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Exopolysaccharide production by Streptococcus thermophilus SY: production and preliminary characterization of the polymer

Ricciardi, Annamaria and Parente, Eugenio and Crudele, Maria Antonietta and Zanetti, Federica and Scolari, Gianluigi and Mannazzu, Ilaria Maria (2002) Exopolysaccharide production by Streptococcus thermophilus SY: production and preliminary characterization of the polymer. Journal of Applied Microbiology, Vol. 92 (2), p. 297-306. eISSN 1365-2672. Article.

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DOI: 10.1046/j.1365-2672.2002.01487.x

Abstract

Aims: To evaluate the effect of yeast extract (YE) concentration, temperature and pH on growth and exopolysaccharide (EPS) production in a whey-based medium by Streptococcus thermophilus SY and to characterize the partially purified EPS.
Methods and Results: Factorial experiments and empirical model building were used to optimize fermentation conditions and the chemical composition, average molecular weight (MW) and rheological properties of aqueous dispersions of the EPS were determined. Exopolysaccharide production was growth associated and was higher (152 mg l–1) at pH 6•4 and 36°C with 4 g l–1 YE. High performance size exclusion chromatography of the partially purified EPS showed two peaks, with a weight average MW of 2 × 106 and 5 × 104, respectively. The EPS was a heteropolysaccharide, with a glucose : galactose : rhamnose ratio of 2 : 4•5 : 1. Its water dispersions had a pseudoplastic behaviour and showed a higher viscosity of xanthan solutions.
Significance and Impact of the Study: The fermentation conditions and some properties of an EPS produced by Strep. thermophilus, a dairy starter organism, were described.

Item Type:Article
ID Code:3820
Status:Published
Refereed:Yes
Uncontrolled Keywords:Streptococcus thermophilus, yeast extract concentration, exopolysaccharide production
Subjects:Area 07 - Scienze agrarie e veterinarie > AGR/16 Microbiologia agraria
Divisions:001 Università di Sassari > 01 Dipartimenti > Scienze ambientali agrarie e biotecnologie agro-alimentari
Publisher:The Society for Applied Microbiology
eISSN:1365-2672
Deposited On:04 May 2010 10:27

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