition and the crystalline melting point (
T
m) at 300
°C. This polysaccharide was soluble in water and insoluble in any organic solvents tested; gelation occurred under alkaline conditions in the presence of divalent cations in which copper as CuSO
4 gave the best result. Studies on the flocculation property revealed that this polysaccharide was stable at 4–60
°C and pH 5–7. The optimal concentrations for the flocculating activity were 2
mg/L polysaccharide and 40
mM CaCl
2 which played the synergistic effect on kaolin flocculation. Moreover, this polysaccharide could flocculate the kaolin suspension over a wide range of pH (pH 2–8) and temperature (4–50
°C) tested in the presence of CaCl
2. |
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ISSN: | 0144-8617 1879-1344 |
DOI: | 10.1016/j.carbpol.2006.03.011 |