• Journal of Life Science
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• v.15 no.4 s.71
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• pp.578-583
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• 2005

Cell-free culture broth of marine halophilic bacterium, Kordia algicida was shown to possess specific algicidal ability against red tide organism, Cochlodinium polykrikides. Physiochemical characteristics of algicidal material originated in the bacterial culture broth were analyzed that its molecular weight was estimated to a 3,000 dalton and it was stable in heat and pH treatment. The algicidal fraction against C. polykrikoides obtained from gel permeable chromatography contained high concentration of ammonium ion as analyzed by ICP/Mass spectrum. C. polykrikoides by the fraction was quickly lysed within 1 min. It was shown that the effective concentration for algicide against C. polykrikoides was over 1mM of ammonium chloride. On the other hand, other metal ions presented in the algicidal fraction showed no algicidal effect against C. polykrikoides. In additon, ammonium ion exhibited species-specific killing spectrum for two species of red tide organisms, C. polykrikoides and Gymnodinium sanguieum. Therefore, further researches on the killing mechanism against C. polykrikoides exerted by ammonium ion, and subsequent development of replaceable algicidal materials will perform to provide useful tools for the control of red tide.

• Food Engineering Progress
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• v.15 no.4
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• pp.289-296
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• 2011

Twenty four fractions by solvent extraction and/or acid precipitation from fruit body and culture broth of Inonotus obliquus were prepared, and their inhibitory effect against acetylcholinesterase (AChE) was investigated. Among these fractions, acid (1 M HCl) precipitates from cell-free culture broth and fruit body exhibited the highest inhibitory effect on AChE in vitro. Acid precipitates inhibited AChE activity in a concentration-dependant manner and $IC_{50}$ values of both acid precipitates were 0.53 mg/mL. The inhibition pattern was general non-competitive inhibition. The energetic parameters were also determined by dual substrate/temperature design. Both acid precipitates increased the values of Ea, ${\Delta}H,/;{\Delta}G$ and ${\Delta}H^{\ast}$ decreasing the value of ${\Delta}S$ for AChE. The results implied that the acid precipitates from I. obliquus increased the thermodynamic barrier, leading to the breakdown of ES complex and the formation of products as inhibitory mechanism.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.407-418
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• 2015

This study is focused on establishing the optimal conditions to enhance the production of antilisterial substances by Lactobacillus paracasei BK57 isolated from Baikkimchi. In addition, the growth and in situ lactic acid and bacteriocin production of this strain were investigated during the manufacture of fresh cheese. And then the efficacy of using Lactobacillus starter as a protective culture to improve the safety of fresh cheese against Listeria monocytogenes KCTC 3569 was estimated. Maximum growth rate and activity of antibacterial substances were obtained in Lactobacilli MRS broth at $37^{\circ}C$ with controlled pH 6.0 after 30 h of incubation under aerobic condition. However, the growth rate and antimicrobial activity of bacteriocin produced in whole milk supplemented with yeast extract (2.0%) as a substrate were lower than those obtained in MRS broth. Live cells and cell-free culture supernatant of BK57 strain were effective in the suppression of L. monocytogenes in milk, whereas the inhibitory of the bacteriocin obtained from BK57 strain was higher in BHI broth than in milk. During storage at $4^{\circ}C$ and $15^{\circ}C$ for 6 days, no significant difference was found in the cell viability and antimicrobial activity of BK 57 strain in fresh cheese. In samples held at two temperatures, there was at least a 15% reduction in the numbers of the pathogen in fresh cheese artificially contaminated with approximately $10^5CFU/ml$ of L. monocytogenes within 6 days. Our results demonstrated the usefulness of L. paracasei BK57 having antilisterial activity as a biopreservative in the cheese making process.

• Journal of Microbiology and Biotechnology
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• v.33 no.1
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• pp.75-82
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• 2023

Lactic acid bacteria (LAB) isolated from kimchi (a traditional Korean dish typically made of fermented cabbage) can provide various health benefits, including anti-obesity, antioxidant, antiinflammatory, anticancer, and antimicrobial effects. In this study, we examined the antimicrobial and immunomodulatory effects of Lactiplantibacillus plantarum WiKim0125 cultured in de Man, Rogosa, and Sharpe (MRS) medium containing vegetable waste. Live bacterial cells were eliminated via supernatant filtration or heat treatment. The cell-free supernatant (CFS) obtained from culture broth containing kimchi cabbage waste (KCW), cabbage waste (CW), or onion waste (OW) showed significantly higher antimicrobial activity against skin pathogens (Propionibacterium acnes and Staphylococcus aureus) and foodborne pathogens (Escherichia coli and Salmonella typhimurium), with inhibition zones ranging between 4.4 and 8.5 mm, compared to that in conventional MRS medium (4.0-7.3 mm). In lipopolysaccharide-stimulated RAW264.7 cells, both supernatant and heat-inactivated Lb. plantarum WiKim0125 from culture media containing KCW and CW suppressed the production of inflammatory cytokines (72.8% and 49.6%, respectively) and nitric oxide (62.2% and 66.7%, respectively) without affecting cell viability. These results indicate that vegetable waste can potentially increase the antimicrobial and immunoregulatory potency of LAB while presenting a molecular basis for applying postbiotics to health products.

• Journal of Microbiology
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• v.39 no.2
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• pp.146-148
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• 2001

Lactobacillus crispatus ATCC 33820 and L. gasseri ATCC 33323 were grown in MRS broth (pH 6.5) at 37$^{\circ}C$ for 24 h and the antibacterial activities of cell free culture supernatants were determined by the agar well diffusion method. The culture supernatants were inhibitory to Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, Enterococcus faecalis, Pediococcus acidilacticii, and Lactobacillus helveticus. The supernatants did not show any lysozyme activity. Addition of catalase did not affect the antibacterial activities of the supernatants. The antibacterial substances were heat stable (100$^{\circ}C$ for 60 min) and sensitive to proteases.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.1
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• pp.90-95
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• 2005

Lactic acid bacteria were isolated from silage, which produce high level of hydrogen peroxide in cell culture supernatant. The 16S rDNA sequences of the isolate matched perfectly with that of Lactobacillus fermentum (99.9%), examined by a 16S rDNA gene sequence analysis and similarity search using the GenBank database, thus named L. fermentum CS12-1. L. fermentum CS12-1 showed resistance to low pH and bile acid. The production of hydrogen peroxide by L. fermentum CS12-1 was confirmed by catalase treatment and high-performance liquid chromatography. L. fermentum CS12-1 accumulated hydrogen peroxide in culture broth as cells grew, and the highest concentration of hydrogen peroxide reached 3.5 mM at the late stationary growth phase. The cell-free supernatant of L. fermentum CS12-1 both before and after neutralization inhibited the growth of enterotoxigenic Escherichia coli K88 that causes diarrhea in piglets.

• Journal of Microbiology and Biotechnology
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• v.29 no.8
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• pp.1204-1211
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• 2019

Fungal exopolysaccharides are important natural products having diverse biological functions. In this study, exopolysaccharides from Fomitopsis castanea mycelia (FEPS) were prepared, and the highest mushroom tyrosinase inhibitory activity was found. FEPS were prepared from cultivation broth by ethanol precipitation method. The extraction yield and protein concentration of FEPS were 213.1 mg/l and 0.03%, respectively. FEPS inhibited mushroom tyrosinase with the half maximal inhibitory concentration ($IC_{50}$) of 16.5 mg/ml and dose-dependently inhibited cellular tyrosinase activity (63.9% at $50{\mu}g/ml$, and 83.3% at $100{\mu}g/ml$) in the cell-free extract of SK-MEL-5 human melanoma cell and ${\alpha}$-melanocyte-stimulating hormone (${\alpha}-MSH$)-stimulated melanin formation in intact SK-MEL-5 human melanoma cell. The $IC_{50}$ of FEPS against NO production from RAW264.7 macrophage cells was $42.8{\pm}0.64{\mu}g/ml$. By in vivo study using a zebrafish model, exposure of FEPS at $400{\mu}g/ml$ to dechorionated zebrafish embryos for 18 h decreased the pigment density, compared to that without FEPS-treated control.

• Journal of Microbiology and Biotechnology
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• v.3 no.3
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• pp.174-180
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• 1993

A strain SMF14 producing an extracellular $\beta$-lactamase was isolated from soil and identified to be a strain of Streptomyces aureofaciens. $\beta$-Lactamase was purified from the cell free culture broth through batchwise hydroxyapatite adsorption, anion exchange chromatography on DEAE Sephadex A-50, gel filtration on Sephadex G-75, and adsorption chromatography on hydroxyapatite. The molecular mass was estimated to be about 43 kDa by SDS-PAGE. The $\beta$-lactamase had substrate specificity to penicillins and it was inhibited by clavulanic acid, being classified to the group 2a of penicillinase.. The optimal reaction pH and temperature were pH 6.0~7.5 and $50^{\circ}C$. The $K_m, and V_{max}$ values of $\beta$-lactamase for penicillin G were calculated to be 1.72 mM and 5.4$\times$$10^5 \mu M \cdot min^{-1}$, respectively.

• Korean Journal of Microbiology
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• v.46 no.2
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• pp.207-212
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• 2010

A bacterium producing the extracellular mannanase was isolated from Korean soybean paste. The isolate WL-8 has been identified as Bacillus subtilis on the basis on its 16S rRNA sequence, morphology and biochemical properties. The mannanase productivity of strain WL-8 was increased in LB broth by addition of wheat bran. The maximum mannanase productivity was reached to approximately 20 U/ml in LB medium supplemented with 6% wheat bran. A gene encoding the mannanase of WL-8 was cloned into Escherichia coli and its nucleotide sequence was subsequently determined. The mannanase gene consisted of 1,086 nucleotides encoding a polypeptide of 362 amino acid residues. The deduced amino acid sequence was highly homologous with those of several mannanases from B. subtilis belonging to GH family 26. Reaction temperature and pH profiles were investigated using the culture filtrate and cell-free extract of the recombinant E. coli carrying a WL-8 mannanase gene, respectively. Optimal conditions for the two fractions occurred at pH 5.5 and $60^{\circ}C$. The cell-free extract showed higher mannanase activity than the culture filtrate at above $60^{\circ}C$.

• Journal of Microbiology and Biotechnology
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• v.19 no.6
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• pp.566-572
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• 2009

Lentinus edodes is a well-known edible and medicinal mushroom used in Oriental cultures. Recently, L. edodes has attracted a lot of attention owing to its antifungal activity, antibacterial activity, antiviral activity, hepatoprotective effect, antitumor activities, and immunomodulatory and cytotoxic effects. In this study, the water-soluble crude polysaccharides, CPF and CPB, which were obtained from the fruiting body and culture cell-free broth of L. edodes by hot-water extraction and ethanol precipitation, were fractionated by DEAE cellulose and Sepharose CL-6B column chromatography, resulting in six polysaccharide fractions, CPFN-G-I, CPFN-G-II, CPFN-G-III, CPFA-G, CPBN-G, and CPBA-G Among these fractions, CPFN-G-I, CPBN-G, and CPBA-G were shown to stimulate the functional activation of macrophages including NO production, cytokine expression, and phagocytosis.