• Food Engineering Progress
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• v.23 no.3
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• pp.209-216
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• 2019

The effects of fermentation on soy embryo have been investigated using lactic acid bacteria, Lactobacillus acidophilus (LA), Lactobacillus bulgaricus (LB), Streptococcus thermophilussei (ST), and Lactobacillus plantarum (LP). As a result of the fermentation test of the isoflavone conversion by strain type, inoculation content, and fermentation time, the optimum conditions were LP bacterium, an inoculum amount of 5%, and a fermentation time of 24 hours. The composition of the isoflavone glycosides in the control was the highest in the order of glycitin> daidzin> genistin. When fermented with lactic acid bacteria, glycoside content decreased, and aglycone content increased. The order of composition was daidzein>glycitein>genistein. In the fermentation with LP bacterium, soyasaponin Ab content decreased and Ba and Bb content increased. Upon assessing the result of the experiment, it was found that the pH of the fermentation broth had a great influence in the bioconversion of isoflavone and soyasaponin. In the case of fermentation by pH 6 broth, aglycone and Bb content was the highest. The increase of aglycone content by fermentation reaction with the LP bacterium can increase the physiological activity and functionalization of soy embryo, which is a byproduct of processing.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.6
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• pp.819-827
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• 2017

Objective: Four lactic acid bacteria (LAB) strains isolated from common vetch, tall fescue and perennial ryegrass on the Tibetan Plateau were characterized, and their effects on the fermentation quality of Italian ryegrass (Lolium multiflorum Lam.) silage were studied. Methods: The four isolated strains and one commercial inoculant (G, Lactobacillus plantarum MTD-1) were evaluated using the acid production ability test, morphological observation, Gram staining, physiological, biochemical and acid tolerance tests. The five LAB strains were added to Italian ryegrass for ensiling at three different temperatures ($10^{\circ}C$, $15^{\circ}C$, and $25^{\circ}C$). Results: All isolated strains (LCG3, LTG7, I5, and LI3) could grow at $5^{\circ}C$ to $20^{\circ}C$, pH 3.0 to 8.0 and NaCl (3.0%, 6.5%). Strains LCG3, LTG7, I5, and LI3 were identified as Lactobacillus plantarum, Pediococcus acidilactici, Lactobacillus paraplantarum, and Lactobacillus casei by sequencing 16S rDNA, respectively. All LAB inoculants significantly (p<0.05) increased lactic acid (LA) contents and ratios of lactic acid to acetic acid, and reduced pH and ammonia nitrogen/total nitrogen (AN/TN) compared with uninoculated silages at various temperatures ($10^{\circ}C$, $15^{\circ}C$, and $25^{\circ}C$). Compared to the commercial inoculant G, I5, and LI3 showed similar effects on improving the silage quality of Italian ryegrass at $10^{\circ}C$ and $15^{\circ}C$, indicated by similar pH, LA content and AN/TN. Conclusion: All inoculants could improve the silage fermentation quality at various temperatures ($10^{\circ}C$, $15^{\circ}C$, and $25^{\circ}C$). At the temperature of $10^{\circ}C$ and $15^{\circ}C$, strain I5 and LI3 had similar effects with the commercial inoculant G on improving the silage quality of Italian ryegrass.

• Journal of Food Hygiene and Safety
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• v.34 no.6
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• pp.591-594
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• 2019

Some strains of Escherichia coli are categorized as pathogenic bacteria and alternative antimicrobials including bacteriophages for controlling these bacteria have been studied. In this study we screened antimicrobial candidates that present synergistic inhibition of the growth of E. coli DH5α as a model when co-treated with the bacteriophage ECP27 to target the bacteria. As candidates, CaCl₂, lactic acid, and citric acid were tested. CaCl₂ showed a synergistic inhibition against the strain by dose-dependent manner at 6 h of incubation but the viable cell count was recovered at 12 h. However, lactic acid and citric acid at 30 mM concentration showed synergistic inhibitions at 6 h of incubation and cleared the viable cells of E. coli DH5α at 12 h when co-treated with the bacteriophage even though lactic acid or citric acid alone was effective. Therefore, co-treatment using the bacteriophage and organic acids such as lactic acid and citric acid can be a solution for synergistic inhibition of the growth of E. coli.

• Korean Journal of Microbiology
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• v.50 no.1
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• pp.8-14
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• 2014

The objective of this work is to investigate and compare several functional properties of lactic acid bacteria (LAB), Lactobacillus casei SK-7 isolated from home-made yogurt and Lactobacillus bulgaricus YK-11 from commercial yogurt. Initially, physiological and biochemical properties of SK-7 and YK-11 were characterized. Phylogenetic analysis using 16S rRNA sequencing were performed to identify the strains, and the strain could be assigned to Lactobacillus casei and Lactobacillus bulgaricus, designated as L. casei SK-7 and L. bulgaricus YK-11. Phylogenetic tree of SK-7 and YK-11 was plotted based on 16S rRNA sequence comparisons. Production of lactic acid and organic acid, and pH changes in the cultures of SK-7 and YK-11 were monitored during 72 h. During the incubation period, several functional properties of L. casei SK-7 and L. bulgaricus YK-11 were examined. L. casei SK-7 and L. bulgaricus YK-11 cultures eliminated 93.9% and 88.2% of nitrite, respectively. Antioxidant activity of cultural supernatants of SK-7 and YK-11 were 62.6%, 54.9%, and activity of ${\beta}$-galactosidase were 14.9 units/mg and 13.1 units/mg, respectively. The antimicrobial activities were examined with 20-fold concentrated culture supernatants from the cultures of SK-7 and YK-11. The activities of SK-7 supernatants were clearly observed against all microorganisms in this work, whereas no activities were observed in YK-11 supernatants. Although it might be conducted additional functional research, functional properties of LAB isolated from home-made yogurt have been shown to be better than those of commercial yogurt in this work.

• Journal of Society of Preventive Korean Medicine
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• v.16 no.3
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• pp.139-153
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• 2012

Objectives : NK cells are spontaneously cytotoxic lymphocytes. These are not only important parts in the first line of defence against bacterial and viral infections of outside, but they may also play a critical role in chronic viral diseases. NK cells kill their targets spontaneously, without the need for prior sensitization and class I MHC restriction by the regulation of cytolytic functions and secretion of a variety of cytokines, such as interleukin-12(IL-12), MCP-1, IL-6, TNF-${\alpha}$, IFN-${\gamma}$. In addition, macrophage and NK cells cooperate through the production of cell mediates. These cooperation and modulation are one of major factors to prevent for evading immune surveillance of cancer. Hence, it could be assumed that if any candidate to enhance activities of macrophage and NK cell, it is considered as a potentially useful agents against cancer. Methods : In our study, to investigate effect of fermented soybean extracts by Lactic acid bacteria (SFE, soybean fermented extracts) work on intestinal immune cell to maintain general immune modulating and anti-cancer activity. We analyzed NK cytotoxicity assay and gene expressions of cytokine related with macrophage and NK cell activity. Results : In vitro experiment, SFE was verified as safety material for cell toxicicty to tumor cell strain without any toxicity of tumor growth inhibition and various cell strain. Effects of macrophage activity stimulating directly by SFE measured induced cytokine. The studies showed that IL-12 production by stimulation of SFE depended on concentration from 0.16mg/mL to 0.63mg/mL with non toxicity to cell, and it was the best activity at 0.63mg/mL. Besides, the effective concentration of SFE producing TNF-${\alpha}$ is similar to IL-12, but it was the best activity at 1.25mg/mL. The level of MCP-1, IL-6 and IFN-${\gamma}$ depended on concentration from 0.16mg/mL to 10mg/mL, IFN-${\gamma}$ showed the best activity at the effective concentration of 0.63mg/mL. With the result of NK cell activity measurement, the spleen cell of mouse injected SFE had 1.5 times higher killing effect than non injected cell. Conclusions : The result of this studies is that Soybean fermetated extracts(SFE) has possibility to immune aided material for the function not only inhibition of microbial infection to macrophage but also activity of adaption immune and cellular immune system.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.11
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• pp.1626-1631
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• 2012

Sixty strains of lactic acid bacteria were isolated from kimchi and used as a starter for fermented tofu. Among the isolated strains, strain KL-6 showed antimicrobial activity against various pathogens, antioxidative activity, and viability in artificial gastric juice and artificial bile acid. The selected strain KL-6 was identified as Pediococcus acidilactici KL-6 by morphological and physiological tests, including Gram staining, catalase test, and 16S rRNA sequencing. The fermentation characteristics of tofu with a kimchi ingredient mixture (Control) consisting of red pepper, garlic, ginger, sugar, salt, jeotgal, and juice of chinese cabbage were compared with those of tofus inoculated with strain KL-6 and the kimchi ingredient mixture (TL) or a pre-fermented kimchi ingredient mixture (TPL) for 24 hr at $37^{\circ}C$. The pH levels of all tested tofu samples decreased after 1 week of fermentation, reaching 3.96 (control), 3.97 (TL), and 4.03 log cfu/g (TPL) after fermentation for 14 weeks at $20^{\circ}C$. Total aerobe content of fermented tofu increased until 2 weeks of fermentation, but decreased steadily thereafter. The number of lactic acid bacteria reached $10^6$ cfu/g after 1 week of fermentation in TL and TPL, whereas it took 2 weeks for the control. The number of lactic acid bacteria in all tested tofu samples reached $10^3$ cfu/g after 14 weeks of fermentation at $20^{\circ}C$. Coliform bacteria were not detected in TL or TPL after 1 week of fermentation. The sensory scores of TL and TPL were higher than that of control in terms of taste, flavor, texture, and overall acceptability. The sensory quality of TPL was the best among all tested fermented tofu samples.

• Journal of Microbiology and Biotechnology
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• v.19 no.2
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• pp.178-186
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• 2009

To examine their potential as probiotics, acid and bile tolerance, antibiotics resistance, adhesion capacity to Caco-2 and HT-29, and antibacterial activity, of LAB isolated from Korean fermented foods such. as dongchimi, kimchi, Meju, and doenjang were assayed against foodborne pathogenic bacteria. DC 55, DC 136, DC 222, KC 21, KC 24, KC 34, KC 43, KC 117, MJ 54, MJ 301, SP 33, and SP 170 strains were resistant to acid and bile conditions. In particular, DC 55, DC 136, KC 24, KC 43, and MJ 301 strains were highly resistant to higher than 20 ${\mu}g/ml$ concentrations of vancomycin, streptomycin sulfate, or amoxicillin, whereas, DC 222, KC 21, KC 34, KC 117, MJ 54, and SP 33 strains were susceptible to lower than 2 ${\mu}g/ml$ concentrations of those antibiotics. The adhesion to HT-29 and Caco-2 cells varied with the strains tested in a strain-dependent manner. The highest level of adhesion was observed with DC 55, KC 21, KC 24, and MJ 301 strains, having higher than 50% of adhesion to HT-29 or Caco-2 cells. In addition, Staphylococcus aureus was the most sensitive to KC 21, showing an inhibition of about 70%, and the antibacterial activity of KC 21 against S. aureus resulted most likely from both organic acids and bacteriocin. Based on its phenotypic characteristics and utilization of various sugars, the KC 21 strain was identified as Lactobacillus plantarum.

• Food Science of Animal Resources
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• v.38 no.6
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• pp.1315-1321
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• 2018

Bacteriocin is ribosomally synthesized by bacteria and inhibits closely related species. In this study we aimed at isolating lactic acid bacteria producing bacteriocin presenting anti-staphylococcal activity. A Lactococcus lactis strain was isolated from kimchi for the purpose and identified by 16S rRNA gene sequencing. As preliminary tests, optimal culture conditions, stabilities against heat, solvents, and enzymes treatments, and type of action (bacteriostatic or bactericidal) of the bacteriocin were investigated. The optimal culture conditions for production of the bacteriocin were MRS broth medium and $25^{\circ}C$ and $30^{\circ}C$ culture temperatures. The bacteriocin was acidic and the activity was abolished by a protease treatment. Its stability was maintained at $100^{\circ}C$ for 15 min and under treatments of various organic solvents such as methanol, ethanol, acetone, acetonitrile, and chloroform. Finally, the bacteriocin showed bactericidal action against Staphylococcus aureus where 200 AU/mL of the bacteriocin decreased the viable cell count (CFU/mL) of S. aureus by 2.5 log scale, compared with a control (no bacteriocin added) after 4-h incubation.

• Food Science and Preservation
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• v.3 no.2
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• pp.171-178
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• 1996

This study was carried out for the purpose of improving the persimmon vinegar. The acetic acid bacteria strain JST-3, using acetic acid fermentation was isolated from the traditional persimmon vinegar. The optimum conditions for high yield of acetic acid were studied in the shaking bath. Acetic acid bacteria was cultured at 3$0^{\circ}C$ for 4 days and transferred to persimmon alcoholic juice for acetic acid fermentation. The optimum initial acidity for acetic acrid fermentation was 1%(w/v) and the addition of glucose or yeast extract was observed to produce relatively low yield of acetic acid. Succinic and acetic acid were major organic acid in the persimmon vinegar, The contents of lactic acid which was known to increase off-flavor were very low. Sensory evaluation revealed that the persimmon vinegar prepared in this study was superior to two commercial ones in the aroma and taste.

• Journal of Microbiology and Biotechnology
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• v.14 no.4
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• pp.680-685
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• 2004

The capability of lactic acid bacteria (LABs) to adhere to intestinal epithelial cells and vaginal epithelial cells is an important factor in the formation of a barrier to prevent the colonization of pathogenic bacteria. In addition, the ability to coaggregate with pathogens and production of antimicrobial agents also allow LABs to fight against pathogens. In this work, Weissella confusa PL9001 was tested for its ability to inhibit the growth and adherence of genitourinary pathogens, including Candida albicans, Escherichia coli, Staphylococcus aureus, and vancomycin-resistant Enterococcus faecium (VRE), isolated from the urine of hospitalized female patients. W. confusa PL9001 was found to coaggregate with the four pathogens, as observed with a light microscope and scanning electron microscope. In competition, exclusion, and displacement tests, the adherence of the pathogens to T24 bladder epithelial cells was also inhibited by W. confusa PL9001. Accordingly, these results suggest that W. confusa PL9001 is potentially useful for both preventive and therapeutic treatment of genitourinary infections.