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Sinorhizobium meliloti 1021 Exopolysaccharide as a Flocculant Improving Chromium(III) Oxide Removal from Aqueous Solutions.

Szewczuk-Karpisz K, Wiśniewska M, Pac M, Choma A, Komaniecka I - Water Air Soil Pollut (2014)

Bottom Line: Moreover, the stability of Cr2O3 suspension in the absence and presence of S. meliloti 1021 EPS was estimated.The pooled analysis of all obtained results showed that EPS causes chromium(III) oxide suspension destabilization in the whole examined pH range.The largest change in the system stability before and after the polymer addition was observed at pH 9.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiochemistry and Colloid Chemistry, Faculty of Chemistry, Maria Curie Sklodowska University, M. Curie Sklodowska Sq. 3, 20-031 Lublin, Poland.

ABSTRACT
Chromium(III) oxide is an amphoteric, dark green solid. This most stable dye is widely used in construction and ceramic industries as well as in painting. In this study, the attempt is made to determine flocculating properties of exopolysaccharide (EPS) synthesized by the bacteria Sinorhizobium meliloti 1021, which would increase the efficiency of chromium(III) oxide removal from sewages and wastewaters. The conditions under which EPS is the most effective destabilizing component of chromium(III) oxide suspension have been determined too. In order to characterize the structure of electric double layer formed at the solid/supporting electrolyte (EPS) solution interface, electrokinetic potential measurements and potentiometric titration were performed. The EPS amount adsorbed on the chromium(III) oxide surface as a solution pH function was also measured. Moreover, the stability of Cr2O3 suspension in the absence and presence of S. meliloti 1021 EPS was estimated. The pooled analysis of all obtained results showed that EPS causes chromium(III) oxide suspension destabilization in the whole examined pH range. The largest change in the system stability before and after the polymer addition was observed at pH 9. It is probable that under these conditions bridging flocculation occurs in the examined system.

No MeSH data available.


Related in: MedlinePlus

Structure of the Sinorhizobium meliloti 1021 exopolysaccharide monomer
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Related In: Results  -  Collection


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Fig1: Structure of the Sinorhizobium meliloti 1021 exopolysaccharide monomer

Mentions: Exopolysaccharides (EPS) are macromolecular compounds synthesized in large quantities by all soil bacteria belonging to the Rhizobiaceae family. They play a key role in the establishment of symbiosis between bacteria and legume plants (Janczarek et al. 1999). In this paper there is used EPS synthesized by Sinorhizobium meliloti 1021. These bacteria can produce two types of EPS, defined as EPS I and EPS II. The first type (EPS I) is succinoglycan, composed of octasaccharide subunits containing seven glucose and one galactose molecules joined by β-1, 3, β-1, 4 and β-1, 6 glycosidic bonds (Skorupska et al. 2006). Succinoglycan has a polysaccharide skeleton modified by acetyl, pyruvyl and succinyl substituents (Reinhold et al. 1994). The structure of octasaccharide S. meliloti 1021 EPS unit is shown in Fig. 1 (Simsek et al. 2007). EPS II is galactoglucan composed of disaccharide units containing acetylated glucose and galactose substituted by the puryvic acid residue linked by β-1, 3 and α-1, 3 glycosidic bonds. This EPS is synthesized either in the phosphorus compounds poor medium or due to mutation of specific regulatory genes (Bahlawane et al. 2008; Pellock et al. 2002). Both EPS types are produced in two fractions: high molecular weight (HMW) and low molecular weight (LMW). The HMW fraction includes EPS macromolecules made up of several hundred/a few thousand subunits. Their weight is in the range 106–107 Da (Gharzouli et al. 2013). The LMW fraction is composed of monomers, dimers and trimers in the case of EPS I or oligomers containing 15–20 units in the case of EPS II (Wang et al. 1999).Fig. 1


Sinorhizobium meliloti 1021 Exopolysaccharide as a Flocculant Improving Chromium(III) Oxide Removal from Aqueous Solutions.

Szewczuk-Karpisz K, Wiśniewska M, Pac M, Choma A, Komaniecka I - Water Air Soil Pollut (2014)

Structure of the Sinorhizobium meliloti 1021 exopolysaccharide monomer
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4127006&req=5

Fig1: Structure of the Sinorhizobium meliloti 1021 exopolysaccharide monomer
Mentions: Exopolysaccharides (EPS) are macromolecular compounds synthesized in large quantities by all soil bacteria belonging to the Rhizobiaceae family. They play a key role in the establishment of symbiosis between bacteria and legume plants (Janczarek et al. 1999). In this paper there is used EPS synthesized by Sinorhizobium meliloti 1021. These bacteria can produce two types of EPS, defined as EPS I and EPS II. The first type (EPS I) is succinoglycan, composed of octasaccharide subunits containing seven glucose and one galactose molecules joined by β-1, 3, β-1, 4 and β-1, 6 glycosidic bonds (Skorupska et al. 2006). Succinoglycan has a polysaccharide skeleton modified by acetyl, pyruvyl and succinyl substituents (Reinhold et al. 1994). The structure of octasaccharide S. meliloti 1021 EPS unit is shown in Fig. 1 (Simsek et al. 2007). EPS II is galactoglucan composed of disaccharide units containing acetylated glucose and galactose substituted by the puryvic acid residue linked by β-1, 3 and α-1, 3 glycosidic bonds. This EPS is synthesized either in the phosphorus compounds poor medium or due to mutation of specific regulatory genes (Bahlawane et al. 2008; Pellock et al. 2002). Both EPS types are produced in two fractions: high molecular weight (HMW) and low molecular weight (LMW). The HMW fraction includes EPS macromolecules made up of several hundred/a few thousand subunits. Their weight is in the range 106–107 Da (Gharzouli et al. 2013). The LMW fraction is composed of monomers, dimers and trimers in the case of EPS I or oligomers containing 15–20 units in the case of EPS II (Wang et al. 1999).Fig. 1

Bottom Line: Moreover, the stability of Cr2O3 suspension in the absence and presence of S. meliloti 1021 EPS was estimated.The pooled analysis of all obtained results showed that EPS causes chromium(III) oxide suspension destabilization in the whole examined pH range.The largest change in the system stability before and after the polymer addition was observed at pH 9.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiochemistry and Colloid Chemistry, Faculty of Chemistry, Maria Curie Sklodowska University, M. Curie Sklodowska Sq. 3, 20-031 Lublin, Poland.

ABSTRACT
Chromium(III) oxide is an amphoteric, dark green solid. This most stable dye is widely used in construction and ceramic industries as well as in painting. In this study, the attempt is made to determine flocculating properties of exopolysaccharide (EPS) synthesized by the bacteria Sinorhizobium meliloti 1021, which would increase the efficiency of chromium(III) oxide removal from sewages and wastewaters. The conditions under which EPS is the most effective destabilizing component of chromium(III) oxide suspension have been determined too. In order to characterize the structure of electric double layer formed at the solid/supporting electrolyte (EPS) solution interface, electrokinetic potential measurements and potentiometric titration were performed. The EPS amount adsorbed on the chromium(III) oxide surface as a solution pH function was also measured. Moreover, the stability of Cr2O3 suspension in the absence and presence of S. meliloti 1021 EPS was estimated. The pooled analysis of all obtained results showed that EPS causes chromium(III) oxide suspension destabilization in the whole examined pH range. The largest change in the system stability before and after the polymer addition was observed at pH 9. It is probable that under these conditions bridging flocculation occurs in the examined system.

No MeSH data available.


Related in: MedlinePlus