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

Dipartimento di Biologia, Difesa e Biotecnologie Agro-forestali, Università della Basilicata, Potenza, Italy.
Journal of Applied Microbiology (Impact Factor: 2.48). 02/2002; 92(2):297-306. DOI: 10.1046/j.1365-2672.2002.01487.x
Source: PubMed


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.
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 degrees 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 x 10(6) and 5 x 10(4), 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.
The fermentation conditions and some properties of an EPS produced by Strep. thermophilus, a dairy starter organism, were described.

Download full-text


Available from: Flavio Zanetti, Oct 08, 2014

Click to see the full-text of:

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

418.63 KB

See full-text
  • Source
    • "These complex polymers can also contain acetylated amino sugar moieties, as well as noncarbohydrate constituents such as phosphate, lactate, acetate and glycerol (De Vuyst & Degeest, 1999; De Vuyst et al., 2001; Ruas-Madiedo et al., 2002; Girard & Schaffer-Lequart, 2007). The composition of the bacterial EPS varies with the type of microorganism (Vaningelgem et al., 2004; Panhota et al., 2007), nutrient availability (De Vuyst & Degeest, 1999; Ricciardi et al., 2002), growth phase and environmental conditions (Fischer et al., 2003; Bahat-Samet et al., 2004). However, the mechanisms involved in the synthesis of EPS seem to be relatively conserved for Gram-negative and Gram-positive bacteria (De Vuyst et al., 2001; Jolly & Stingele, 2001; Laws et al., 2001; Sutherland, 2001; Welman & Maddox, 2003; Whitfield, 2006). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Cyanobacterial extracellular polymeric substances (EPS) are mainly composed of high-molecular-mass heteropolysaccharides, with variable composition and roles according to the microorganism and the environmental conditions. The number of constituents - both saccharidic and nonsaccharidic - and the complexity of structures give rise to speculations on how intricate their biosynthetic pathways could be, and how many genes may be involved in their production. However, little is known regarding the cyanobacterial EPS biosynthetic pathways and regulating factors. This review organizes available information on cyanobacterial EPS, including their composition, function and factors affecting their synthesis, and from the in silico analysis of available cyanobacterial genome sequences, proposes a putative mechanism for their biosynthesis.
    FEMS microbiology reviews 06/2009; 33(5):917-41. DOI:10.1111/j.1574-6976.2009.00183.x · 13.24 Impact Factor
  • Source
    • "and other industries). Most studies on EPS production have been carried out with pure cultures of pathogenic strains or of industrial interest, and although it is not possible to generalize results obtained by one species, it is known that EPS synthesis is influenced by environmental variables such as temperature, pH, oxygen, carbon source, which can be used to control the production of EPS for different purposes (Ricciardi et al. 2002; López et al. 2003; Nampoothiri et al. 2003). Also, for a reduction in production costs and the use of clean technology, agroindustrial by-products such as corn-steep liquor and molasses, may be utilized as alternative growth subtract to produce EPS (Sutherland 1996; Fusconi 2005). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Gordonia polyisoprenivorans CCT 7137 was isolated from groundwater contaminated with leachate in an old controlled landfill (São Paulo, Brazil), and cultured in GYM medium at different concentrations of sugarcane molasses (2%, 6%, and 10%). The strain growth was analyzed by monitoring the viable cell counts (c.f.u.mL−1) and optical density and EPS production was evaluated at the end of the exponential phase and 24h after it. The analysis of the viable cell counts showed that the medium that most favored bacterial growth was not the one that favored EPS production. The control medium (GYM) was the one that most favored the strain growth, at the maximum specific growth rate of 0.232h−1. Differences in bacterial growth when cultured at three different concentrations of molasses were not observed. Production of EPS, in all culture media used, began during the exponential phase and continued during the growth stationary phase. The highest total EPS production, after 24h of stationary phase, was observed in 6% molasses medium (172.86gL−1) and 10% (139.47gL−1) and the specific total EPS production was higher in 10% molasses medium (39.03×10−11gc.f.u.−1). After the exponential phase, in 2%, 6%, and 10% molasses media, a higher percentage of free exopolysaccharides (EPS) was observed, representing 88.4%, 62.4%, and 64.2% of the total, respectively. A different result was observed in pattern medium, which presented EPS made up of higher percentage of capsular EPS (66.4% of the total). This work is the first study on EPS production by G.polyisoprenivorans strain in GYM medium and in medium utilizing sugarcane molasses as the sole nutrient source and suggests its potential use for EPS production by G.polyisoprenivorans CCT 7137 aiming at application in biotechnological processes.
    World Journal of Microbiology and Biotechnology 06/2008; 24(7):937-943. DOI:10.1007/s11274-007-9570-9 · 1.78 Impact Factor
  • Source
    • "Earlier studies revealed that though EPS synthesis by thermophilic LAB occurs at an optimum pH of 4.0 (Mozzi, Oliver, Savoy de Giori, & Font de Valdez, 1995) a pH of 5.5 and temperature of 40 °C were found to be optimal for EPS production by Streptococcus thermophilus 1275 with a very low yield of 458 mg/L (Zisu & Shah, 2003). Similarly, depending on the medium composition , the quantity of EPS produced by S. thermophilus was 152 and 600 mg/L in whey medium (Ricciardi et al., 2002) and skim milk medium (Cerning et al., 1992), respectively . This is very low compared to the yield obtained in the present study. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Exopolysaccharide (EPS) producing non-ropy strain of lactic acid bacteria (LAB) was isolated from dahi, an Indian traditional fermented milk product, and on the basis of morphology, physiological and biochemical tests it was identified as Leuconostoc sp. CFR 2181. In shake flask fermentation for 72 h at 22 °C, the quantity of EPS produced by the isolate was 13.8 g/L in modified MRS broth and 25.4 g/L in EPS medium (a newly formulated simplified synthetic medium). The EPS was non-gelling and non-film forming. It was completely soluble in water and 1N sodium hydroxide solution. The purified EPS contained 84% of total carbohydrates, 11.2% of reducing sugars, 2% of moisture, 0.8% of proteins and 0.6% uronic acid. The EPS consisted mainly of glucose (91%) with minor quantities of rhamnose and arabinose (1.8% each). Gel permeation chromatography indicated considerable heterogeneity of EPS, having three fractions with molecular weights ranging from 1.0 × 104 to 1.5 × 106 Da. Enzymatic hydrolysis with pullulanase and α-amylase and NMR analysis of the EPS indicated the presence of α (1 → 6) linkages and the absence of α (1 → 4) linkages. © 2007 Elsevier Ltd. All rights reserved.
    Carbohydrate Polymers 05/2008; 72(2):300-307. DOI:10.1016/j.carbpol.2007.08.016 · 4.07 Impact Factor
Show more