• Journal of Microbiology and Biotechnology
• /
• v.31 no.8
• /
• pp.1144-1153
• /
• 2021

A released exopolysaccharide (rEPS)-producing strain (LM187) with good acid resistance, bile salt resistance, and cholesterol-lowering properties was isolated from Sichuan paocai and identified as Leuconostoc mesenteroides subsp. mesenteroides. The purified rEPS, designated as rEPS414, had a uniform molecular weight of 7.757 × 10⁵ Da. Analysis of the monosaccharide composition revealed that the molecule was mainly composed of glucose. The Fourier transform-infrared spectrum showed that rEPS414 contained both α-type and β-type glycosidic bonds. ¹H and ¹³C nuclear magnetic resonance spectra analysis showed that the purified rEPS contained arabinose, galactose, and rhamnose, but less uronic acid. Scanning electron microscopy demonstrated that the exopolysaccharide displayed a large number of scattered, fluffy, porous cellular network flake structures. In addition, rEPS414 exhibited strong in vitro antioxidant activity. These results showed that strain LM187 and its rEPS are promising probiotics with broad prospects in industry.

• ALGAE
• /
• v.21 no.2
• /
• pp.253-259
• /
• 2006

Organic substances are released from phytoplankton cells during all phases of growth. The type and amounts of organic substance excreted and the effects of nutrient limitation are often highly species-specific. Dinoflagellate, Cochlodinium polykrikoides grown in batch culture produced an exopolysaccharide. Exopolysaccharide and intracellular polysaccharide concentrations increased as C. polykrikoides cultures progressed from exponential phase, through stationary phase, to declining phase. In the exponential phase, the concentration of exopolysaccharide was relatively low, but in the stationary phase, it showed a rapid increase which seemed to coincide with the depletion of nitrate from the medium. Of the 20 amino acids analyzed, proline dominated in the organic matter of all cultures ranging from 48.2 to 79.9 nmol L–1, and constituting the 20-90% of total amino acids, and followed by histamine varying from 0.7 to 47.5 nmol L–1. Leucine and cysteine were also abundant in the stationary phase. The release rates of exopolysaccharide and intracellualr polysaccharide were higher the end of stationary phase than in the exponential phase. Exopolysaccharide concentration per cell was more than two times higher during the end of stationary phase than that in exponential phase. C. polykrikoides produced extracellular polysaccharide at a rate of 47.04 pg cell–1 day–1.

• Journal of Microbiology and Biotechnology
• /
• v.16 no.6
• /
• pp.939-945
• /
• 2006

The physiological characteristics and function of the exopolysaccharide (EPS) produced by Lactobacillus rhamnosus ATCC 9595 were determined. The total quantity of EPS was rapidly increased to 496$\pm$20 mg/l during the exponential phase, and then maintained steadily during the stationary phase. During the exponential phase (18 h), the total EPS consisted of 61% cell-bound EPS (cb-EPS) and 39% released EPS (r-EPS), whereas the relative proportion of EPS during the stationary phase (48 h) was convered to 23% cb-EPS and 77% r-EPS. On gel permeation chromatography, cb-EPS was fractionated as a single peak of 8.6$\times10^6$ Da, whereas r-EPS was fractionated as two peaks with average molecular weights of 4.3$\times$10$^4$ and 8.6$\times10^6$ Da. Interestingly, both EPS species exhibited anticancer properties and cholera toxin-binding activities. Our results suggest that the EPS generated by L. rhamnosus ATCC 9595 might be suitable for use as a functional food or food supplement.

• KSBB Journal
• /
• v.23 no.1
• /
• pp.18-22
• /
• 2008

Various probiotic Lactobacillus spp. are known to produce exopolysaccharide (EPS) which has potential health promoting functionality. A Lactobacillus paracasei strain producing EPS was isolated from healthy human. This strain, named L. paracasei KLB58, was grown on modified MRS medium. Experiments were conducted under various growth conditions to optimize the EPS production. Our study showed that incubation temperature played an important role in EPS production. When incubation temperature was changed from $37^{\circ}C$ to $25^{\circ}C$, the increase of EPS production (28.1 mg/ml) was the highest in our experiment. The type of carbon source in the medium also affected EPS production. Galactose was the most effective for EPS production among the carbon sources examined. Using galactose, glucose, lactose and sucrose, the amount of released EPS was 38.9 mg/ml, 35.6 mg/ml, 21.76 mg/ml and 16.9 mg/ml, respectively. However, acidity in growth medium inhibited EPS productivity due to the low growth yield. When grown at pH 4, L. paracasei KLB58 could only produce EPS of 14.6 mg/ml. When the initial amounts of nitrogen and carbon sources were examined, EPS production was not significantly affected by nitrogen source while carbon source affected considerably.

• Journal of Microbiology and Biotechnology
• /
• v.21 no.11
• /
• pp.1174-1178
• /
• 2011

Exopolysaccharides (EPSs) are microbial polysaccharides that are released outside of the bacterial cell wall. There have been few studies on EPS-producing lactic acid bacteria that can enhance macrophage activity and the underlying signaling mechanism for cytokine expression. In the current study, EPS-overproducing Lactobacillus (L.) paracasei KB28 was isolated from kimchi and cultivated in conditioned media containing glucose, sucrose, and lactose. The whole bacterial cells were obtained with their EPS being attached, and the cytokine-inducing activities of these cells were investigated. Gas chromatography analysis showed the presence of glucose, galactose, mannose, xylose, arabinose, and rhamnose in EPS composition. EPS-producing L. paracasei KB28 induced the expression of tumor necrosis factor (TNF)-${\alpha}$, interleukin (IL)-6, and IL-12 in mouse macrophages. This strain also caused the degradation of $I{\kappa}B{\alpha}$ and phosphorylation of the major MAPKs: Jun N-terminal kinase (JNK), p38, and extracellular signal-regulated kinase (ERK)1/2. The use of pharmacological inhibitors showed that different signaling pathways were involved in the induction of TNF-${\alpha}$, IL-6 and IL-12 by L. paracasei KB28. Our results provide information for a better understanding of the molecular mechanisms of the immunomodulatory effect of food-derived EPS-producing lactic acid bacteria.