• Microbiology and Biotechnology Letters
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• v.21 no.5
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• pp.478-485
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• 1993

The strain which produced highly viscous exopolysaccharides (EPS) in liquid culture was selected from soil. The strain was supposed to Bacillus sp. from the results of mophological, biochemical and physiological tests. The medium composition for EPS production was trypton 0.75%, sucrose 4%, CaCO3 0.01%, Winogradsky's nitrogen free mineral medium 5ml/l and pH 7.0. In 2-l jar fernenter, the viscosity of culture broth after 120-hr cultivation time was very high (60, 000 cps) and the amount of EPS was 6.2g/l.

• Journal of Microbiology and Biotechnology
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• v.15 no.6
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• pp.1250-1257
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• 2005

Two groups of exopolysaccharides (designated as Fr-I EPS and Fr-II EPS) were isolated from the culture filtrate of new fungal strain Trichoderma erinaceum DG-312 by Sepharose CL-6B chromatography. The structures of the exopolysaccharides were investigated using gas chromatography (GC), Fourier transform-infrared (FT-IR) spectroscopy, GCMS analysis, and NMR. GC analysis indicated that Fr-I EPS was composed of mainly mannose ($78.9\%$) and galactose ($21.1\%$), whereas Fr-II EPS contained mannose ($68.4\%$), galactose ($26.2\%$), and glucose ($5.4\%$). In the anomeric region ($950-700cm_{-1}$) of the FT-IR spectrum, both EPSs exhibited obvious characteristic absorption of $810\;cm_{-1}$, indicating the existence of mannose. The spectra of $\alpha-and\;\beta$-configurations were assigned at 880 and $914\;cm_{-1}$, respectively. The results of GC-MS analyses confirmed that both EPSs were complex heteropolysaccharides with a ($1{\rightarrow}3$)-linked mannan backbone. The C-1 region that appeared in the $^{13}C-NMR$ spectra of these EPSs indicated a typical anomeric carbon signal. The Fr-I EPS showed two anomeric carbon signals at 102.6 and 99.6 ppm, whereas the Fr-II EPS displayed four anomeric carbon signals at 102.5, 99.6, 98.5, and 94.3 ppm. The molecular characteristics of the EPSs were further investigated using a size exclusion chromatography/multi-angle laser light scattering (SEC/MALLS) system. The SEC/MALLS system revealed that the average molar masses of the EPSs were $6.592{\times}10^{4}$ (Fr-I EPS) and $1.920{\times}10^{4}$ (Fr-II EPS) g/mol, and the molecular conformation of both EPSs in aqueous solution was random coils.

• KSBB Journal
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• v.26 no.1
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• pp.33-40
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• 2011

Anti-diabetic effect of the exopolysaccharides (EPS) produced from submerged mycelial culture of Cordyceps sinensis (Cs) was studiedin a type II diabetic animal model (C57BL/6J ob/ob). This study was designed to determine whether Cs-EPS improves clinical symptoms of type II diabetes in ob/ob mice. After Cs-EPS treatment at doses of 200 mg/kg body weight, the fasting blood glucose levels decreased by 47% after 7 weeks compared with those of the control mice. According to the oral glucose tolerance test, the glucose levels recovered its baseline after 120 min in Cs-EPS-treated mice, although the blood glucose levels increased significantly after 30 min. On the other hand, the control group (not-treated) did not recovered its initial level of glucose after 120 min. Furthermore, food intake, body weight, total plasma cholesterol and triglyceride concentrations in ob/ob mice treated with Cs-EPS were significantly decreased, compared with those in control ob/ob mice. Cs-EPS treatment increased significantly the plasma insulin level and the expression of leptin mRNA in adipose tissue of Cs-EPS-treated ob/ob mice. From these results, it is demonstrated that Cs-EPS could be effective for regulating normal blood glucose levels by increasing the amounts of plasma insulin and leptin expression in ob/ob mice, indicating that this compound could be a candidate material as a dietary supplement to control hyperglycemia in patients suffering from type II diabetes.

• Microbiology and Biotechnology Letters
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• v.51 no.2
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• pp.157-166
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• 2023

Three lactic acid bacteria (LAB) producing exopolysaccharides (EPSs) were isolated from Pa (green onion)-kimchi, and identified as Weissella confusa (SKP 173), Weissella cibaria (SKP 182), and Leuconostoc citreum (SKP 281), respectively by 16S rRNA gene sequencing. The yields of EPS were 21.27, 18.53, and 15.4 g/l for EPS from SKP 173, 182, and 281, respectively when grown in MRS broth containing sucrose (5%, w/v). Total sugar contents were 64.39, 62.84, and 65.16% (w/w) for EPS from SKP 173, 182, and 281, respectively while the protein contents were 0.33, 0.31, and 0.25% (w/w), respectively. EPSs from W. confusa SKP 173 and W. cibaria SKP 182 contained glucose only but EPS from L. citreum SKP 281 contained glucose and glucitol. Viscosities of the 2% (w/w) freeze-dried EPS solution were 9.60, 8.00, and 8.20 centipoise (cP) for EPS from SKP 173, 182, and 281, respectively. Viscosities of culture grown in MRS broth with 5% sucrose (no glucose) were 92.98, 57.19, and 18.8 cP, respectively. The average molecular weights of EPSs were larger than 2 × 10⁷ Da. Fourier transform infrared spectroscopy (FT-IR) analyses of EPSs showed typical carbohydrate peaks, suggesting that the EPSs consisted of pyranose saccharides with α-(1,6) and α-(1,3) glycosidic linkages. L. citreim SKP 281 was used as the starter for yogurt fermentation, and EPS production was confirmed.

• Journal of Microbiology and Biotechnology
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• v.18 no.6
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• pp.1095-1100
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• 2008

The role of exopolysaccharides (EPSs) from a plant growth-promoting rhizobacterium, Burkholderia gladioli IN26, on elicitation of induced systemic resistance was investigated. A purified EPS induced expression of PR-1a::GUS on tobacco and elicited induced resistance against Colletotrichum orbiculare on cucumber. The maximum level of disease protection was noted when seeds were soaked in 200 ppm of the EPS. Our results indicate that EPS from specific rhizobacteria can elicit induced resistance and suggest that bacterial EPS might be a useful elicitor of resistance under field conditions.

• Journal of Microbiology and Biotechnology
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• v.34 no.6
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• pp.1239-1248
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• 2024

Peatlands are marginal agricultural lands due to highly acidic soil conditions and poor drainage systems. Drought stress is a big problem in peatlands as it can affect plants through poor root development, so technological innovations are needed to increase the productivity and sustainability of upland rice on peatlands. Rhizobacteria can overcome the effects of drought stress by altering root morphology, regulating stress-responsive genes, and producing exopolysaccharides and indole acetic acid (IAA). This study aimed to determine the ability of rhizobacteria in upland rice to produce exopolysaccharides and IAA, identify potential isolates using molecular markers, and prove the effect of rhizobacteria on viability and vigor index in upland rice. Rhizobacterial isolates were grown on yeast extract mannitol broth (YEMB) medium for exopolysaccharides production testing and Nutrient Broth (NB)+L-tryptophan medium for IAA production testing. The selected isolates identify using sequence 16S rRNA. The variables observed in testing the effect of rhizobacteria were germination ability, vigour index, and growth uniformity. EPS-1 isolate is the best production of exopolysaccharides (41.6 mg/ml) and IAA (60.83 ppm). The isolate EPS-1 was identified as Klebsiella variicola using 16S rRNA sequencing and phylogenetic analysis. The isolate EPS-1 can increase the viability and vigor of upland rice seeds. K. variicola is more adaptive and has several functional properties that can be developed as a potential bioagent or biofertilizer to improve soil nutrition, moisture and enhance plant growth. The use of rhizobacteria can reduce dependence on the use of synthetic materials with sustainable agriculture.

• Journal of Microbiology and Biotechnology
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• v.14 no.5
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• pp.944-951
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• 2004

The influences of inoculum size, pH, and medium composition on mycelial growth and exopolysaccharides (EPS) production were investigated in shake flasks and in a bioreactor. The optimum inoculum size for both mycelial growth and EPS production was identified to be 10% (v/v) in shake flask cultures. The optimal initial pH for mycelial growth and EPS production in shake flask cultures were found to be 5.0 and 7.0, respectively. However, the optimal pH was 5.0 for both mycelial growth and EPS production in bioreactor cultures where the pH was regulated. The optimal mass ratio of the two major carbon sources, glucose to dextrin, was 1:4. The optimal mass ratio of the two major nitrogen sources, yeast extract to soy tone peptone, was 2:1. When 500 mg $1^{-1}$ of $MnSO_4-5H_2O$ was added to the bioreactor culture, both mycelial growth and EPS production were enhanced by approximately 10%. Under the optimized conditions, a mycelial biomass of 9.85 g $1^{-1}$ and an EPS concentration of 4.92 g $1^{-1}$ were obtained in 4 days.

• Journal of Microbiology
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• v.44 no.2
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• pp.233-242
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• 2006

The objectives of this study were to optimize submerged culture conditions of a new fungal isolate, Ganorderma resinaceum, and to enhance the production of bioactive mycelial biomass and exopolysaccharides (EPS) by fed-batch culture. The maximum mycelial growth and EPS production in batch culture were achieved in a medium containing 10 g/l glucose, 8 g/l soy peptone, and 5 mM $MnCl_2$ at an initial pH 6.0 and temperature $31^{\circ}C$. After optimization of culture medium and environmental conditions in batch cultures, a fed-batch culture strategy was employed to enhance production of mycelial biomass and EPS. Five different EPS with molecular weights ranging from 53,000 to 5,257,000 g/mole were obtained from either top or bottom fractions of ethanol precipitate of culture filtrate. A fed-batch culture of G. resinaceum led to enhanced production of both mycelial biomass and EPS. The maximum concentrations of mycelial biomass (42.2 g/l) and EPS (4.6 g/l) were obtained when 50 g/l of glucose was fed at day 6 into an initial 10 g/l of glucose medium. It may be worth attempting with other mushroom fermentation processes for enhanced production of mushroom polysaccharides, particularly those with industrial potential.

• Journal of Microbiology and Biotechnology
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• v.18 no.3
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• pp.560-567
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• 2008

An efficient method to produce water-soluble polysaccharides from Lentinus lepideus is described. The productivity of both endopolysaccharides (PPS) and exopolysaccharides (EPS) was compared under various culture conditions. The effect of treating their own PPS and EPS on immune cytokine production was also studied in relation to culture factors. High yield production of EPS required a moderate culture temperature $(25^{\circ}C)$ as well as long culture period (16-20 days). In contrast, PPS production required a high culture temperature $(30^{\circ}C)$ and short culture period (8 days). Most of the carbon sources did not affect polysaccharides and mycelial production except for sucrose. Immune cytokine levels in the EPS treatment varied among carbon sources or culture periods. PPS did not appear to affect much on the production of cytokines, regardless of the culturing factors, except for the culture period. These results suggest that the optimal culture conditions for L. lepideus vary according to culture purposes, and different culture conditions should be used for different targets including mycelial biomass, EPS, and PPS. Whereas the immunomodulating activitiy of EPS appeared to be affected by culture conditions in L. lepideus, that of PPS did not.

• Journal of Microbiology and Biotechnology
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• v.31 no.8
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• pp.1045-1059
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• 2021

Various abiotic stressors like drought, salinity, temperature, and heavy metals are major environmental stresses that affect agricultural productivity and crop yields all over the world. Continuous changes in climatic conditions put selective pressure on the microbial ecosystem to produce exopolysaccharides. Apart from soil aggregation, exopolysaccharide (EPS) production also helps in increasing water permeability, nutrient uptake by roots, soil stability, soil fertility, plant biomass, chlorophyll content, root and shoot length, and surface area of leaves while also helping maintain metabolic and physiological activities during drought stress. EPS-producing microbes can impart salt tolerance to plants by binding to sodium ions in the soil and preventing these ions from reaching the stem, thereby decreasing sodium absorption from the soil and increasing nutrient uptake by the roots. Biofilm formation in high-salinity soils increases cell viability, enhances soil fertility, and promotes plant growth and development. The third environmental stressor is presence of heavy metals in the soil due to improper industrial waste disposal practices that are toxic for plants. EPS production by soil bacteria can result in the biomineralization of metal ions, thereby imparting metal stress tolerance to plants. Finally, high temperatures can also affect agricultural productivity by decreasing plant metabolism, seedling growth, and seed germination. The present review discusses the role of exopolysaccharide-producing plant growth-promoting bacteria in modulating plant growth and development in plants and alleviating extreme abiotic stress condition. The review suggests exploring the potential of EPS-producing bacteria for multiple abiotic stress management strategies.