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BioMed Research International
Volume 2018, Article ID 1896240, 11 pages
Research Article

Evaluation of the Efficiency of Ethanol Precipitation and Ultrafiltration on the Purification and Characteristics of Exopolysaccharides Produced by Three Lactic Acid Bacteria

1Laboratory of Microbial Ecology and Technology, LETMi-INSAT, National Institute of Applied Sciences and Technology INSAT, Carthage University, 2 Boulevard de la Terre, BP 676, 1080 Tunis, Tunisia
2Centre de Recherche sur les Macromolécules Végétales, CERMAV, CNRS, 601 rue de la Chimie, 38041 Grenoble Cedex 9, France
3National Research Center for Materials Science, Borj-Cedria Technopark, BP N°73, 8027 Soliman, Tunisia

Correspondence should be addressed to Manel Ziadi; rf.oohay@25z_lenam

Received 29 April 2018; Accepted 9 August 2018; Published 18 September 2018

Academic Editor: Taoufik Ghrairi

Copyright © 2018 Manel Ziadi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Exopolysaccharides (EPS) produced by three Lactic Acid Bacteria strains, Lactococcus lactis SLT10, Lactobacillus plantarum C7, and Leuconostoc mesenteroides B3, were isolated using two methods: ethanol precipitation (EPS-ETOH) and ultrafiltration (EPS-UF) through a 10 KDa cut-off membrane. EPS recovery by ultrafiltration was higher than ethanol precipitation for Lactococcus lactis SLT10 and Lactobacillus plantarum C7. However, it was similar with both methods for Leuconostoc mesenteroides B3. The monomer composition of the EPS fractions revealed differences in structures and molar ratios between the two studied methods. EPS isolated from Lactococcus lactis SLT10 are composed of glucose and mannose for EPS-ETOH against glucose, mannose, and rhamnose for EPS-UF. EPS extracted from Lactobacillus plantarum C7 and Leuconostoc mesenteroides B3 showed similar composition (glucose and mannose) but different molar ratios. The molecular weights of the different EPS fractions ranged from 11.6±1.83 to 62.4±2.94 kDa. Molecular weights of EPS-ETOH fractions were higher than those of EPS-UF fractions. Fourier transform infrared (FTIR) analysis revealed a similarity in the distribution of the functional groups (O-H, C-H, C=O, -COO, and C-O-C) between the EPS isolated from the three strains.