• Animal Bioscience
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• 제34권9호
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• pp.1479-1490
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• 2021

Objective: Our recent findings confirmed the effectiveness of sodium metabisulfite (SMB) in controlling the growth of undesirable microorganisms in fruit and vegetable discards (FVD); however, lactic acid bacteria (LAB) are susceptible to its antibacterial effects. Two series of experiments were conducted to enable the survivability of LAB during silage fermentation of a total mixed ration (TMR) containing SMB-treated FVD. Methods: In Exp. 1, the objective was to isolate a strain of LAB tolerable to the toxic effect of SMB. In Exp. 2, the SMB load was minimized through its partial replacement with a chemical mixture (CM) based on sodium benzoate (57%), potassium sorbate (29%), and sodium nitrite (14%). FVD was treated with SMB + CM (2 g each/kg biomass) and added to the TMR at varying levels (0%, 10%, or 20%), with or without KU18 inoculation. Results: The KU18 was screened as a presumptive LAB strain showing superior tolerance to SMB in broth medium, and was identified at the molecular level using 16S rRNA gene sequence analysis as Lactobacillus plantarum. Inoculation of KU18 in TMR containing SMB was not successful for the LAB development, biomass acidification, and organoleptic properties of the resultant silage. In Exp. 2, based on the effectiveness and economic considerations, an equal proportion of SMB and CM (2 g each/kg FVD) was selected as the optimal loads for the subsequent silage fermentation experiment. Slight differences were determined in LAB development, biomass acidification, and sensorial characteristics among the experimental silages, suggesting the low toxicity of the preservatives on LAB growth. Conclusion: Although KU18 strain was not able to efficiently develop in silage mass containing SMB-treated FVD, the partial substitution of SMB load with the CM effectively alleviated the toxic effect of SMB and allowed LAB development during the fermentation of SMB + CM-treated FVD in TMR.

• 한국식품과학회지
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• 제31권2호
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• pp.509-515
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• 1999

본 연구에서는 난백분말과 카제인을 기질로 한 시료에 생육촉진물질(growth stimulating agent: GSA)을 첨가하여 젖산균의 생육과 산생성 및 젖산균 발효식품의 관능성과 점도에 미치는 영향을 관찰하였다. GSA 첨가로 젖산균의 산생성이 촉진되었으며, 0.3%보다 1%에서 그 효과가 더 높았다. 시료에 따라서는 GSA 첨가시료의 산도가 우유시료와 차이가 없는 것도 있었다. 그러나 GSA의 첨가로 인한 생균수의 증가는 뚜렷하지 않았다. 세 균주 중에서 L. acidophilus로 발효시킨 시료의 산도가 다른 균주보다 대체적으로 높았다. GSA 첨가농도는 1%가 가장 적합하였다. 발효시간을 달리하여 실시한 시료의 관능검사 결과 18 hr시료의 관능성이 가장 우수하였다. 한편 우유시료에 비하여 GSA 첨가시료는 유청의 분리가 상대적으로 많고, GSA 특유의 맛과 냄새가 있어 전반적인 기호도와 맛이 다소 저조하였다. 우유시료와 control 시료의 점도가 GSA 첨가시료보다 유의적으로 높았고 (p<0.05), GSA를 첨가한 4시료 사이에는 유의적인 차이가 없었다. 모든 시료는 시간이 경과함에 따라 점도가 서서히 감소하는 현상, 즉 thixotopic flow의 특성을 나타냈다.

• 미생물학회지
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• 제53권4호
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• pp.273-285
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• 2017

본 연구에서는 프로바이오틱 유산균이 생산한 항균물질에 의한 바이오제닉 아민 생성균의 제어 효과와 박테리오신 및 유기산의 항균 활성에 영향을 미치는 배양 조건을 조사하였다. Lactobacillus plantarum FIL20 (64 AU/ml) 및 Lactobacillus paracasei FIL31 (128 AU/ml)의 박테리오신 용액은 Serratia marcescens CIH09과 Aeromonas hydrophilia RIH28에 각각 강한 항균 활성을 나타내었고 FIL20과 FIL31 균주로부터 얻은 배양 상등액 내에 유산 함유량은 각각 $107.3{\pm}2.7mM$과 $129.5{\pm}4.6mM$로 나타났다. 따라서 L. plantarum FIL20과 L. paracasei FIL31이 생산한 박테리오신 용액(200 AU/ml) 및 배양 상등액($200{\mu}l/ml$)의 처리에 의해 S. marcescens CIH09 및 A. hydrophilia RIH28의 균수 및 히스타민과 티라민의 생성량을 유의하게 감소시켰다(P < 0.05). 초기 pH (5.0)와 배양 온도($15^{\circ}C$)가 낮은 조건 하에서 CIH09 균주가 생산한 히스타민과 티라민의 생성량은 L. plantarum FIL20이 생산한 박테리오신 용액이나 배양 상등액 처리에 의해 유의하게 감소되었다. 또한 식염 5% 혹은 아질산 칼륨($200{\mu}g/g$)과 FIL20 유산균의 항균물질을 혼용한 경우 바이오제닉 아민을 생성하는 세균의 균수와 유해 아민 함량을 유의하게 감소시켰다(P < 0.05). 결론적으로 L. plantarum FIL20과 L. paracasei FIL31의 박테리오신 및 유기산 용액은 허들 테크놀로지에 적용하여 바이오제닉 아민 생성을 효과적으로 제어할 수 있는 생물학적 보존제로 이용될 수 있을 것이다.

• Journal of Microbiology and Biotechnology
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• 제26권12호
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• pp.2148-2158
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• 2016

To investigate the effects of Lactobacillus curvatus and Leuconostoc mesenteroides on suan cai (pickled Chinese cabbage) fermentation, L. curvatus and/or Ln. mesenteroides were inoculated into suan cai. Physicochemical indexes were measured, and the microbial dynamics during the fermentation were analyzed by Illumina MiSeq sequencing and quantitative polymerase chain reaction (qPCR). The results showed that inoculation with lactic acid bacteria (LAB) lowered the pH of the fermentation system more rapidly. The decrease in water-soluble carbohydrates in the inoculated treatments occurred more rapidly than in the control. The LAB counts in the control were lower than in other inoculated treatments during the first 12 days of fermentation. According to the Illumina MiSeq sequencing analyses, Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, Cyanobacteria, Fusobacteria, and Verrucomicrobia were present in the fermentations, along with other unclassified bacteria. Generally, Firmicutes was predominant during the fermentation in all treatments. At the genus level, 16 genera were detected. The relative abundance of Lactobacillus in all inoculated treatments was higher than in the control. The relative abundance of Lactobacillus in the treatments containing L. curvatus was higher than in the Ln. mesenteroides-only treatment. The relative abundance of Leuconostoc in the Ln. mesenteroides-containing treatments increased continuously throughout the fermentation. Leuconostoc was highest in the Ln. mesenteroides-only treatment. According to the qPCR results, L. curvatus and/or Ln. mesenteroides inoculations could effectively inhabit the fermentation system. L. curvatus dominated the fermentation in the inoculated treatments.

• Journal of Microbiology and Biotechnology
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• 제25권12호
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• pp.2049-2057
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• 2015

Various salt concentrations (1.0%, 1.3%, 1.6%, 1.9%, and 2.1% labeled as sample A, B, C, D, and E, respectively) were investigated for microbial diversity, identification of Lactic Acid Bacteria (LAB) in salted kimchi cabbage, prepared under laboratory conditions. These samples were stored at 4°C for 5 weeks in proper aluminum-metalized pouch packaging with calcium hydroxide gas absorber. A culture-independent method known as polymerase chain reaction - denaturing gradient gel electrophoresis was carried out to identify LAB distributions among various salt concentration samples that had identified 2 Weissella (W. confusa and W. soli), 1 Lactobacillus (Lb. sakei), and 3 Leuconostoc (Lc. mesenteroides, Lc. lactis, and Lc. gelidum) in the overall kimchi samples. The pH, titratable acidity, viable cell counts, and coliform counts were not affected by salt variations. In order to assess sensory acceptance, the conducted sensory evaluation using a 9-point hedonic scale had revealed that samples with 1.3% salt concentration (lower than the manufacturer's regular salt concentration) was more preferred, indicating that the use of 1.3% salt concentration was acceptable in normal kimchi fermentation for its quality and safety. Despite similarities in pH, titratable acidity, viable cell counts, coliform counts, and LAB distributions among the various salt concentrations of kimchi samples, the sample with 1.3% salt concentration was shown to be the most preferred, indicating that this salt concentration was suitable in kimchi production in order to reduce salt intake through kimchi consumptions.

• 대한수의학회지
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• 제56권1호
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• pp.1-7
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• 2016

Lactic acid bacteria (LAB) are commonly used as probiotics in poultry. The present study employed in vitro and in vivo methods to select and test LAB isolated from Muscovy duck ceca as potential probiotics. In the in vitro study, 50 LAB were isolated from Muscovy duck ceca and tested for growth inhibition against Salmonella (S.) Enteritidis. Eleven isolates strongly inhibited S. Enteritidis and only 1 isolate (MD5-2) showing the strongest inhibition was selected for identification. This isolate was called as Lactobacillus (L.) reuteri MD5-2. For the in vivo investigation, 90 1-day-old Muscovy ducks were randomly assigned into three groups of 30 animals each (group 1, control; group 2, treated with $10^8$ colony-forming unit (CFU) of L. reuteri MD5-2 orally once on day 1; and group 3, treated with $10^8CFU$ of L. reuteri MD5-2 orally once daily from days 1 to 5). The ducks were housed in three large cages and raised for 50 days, after which body weight, duodenal villus height and crypt depth were measured. Both villus height and villus height to crypt depth ratio were significantly greater in group 3 than in groups 1 and 2. In conclusion, further investigation of L. reuteri MD5-2 as a potential probiotic strain is warranted.

• Molecules and Cells
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• 제42권11호
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• pp.755-762
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• 2019

Despite decades of research into colorectal cancer (CRC), there is an ongoing need for treatments that are more effective and safer than those currently available. Lactic acid bacteria (LAB) show beneficial effects in the context of several diseases, including CRC, and are generally regarded as safe. Here, we isolated a Lactobacillus rhamnosus (LR)-derived therapeutic protein, p8, which suppressed CRC proliferation. We found that p8 translocated specifically to the cytosol of DLD-1 cells. Moreover, p8 down-regulated expression of Cyclin B1 and Cdk1, both of which are required for cell cycle progression. We confirmed that p8 exerted strong anti-proliferative activity in a mouse CRC xenograft model. Intraperitoneal injection of recombinant p8 (r-p8) led to a significant reduction (up to 59%) in tumor mass when compared with controls. In recent years, bacterial drug delivery systems (DDSs) have proven to be effective therapeutic agents for acute colitis. Therefore, we aimed to use such systems, particularly LAB, to generate the valuable therapeutic proteins to treat CRC. To this end, we developed a gene expression cassette capable of inducing secretion of large amounts of p8 protein from Pediococcus pentosaceus SL4 (PP). We then confirmed that this protein (PP-p8) exerted anti-proliferative activity in a mouse CRC xenograft model. Oral administration of PP-p8 DDS led to a marked reduction in tumor mass (up to 64%) compared with controls. The PP-p8 DDS using LAB described herein has advantages over other therapeutics; these advantages include improved safety (the protein is a probiotic), cost-free purification, and specific targeting of CRC cells.

• Preventive Nutrition and Food Science
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• 제15권1호
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• pp.74-77
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• 2010

Antibiotic-resistant Staphylococcus aureus is beginning to pose a social issue. Thus, there is an urgent need for the development of effective anti-staphylococcal agents to eradicate antibiotic-resistant S. aureus in food systems and to treat the pathogen in clinical areas. To address this need, lactic acid bacteria (LAB) from kimchi were screened for the production of anti-staphylococcal bacteriocin. From this screening, a bacteriocin generated by the MK3 strain, which was identified by 16S rRNA gene sequence analysis as Enterococcus faecium, demonstrated antimicrobial activity against an S. aureus strain, and was designated enterocin MK3. Enterocin MK3 also demonstrated activity against other gram-positive bacteria, including several LAB and Listeria monocytogenes, but not gram-negative Escherichia coli. The molecular mass of enterocin MK3 was estimated as approximately 6.5 kDa on an SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) gel.

• Journal of Microbiology and Biotechnology
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• 제31권6호
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• pp.840-846
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• 2021

To improve the bile salt and acid tolerance of probiotics against gastrointestinal stresses, we investigated the effects of soybean lecithin and whey protein concentrate (WPC) 80 on the bile salt tolerance of Lacticaseibacillus paracasei L9 using a single-factor methodology, which was optimized using response surface methodology (RSM). The survival rate of L. paracasei L9 treated with 0.3% (w/v) bile salt for 2.5 h, and combined with soybean lecithin or WPC 80, was lower than 1%. After optimization, the survival rate of L. paracasei L9 incubated in 0.3% bile salt for 2.5 h reached 52.5% at a ratio of 0.74% soybean lecithin and 2.54% WPC 80. Moreover, this optimized method improved the survival rate of L. paracasei L9 in low pH condition and can be applied to other lactic acid bacteria (LAB) strains. Conclusively, the combination of soybean lecithin and WPC 80 significantly improved the bile salt and acid tolerance of LAB. Our study provides a novel approach for enhancing the gastrointestinal tolerance of LAB by combining food-derived components that have different properties.

• 대한수의학회지
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• 제55권2호
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• pp.81-88
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• 2015

This study was conducted to isolate lactic acid bacteria (LAB) from dog intestine and identify potential probiotic strains for canine use. One hundred and one LAB were isolated from feces of 20 healthy dogs. Acid, bile, and heat resistance along with adherence to Caco-2 cells and antimicrobial activity against pathogens were examined. To analyze immunomodulative effects, the production of nitric oxide (NO), TNF-${\alpha}$, and IL-$1{\beta}$ was measured using RAW 264.7 macrophages. Additionally, RAW BLUE cells were used to evaluate nuclear factor-${\kappa}B$ (NF-${\kappa}B$) generation. Ultimately, three strains were selected as canine probiotics and identified as Lactobacillus reuteri L10, Enterococcus faecium S33, and Bifidobacterium longum B3 by 16S rRNA sequence analysis. The L10 and S33 strains showed tolerance to pH 2.5 for 2 h, 1.0% Oxgall for 2 h, and $60^{\circ}C$ for 5 min. These strains also had strong antimicrobial activity against Escherichia coli KCTC 1682, Salmonella Enteritidis KCCM 12021, Staphylococcus aureus KCTC 1621, and Listeria monocytogenes KCTC 3569. All three strains exerted better immunomodulatory effects than Lactobacillus rhamnosus GG (LGG), a well-known commercial immunomodulatory strain, based on NO, NF-${\kappa}B$, IL-$1{\beta}$, and TNF-${\alpha}$ production. These results suggested that the three selected strains could serve as canine probiotics.