Production of a Novel Extracellular Polysaccharide by Lactobacillus sake 0-1 and Characterization of the Polysaccharide

Abstract

A novel exopolysaccharide (EPS) produced by Lactobacillus sake 0-1 (CBS 532.92) has been isolated and characterized. When the strain was grown on glucose, the produced EPS contained glucose and rhamnose in a molar ratio of 3:2 and the average molecular mass distribution (M m) was determined at 6 ؋ 10 6 Da. At a concentration of 1%, the 0-1 EPS had better viscosifying properties than xanthan gum when measured over a range of shear rates from 0 to 300 s ؊1 , while shear-thinning properties were comparable. Rheological data and anion-exchange chromatography suggested the presence of a negatively charged group in the EPS. Physiological parameters for optimal production of EPS were determined in batch fermentation experiments. Maximum EPS production was 1.40 g ⅐ liter ؊1 , which was obtained when L. sake 0-1 had been grown anaerobically at 20؇C and pH 5.8. When cultured at lower temperatures, the EPS production per gram of biomass increased from 600 mg at 20؇C to 700 mg at 10؇C but the growth rate in the exponential phase decreased from 0.16 to 0.03 g ⅐ liter ؊1 ⅐ h ؊1. EPS production started in the early growth phase and stopped when the culture reached the stationary phase. Growing the 0-1 strain on different energy sources such as glucose, galactose, mannose, fructose, lactose, and sucrose did not alter the composition of the EPS produced.

Screening for gum‐producing Lactic acid bacteria in Oil palm (Elaeis guineensis) and raphia palm (Raphia regalis) sap from South‐West Nigeria

“…Sucrose was first converted to glucose and glucose was completely converted into lactic acid to yield the necessary energy, enough nitrogen is necessary for the biosynthesis of essential cell components, while the cells actively produce exopolysaccharides in the presence of an appropriate carbon source (Cerning et al, 1994). Growth associated exopolymer production has been observed for several lactic acid bacteria strains (De Vuyst, Vanderveken, Van de Ven, & Degeest, 1998;Ricciardi et al, 2002;Van Den Berg et al, 1995) and other bacteria (Sunil, Amarsinh, Trishala, & Tejswini, 2013;Valepyn et al, 2012). The increase in TA B L E 3 Production of EPS in 6% sucrose broth from bacteria isolated from palm wine yields of exopolysaccharides biosynthesis obtained in this study could be attributed to the fermentation temperature and pH.…”

Mutational analysis of exopolysaccharide biosynthesis byLactobacillus sakei 0-1

“…Liquid cultures were incubated without aeration and without shaking. For enzyme assays and EPS production, strains were grown in a semi-de¢ned medium (SDM) [16].…”

“…sakei cultures were harvested by centrifugation at 12 000Ug for 30 min at 20³C. EPS was removed from bacterial cells by forcing the viscous culture broth through a 50-ml syringe [16]. Cells were washed with 50 mM Tris-HCl (pH 7.6) and stored as a pellet at 320³C until use.…”

“…Strain 0-1 produced 2 g l 3I of EPS in SDM medium at 30³C [16]. On MRS agar plates, colonies of strain 0-1 were routinely checked for ropiness, but no non-ropy colonies were found.…”

“…Lactobacillus sakei strain 0-1 (formerly L. sake 0-1, see [14]) was isolated from a naturally fermented Belgium salami sausage [15]. This strain is able to produce up to 2.5 g l 3I of a heteropolysaccharide EPS, the highest value reported for a lactic acid bacterium [16]. The repeating unit of this EPS contains glucose, rhamnose, acetate and phosphoglycerol in a ratio of 3:2:0.85:1 [9] (Fig.…”