• Journal of Microbiology and Biotechnology
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• 제28권7호
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• pp.1052-1060
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• 2018

Numerous studies suggest that the effects of lactic acid bacteria (LAB) on oxidative stress in vivo are correlated with their antioxidative activities in vitro; however, the relationship is still unclear and contradictory. The antioxidative activities of 27 Lactobacillus plantarum strains isolated from fermented foods were determined in terms of 2,2-diphenyl-1-picrylhydrazyl, hydroxyl radical, and superoxide radical scavenging abilities, reducing activity, resistance to hydrogen peroxide, and ferrous chelating ability in vitro. Two fuzzy synthetic evaluation models, one with an analytic hierarchy process and one using entropy weight, were then used to evaluate the overall antioxidative abilities of these L. plantarum strains. Although there was some difference between the two models, the highest scoring strain (CCFM10), the middle scoring strain (CCFM242), and the lowest scoring strain (RS15-3) were obtained with both models. Examination of the antioxidative abilities of these three strains in $\text\tiny{D}$-galactose-induced oxidative stress mice demonstrated that their overall antioxidative abilities in vitro could reveal the abilities to alleviate oxidative stress in vivo. The current study suggests that assessment of overall antioxidative abilities with fuzzy synthetic models can guide the evaluation of probiotic antioxidants. It might be a more quick and effective method to evaluate the overall antioxidative abilities of LAB.

• Journal of Microbiology and Biotechnology
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• 제30권5호
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• pp.726-732
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• 2020

Indonesian kefir grains are potential sources of lactic acid bacteria (LAB) that may act as probiotics with specific functional properties. In this study we explored the potential of the probiotic and cholesterol-lowering effect of LAB isolated from Indonesian kefir grains obtained from Bogor, Bandung, Jakarta, and Yogyakarta. The results revealed that 10 isolates showed considerable survivability at low pH and bile salt with total cell reduction of ~3 log colony-forming units per milliliter after exposure to pH 2.5 and 0.5% (w/v) bile salt for 1 and 3 h, respectively. All strains exhibited strong antimicrobial activities against pathogenic bacteria and were sensitive to a wide spectrum of antibiotics but exhibited weak bile salt hydrolase activity. Identification based on 16S RNA suggested that nine isolates were Lactobacillus kefiri and one was Lactobacillus rhamnosus. The ability of the isolates to reduce cholesterol from the media varied, ranging from 22.08% to 68.75% with the highest reduction shown by L. kefiri JK17. The ability to remove cholesterol from the media decreased greatly in resting and dead cells, ranging from 14.58% to 22.08% in resting cells and from 7.89% to 18.17% in dead cells. It can be concluded that Indonesian kefir grains contain LAB potentially acting as probiotics capable of reducing cholesterol. The cholesterol-lowering effect especially occurs when the cells are metabolically active.

• Journal of Dairy Science and Biotechnology
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• 제30권2호
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• pp.75-81
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• 2012

Molds cause severe cheese deterioration, even though some white and blue molds are used for the manufacture of Camembert and Blue cheese, respectively. The species of Geotrichum, Moniliella, Aspergillus, Penicillium, Mucor, Fusarium, Phoma, and Cladosporium are the main fungi that affect contamination during cheese ripening. Once deteriorated by fungal spoilage, cheese becomes toxic and inedible. Fungal deterioration of cheese decreases the nutritional value, flavor profiles, physicochemical and organoleptic properties, and increases toxicity and infectious disease. Fungal contamination during cheese ripening is highly damaging to cheese production in Korean farmstead milk processing companies. Therefore, these companies hesitate to develop natural and ripened cheese varieties. This article discusses the recent and ongoing developments in the removal techniques of fungal contamination during cheese ripening. There are 2 categories of antifungal agents: chemical and natural. Major chemical agents are preservatives (propionic acid, sodium propionate, and calcium propionate) and ethanol. Among the natural agents, grapefruit seed extract, phytoncide, essential oils, and garlic have been investigated as natural antifungal agents. Additionally, some studies have shown that antibiotics such as natamycin and Delvocid$^{(R)}$, have antifungal activities for cheese contaminated with fungi. Microbial resources such as probiotic lactic acid bacteria, Propionibacterium, lactic acid bacteria from Kimchi, and bacteriocin are well known as antifungal agents. In addition, ozonization treatment has been reported to inhibit the growth activity of cheese-contaminating fungi.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2001년도 Proceedings of 2001 International Symposium
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• pp.155-157
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• 2001

Bifidobacterium spp. is nonpathogenic, gram-positive and anaerobic bacteria, which inhabit the intestinal tract of humans and animals. In breast-fed infants, bifidobacteria comprise morethan 90％ of the gut bacterial population. Bifidobacteria spp. are used in commericial fermented dairy products and have been suggested to exert health promoting effects on the host by maintaining intestinal microflora balances, improving lactose tolerance, reducing serum cholesterol levels, increasing synthesis of vitamins, and aiding the immune enchancement and anticarcinogenic activity for the host. These beneficial effects of Bifidobacterium are strain-related. Therefore continued efforts to improve strain characteristics are warranted. in these respect, development of vector system for Bifidobacterium is very important not only for the strain improvement but also because Bifidobacterium is most promising in serving as a delivery system for the useful gene products, such as vaccine or anticarcinogenic polypeptides, into human intestinal tract. For developing vector system, we have characterized several bifidobacterial plasmids at genetic level and developed several shuttle vectors between E. coli and Bifidobacterium using them. Also, we have cloned and sequenced several metabolic genes and food grade selection marker. Also we have obtained bifidobacterial surface protein, which will be used as the mediator for surface display of foreign genes. Recently we have succeeded in expressing amylase and GFP in Bifidobacterium using our own expression vector system. Now we are in a very exciting stage for the molecular breeding and safe delivery system using probiotic Bifidobacterium strains.

• 한국축산식품학회지
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• 제34권6호
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• pp.829-835
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• 2014

Inflammatory bowel disease (IBD) is caused by dysregulation of colon mucosal immunity and mucosal epithelial barrier function. Recent studies have reported that lipoteichoic acid (LTA) from Lactobacillus plantarum K8 reduces excessive production of pro-inflammatory cytokine. In this study, we investigated the preventive effects of lysate of Lb. plantarum K8 in dextran sulfate sodium (DSS)-induced colitis. Male Sprague-Dawley rats were orally pretreated with lysate of Lb. plantarum K8 (low dose or high dose) or live Lb. plantarum K8 prior to the induction of colitis using 4% DSS. Disease progression was monitored by assessment of disease activity index (DAI). Histological changes of colonic tissues were evaluated by hematoxylin and eosin (HE) staining. Tumor necrosis factor-alpha (TNF-${\alpha}$), interleukin-6 (IL-6) levels were measured using enzyme-linked immunosorbent assay (ELISA). The colon mRNA expressions of TNF-${\alpha}$, IL-6, and toll like receptor-2 (TLR-2) were examined by quantitative real-time-transcription polymerase chain reaction (qPCR). Lysate of Lb. plantarum K8 suppressed colon shortening, edema, mucosal damage, and the loss of DSS-induced crypts. The groups that received lysate of Lb. plantarum K8 exhibited significantly decreased levels of the pro-inflammatory cytokines TNF-${\alpha}$ and IL-6 in the colon. Interestingly, colonic expression of toll like receptor-2 mRNA in the high-dose lysate of Lb. plantarum K8 group increased significantly. Our study demonstrates the protective effects of oral lysate of Lb. plantarum K8 administration on DSS-induced colitis via the modulation of pro-inflammatory mediators of the mucosal immune system.

• 한국축산식품학회지
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• 제36권5호
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• pp.635-640
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• 2016

Lactobacillus acidophilus n.v. Er2 317/402 strain Narine is known as a health beneficial functional probiotic culture and supplementary source of nutrition for newborns. In this study, in vitro antimicrobial activities of Narine-lyophilized (Narine-L), Narine-heat treated (Narine-HT), and Narine crude cell-free extract (Narine-CCFE) were evaluated against pathogen Cronobacter sakazakii (C. sakazakii) in agar as well as in a reconstituted powdered infant formula (RPIF) model. Inhibition zones of 30 mg Narine-L and Narine-HT were both 150 U, whereas inhibition zone of 30 mg Narine-CCFE was 200 U. Narine-L (1 g) and Narine-HT (1 g) were added to 10 mL of artificially contaminated RPIF, respectively, containing 100 μL of C. sakazakii (1.62×10⁸ colony forming unit (CFU)/mL). After treatment with Narine-L and Narine-HT for 3 h and 6 h at 37℃, less than ≤107 CFU/mL of C. sakazakii was detected in RPIF. Without Narine-L and Narine-HT treatment, the population of C. sakazakii increased up to 5.36×10⁹ CFU/mL after 6 h. Examination by transmission electron microscopy confirmed C. sakazakii cells were damaged by Narine-CCFE. Thus, employing Narine culture as a natural and safe bio-preservative may protect infants from C. sakazakii.

• Journal of Microbiology and Biotechnology
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• 제18권7호
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• pp.1266-1273
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• 2008

Lactic acid bacteria (LAB) with antimicrobial activity and high exopolysaccharide (EPS) production ability isolated from sourdough were studied for their fermentation characteristics as potential new starter cultures. The values of pH, titratable acidity, and viable cell counts were $4.06{\pm}0.009-4.50{\pm}0.015,\;0.787{\pm}0.020%-1.172{\pm}0.018%,\;and\;8.78{\pm}0.08-8.98{\pm}0.06$ log CFU/ml, respectively. In order to select probiotics with a high survival rate in the gut, isolates were tested to assess resistance against the artificial gastric acid and bile juice. Viable LAB counts were significantly (p<0.05) affected by the acidity. At pH 2.0, the total declines in the initial bacterial counts were 4.52$\pm$0.07 log for S. thermophilus St-Body-1, >7.98$\pm$0.03 log for E. flavescens DU-10, >7.95$\pm$0.05 log for E. faecium DU-12, and 3.15$\pm$0.06 log for L. amylovorus DU-21. Among the strains, L. amylovorus DU-21 was the only strain that had bile tolerance under simulated gastrointestinal conditions. In order to improve EPS production by L. amylovorus DU-21, the influence of carbon source was studied. When glucose was used as a carbon source, EPS production dramatically increased to 17.19$\pm$0.28 g/l (p<0.05). The maximum cell growth (10.012$\pm$>0.012 log CFU/ml) and EPS production (18.71$\pm$0.19 g/l) were achieved when 15 g/l of glucose was employed as the carbon source.

• 한국식품과학회지
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• 제34권6호
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• pp.1085-1090
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• 2002

Dextransucrase의 수용체반응(acceptor reaction)을 이용하여 판노스(panose)를 포함한 다양한 당전이화합물을 발효식품에서 생성하기 위하여 고활성 dextransucrase를 저온에서 생성하는 Leuconostoc속 균주를 동치미김치로부터 분리 및 선발하였다. 동치미를 제조하여 $8^{\circ}C$에서 발효시키면서 분리한 Leuconostoc속 균주중에서 균체의 증식유도기간(lag phase), 최대균체량(g/L), 균체의 비성장속도$(\mu)$ 및 dextransucrase 활성을 종합적으로 비교하여 우수균주를 선발하였고, 최종적으로 MIDI를 이용하여 Leuc. mesenteroides로 동정하였다. 본 균주는 김치를 포함한 저온성 발효식품에서 당전이화합물을 생성하여 기능성을 부여하는 스타터로 사용될 수 있을 것으로 판단된다.

• Journal of Microbiology and Biotechnology
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• 제31권10호
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• pp.1383-1392
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• 2021

Carbapenem-resistant Enterobacteriaceae (CRE) that produce Klebsiella pneumoniae carbapenemase are increasingly reported worldwide and have become more and more resistant to nearly all antibiotics during the past decade. The emergence of K. pneumoniae strains with decreased susceptibility to carbapenems, which are used as a last resort treatment option, is a significant threat to hospitalized patients worldwide as K. pneumoniae infection is responsible for a high mortality rate in the elderly and immunodeficient individuals. This study used Lactobacillus fermentum as a candidate probiotic for treating CRE-related infections and investigated its effectiveness. We treated mice with L. fermentum originating from the vaginal fluid of a healthy Korean woman and evaluated the Lactobacilli's efficacy in preventive, treatment, nonestablishment, and colonization mouse model experiments. Compared to the control, pre-treatment with L. fermentum significantly reduced body weight loss in the mouse models, and all mice survived until the end of the study. The oral administration of L. fermentum after carbapenem-resistant Klebsiella (CRK) infection decreased mortality and illness severity during a 2-week observation period and showed that it affects other strains of CRK bacteria. Also, the number of Klebsiella bacteria was decreased to below 5.5 log₁₀ CFU/ml following oral administration of L. fermentum in the colonization model. These findings demonstrate L. fermentum's antibacterial activity and its potential to treat CRE infection in the future.

• Journal of Ginseng Research
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• 제43권1호
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• pp.20-26
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• 2019

Background: Ginsenosides, which are bioactive components in ginseng, can be converted to smaller compounds for improvement of their pharmacological activities. The conversion methods include heating; acid, alkali, and enzymatic treatment; and microbial conversion. The aim of this study was to determine the bioconversion of ginsenosides in fermented red ginseng extract (FRGE). Methods: Red ginseng extract (RGE) was fermented using Lactobacillus plantarum KCCM 11613P. This study investigated the ginsenosides and their antioxidant capacity in FRGE using diverse methods. Results: Properties of RGE were changed upon fermentation. Fermentation reduced the pH value, but increased the titratable acidity and viable cell counts of lactic acid bacteria. L. plantarum KCCM 11613P converted ginsenosides $Rb_2$ and $Rb_3$ to ginsenoside Rd in RGE. Fermentation also enhanced the antioxidant effects of RGE. FRGE reduced 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and reducing power; however, it improved the inhibition of ${\beta}$-carotene and linoleic acid oxidation and the lipid peroxidation. This suggested that the fermentation of RGE is effective for producing ginsenoside Rd as precursor of ginsenoside compound K and inhibition of lipid oxidation. Conclusion: This study showed that RGE fermented by L. plantarum KCCM 11613P may contribute to the development of functional food materials.