• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.5
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• pp.749-755
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• 2014

Exopolysaccharides (EPSs) have been widely used in the food industry as viscofying, stabilizing, and emulsifying agents as well as in the pharmaceutical industry for their immunomodulatory, anti-tumor, and anti-inflammatory effects. A total of 458 lactic acid bacteria (LAB) strains isolated from several kinds of soybean pastes were screened for the production of homo-EPS (HoPS). LAB isolates were primarily screened using thin layer chromatography (TLC) and further screened polymerase chain reaction (PCR) targeting genes involved in HoPS production. Six LAB isolates producing high amounts of HoPS were identified by TLC. Among these isolates, glucansucrase gene was amplified in two strains (JSA57, JSB22), whereas the fructansucrase gene was detected in three strains (JSA57, JSB22, JSB66). After isolating the strains, their morphological characteristics and 16S rDNA sequences were determined. Six species were identified as L. alimentarius HSB15, L. plantarum JSA22, L. pentosus JSA57, L. brevis JSB22, L. alimentarius JSB66, and L. parabrevis JSB89. To evaluate the potential probiotic properties of these LAB, their survival rates against a simulated intestinal environment were determined. After 2 hr of incubation in artificial gastric juice, survival rates of JSA57, JSB90, JSB22, and JSB66 were all greater than 50%. After 2 hr of incubation in bile juice, viable cell count of JSB22 was similar with initial vial cell counts. Growth of the six LAB was screened in arabino-oligosaccharide (AOS)-containing MRS broth. Results showed that growth of the isolates selectively increased after culture in AOS-containing media. Strain JSB22 (6 hr), JSB66 (6 hr), HSB15 (20 hr), and JSA22 (29 hr) showed maximum growth rate. Especially, JSB22 showed the highest growth rate. These results suggest that EPS-producing LAB isolated from Deonjang could be applied as synbiotics.

• KSBB Journal
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• v.24 no.3
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• pp.303-311
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• 2009

A scaling up study for the exopolysaccharide (EPS) production by submerged culture of Ganoderma lucidum was carried out in jar fermenter systems (2.6, 20 and 75 L) under bi-staged pH process. Profiles of dissolved oxygen (DO) and volumetric coefficient of oxygen transfer ($k_La$) as a function of operating variables (agitation speed and aeration rate) was investigated, and a correlation between $k_La$ and operating variables was analysed statistically. Under bi-staged pH process, no limitation of DO was observed at agitation speeds tested in the range of 200 and 600 rpm, and the highest EPS production was obtained at the level of DO of $40{\sim}80%$. From the regression analysis, the relation between $k_La$, gas velocity (Vs), stirrer speed (N) and impeller diameter (Di) could be expressed as : $$k_La=0.555{\times}Vs^{0.42}{\times}(N^3{\times}Di^2)^{0.33}\;(R^2=0.925,\;p<0.05)$$ It was found that under 2.6 L jar fermenter, the optimum agitation speed and aeration rate was 400 rpm and 1 vvm, respectively, obtaining the EPS production of 15.43 g/L. Under the submerged cultivation of G. lucidum in jar fermenters of $2.6{\sim}75\;L$, the similar EPS yields at each fermenter were achieved during scaling up based on $k_La$, and $k_La$ value for maximum EPS production was $85.4{\pm}26.70\;h^{-1}$.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.137-140
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• 2000

Marine microorganism strain 96CJ10356 produced exopolysaccharides, designated as EPS-R. To optimize culture conditions for the production of EPS-R, carbon, nitrogen, mineral salt, temperature, and pH were examined. STN medium was suggested as follow; sucrose 20, tryptone 10, NaCl 10, $MgSO_4$ 5, $CaCl_2$ 1, $KH_2PO_4$ 0.0076, $K_2HPO_4$ 0.0083, $FeCl_2$ 0.005, $MnCl_2$ 0.001, $NaMoO_4$ 0.001, $ZnCl_2$ 0.001 (g/1) and pH 7.0 About 9.23 g/l of EPS-R was obtained from the STN medium after cultivation for 120 h at $25^{\circ}C$ in 5-liter jar fermentor with an aeration rate of 0.17 vvm. Apparent viscosity and flocculation activity of the culture broth were increased with the production of the EPS-R and the maximal values were reached to 415 cp and 1400 units/ml against 0.5 % activated carbon, respectively.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.452-459
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• 2003

In previous study, we have isolated Lactobacillus spp. from healthy human vagina and examined various characteristics such as antimicrobial substance production and exopolysaccharide (EPS) production. It is known that an EPS is an important factor of Lactobacillus spp. to adhere to epithelial cell. We have selected L. paracasei KLB58 having high antimicrobial activity and EPS production. In this study, we performed NTG (1-Methyl-3-nitro-1-nitrosoguanidine) mutagenesis to isolate an EPS deficienct mutant of KLB58 showing high cell surface hydrophobicity (CSll) compared to wild type strain. By monitoring the kinetics of the partition with hexadecane the EPS mutant was found to be far more hydrophobic than the wild type strain ; the CSH of the EPS mutant was 0.5-fold higher than the wild type strain.

• Journal of Microbiology and Biotechnology
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• v.26 no.3
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• pp.452-460
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• 2016

Acid stress can affect the viability of probiotics, especially Bifidobacterium. This study aimed to improve the acid tolerance of Bifidobacterium longum BBMN68 using adaptive evolution. The stress response, and genomic differences of the parental strain and the variant strain were compared by acid stress. The highest acid-resistant mutant strain (BBMN68m) was isolated from more than 100 asexual lines, which were adaptive to the acid stress for 10^th, 20^th, 30^th, 40^th, and 50^th repeats, respectively. The variant strain showed a significant increase in acid tolerance under conditions of pH 2.5 for 2 h (from 7.92 to 4.44 log CFU/ml) compared with the wild-type strain (WT, from 7.87 to 0 log CFU/ml). The surface of the variant strain was also smoother. Comparative whole-genome analysis showed that the galactosyl transferase D gene (cpsD, bbmn68_1012), a key gene involved in exopolysaccharide (EPS) synthesis, was altered by two nucleotides in the mutant, causing alteration in amino acids, pI (from 8.94 to 9.19), and predicted protein structure. Meanwhile, cpsD expression and EPS production were also reduced in the variant strain (p < 0.05) compared with WT, and the exogenous WT-EPS in the variant strain reduced its acid-resistant ability. These results suggested EPS was related to acid responses of BBMN68.

• Journal of Microbiology and Biotechnology
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• v.8 no.4
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• pp.341-346
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• 1998

Optimization for the production of Pest an was followed by the Plackett-Burman Design, using modified Czapek-dox medium as the starting point. At the flask level, $K_2HPO_4$, $MgSO_4{\cdot}7H_2O$, and aeration variables positively affected the Pestan production, DCW (dry cell weight), apparent viscosity, and flocculating activity response. KCI and $FeSO_4{\cdot}7H_2O$ negatively affected the Pestan production, DCW, apparent viscosity, and flocculating activity response. Aeration variable was shown to have a positive effect on only the flocculating activity response among Pestan production, DCW, and apparent viscosity responses. In comparison of the positive and negative variables media conditions, Pestan production and flocculating activity differed by about 9 and 125 times, respectively. In particular, at the jar fermentor level, the aeration variable was the most important factor of the all responses (pestan production, DCW, apparent viscosity, flocculating activity, and anionic charge density). The flocculating activity and apparent viscosity of Pestan were closely related to the molecular chain length and charge density.

• KSBB Journal
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• v.10 no.2
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• pp.176-182
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• 1995

The environmental and physiological factors affecting the production of exopolysaccharide (Methylan) and Poly-${\beta}$-hydroxybutyrate(PHB) by Methylobacterium organophilum were investigated. The maximum PHB content was obtained at $38^{\circ}C$ whereas maximum polysaccharide concentration was $3.54g/\ell$ at $30^{\circ}C$. Optimum pH was pH 7-8 for PHB production and pH 6-7 for polysaccharide production, respectively. Under the condition of $Mo^{2+}, Mg^{2+} or Mn^{2+}$ limitation with nitrogenlimitation, the PHB accumulation was increased, whereas the polysaccharide production was decreased as compared with that of solenitrogenlimitation. Under the condition of sole K+ limitation, cell growth was significantly inhibited and no polysaccharide was produced. However, the PHB content was as high as 60% of dry cell weight. Effect of C/N ratios (methanol/ammonium) in the feeding solution was examined for the simultaneous production of polysaccharide and PHB. The higher ratio of C/N showed the lower cell growth, higher content of PHB in cells, and higher yield of polysaccharide.

• Journal of Microbiology and Biotechnology
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• v.30 no.12
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• pp.1854-1861
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• 2020

Staphylococcus aureus is one of the most common microorganisms and causes foodborne diseases. In particular, biofilm-forming S. aureus is more resistant to antimicrobial agents and sanitizing treatments than planktonic cells. Therefore, this study aimed to investigate the anti-biofilm effects of cell-free supernatant (CFS) of Saccharomyces cerevisiae isolated from cucumber jangajji compared to grapefruit seed extract (GSE). CFS and GSE inhibited and degraded S. aureus biofilms. The adhesion ability, auto-aggregation, and exopolysaccharide production of CFS-treated S. aureus, compared to those of the control, were significantly decreased. Moreover, biofilm-related gene expression was altered upon CFS treatment. Scanning electron microscopy images confirmed that CFS exerted anti-biofilm effects against S. aureus. Therefore, these results suggest that S. cerevisiae CFS has anti-biofilm potential against S. aureus strains.

• Preventive Nutrition and Food Science
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• v.21 no.2
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• pp.117-123
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• 2016

Bioconversion of aglycone-formed isoflavones from glycoside-formed isoflavones by commercial lactic acid bacteria in fermented soybean paste was evaluated. Enterococcus faecium KCTC 13410 showed the most resistant capacity and Lactobacillus acidophilus KCTC 3925 had a sensitive susceptibility at a high NaCl concentration (13.2%) in fermented soybean paste. Among the 5 strains tested, Lac. acidophilus KCTC 3925 showed the highest relative ratio of aglycone-formed isoflavones to total isoflavones in fermented soybean paste. Production of exopolysaccarides (EPS) by lactic acid bacteria was compared using de Man, Rogosa, and Sharpe medium containing 1% sucrose at $37^{\circ}C$ for 48 h. Among the 5 lactic acid bacteria, Lac. acidophilus KCTC 3925 and Lactobacillus rhamnosus KCTC 3929 were investigated to produce EPS. Based on the results concerning growing susceptibility and conversion of aglycone-formed isoflavones/EPS production, it is anticipated that Lac. acidophilus KCTC 3925 may be used for preparation of Cheonggukjang, which contains relative low NaCl content.

• Journal of Microbiology and Biotechnology
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• v.32 no.1
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• pp.56-63
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• 2022

This study aims to determine the antibiofilm effect of cell-free supernatant (CFS) of Lactobacillus brevis strains against Streptococcus mutans strains. To study the antibiofilm mechanism against S. mutans strains, antibacterial effects, cell surface properties (auto-aggregation and cell surface hydrophobicity), exopolysaccharide (EPS) production, and morphological changes were examined. The antibiofilm effect of L. brevis KCCM 202399 CFS as morphological changes were evaluated by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM), compared with the control treatment. Among the L. brevis strains, L. brevis KCCM 202399 showed the highest antibiofilm effect on S. mutans KCTC 5458. The antibacterial effect of L. brevis KCCM 202399 against S. mutans KCTC 5458 was investigated using the deferred method (16.00 mm). The minimum inhibitory concentration of L. brevis KCCM 202399 against S. mutans KCTC 5458 was 25.00%. Compared with the control treatment, L. brevis KCCM 202399 CFS inhibited the bacterial adhesion of S. mutans KCTC 5458 by decreasing auto-aggregation, cell surface hydrophobicity, and EPS production (45.91%, 40.51%, and 67.44%, respectively). L. brevis KCCM 202399 CFS inhibited and eradicated the S. mutans KCTC 5458 biofilm. Therefore, these results suggest that L. brevis KCCM 202399 CFS may be used to develop oral health in the probiotic industry.