• Asian-Australasian Journal of Animal Sciences
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• v.23 no.6
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• pp.700-707
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• 2010

Effects of protease-resistant antimicrobial substances (PRA) produced by Lactobacillus plantarum and Leuconostoc citreum on rumen methanogenesis were examined using the in vitro continuous methane quantification system. Four different strains of lactic acid bacteria, i) Lactococcus lactis ATCC19435 (Control, non-antibacterial substances), ii) Lactococcus lactis NCIMB702054 (Nisin-Z), iii) Lactobacillus plantarum TUA1490L (PRA-1), and iv) Leuconostoc citreum JCM9698 (PRA-2) were individually cultured in GYEKP medium. An 80 ml aliquot of each supernatant was inoculated into phosphate-buffered rumen fluid. PRA-1 remarkably decreased cumulative methane production, though propionate, butyrate and ammonia N decreased. For PRA-2, there were no effects on $CH_4$ and $CO_2$ production and fermentation characteristics in mixed rumen cultures. The results suggested that PRA-1 reduced the number of methanogens or inhibited utilization of hydrogen in rumen fermentation.

• Food Science and Biotechnology
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• v.17 no.6
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• pp.1221-1227
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• 2008

The application of the cellulase gene (celA) as a selection marker of food-grade integration system was investigated in Lactobacillus (Lb.) casei, Lactococcus lactis, and Leuconostoc (Leu.) mesenteroides. The 6.0-kb vector pOC13 containing celA from Clostridium thermocellum with an integrase gene and a phage attachment site originating from bacteriophage A2 was used for site-specific recombination into chromosomal DNA of lactic acid bacteria (LAB). pOC13 was also equipped with a broad host range plus replication origin from the lactococcal plasmid pWV01, and a controllable promoter of nisA ($P_{nisA}$) for the production of foreign proteins. pOC13 was integrated successfully into Lb. casei EM116, and pOC13 integrants were easily detectable by the formation of halo zone on plates containing cellulose. Recombinant Lb. casei EM 116::pOC13 maintained these traits in the absence of selection pressure during 100 generations. pOC13 was integrated into the chromosome of L. lactis and Leu. mesenteroides, and celA acted as an efficient selection marker. These results show that celA can be used as a food-grade selection marker, and that the new integrative vector could be used for the production of foreign proteins in LAB.

• Journal of Ginseng Research
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• v.41 no.4
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• pp.524-530
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• 2017

Background: Panax ginseng is a physiologically active plant widely used in traditional medicine that is characterized by the presence of ginsenosides. Rb1, a major ginsenoside, is used as the starting material for producing ginsenoside derivatives with enhanced pharmaceutical potentials through chemical, enzymatic, or microbial transformation. Methods: To investigate the bioconversion of ginsenoside Rb1, we prepared kimchi originated bacterial strains Leuconostoc mensenteroides WiKim19, Pediococcus pentosaceus WiKim20, Lactobacillus brevis WiKim47, Leuconostoc lactis WiKim48, and Lactobacillus sakei WiKim49 and analyzed bioconversion products using LC-MS/MS mass spectrometer. Results: L. mesenteroides WiKim19 and Pediococcus pentosaceus WiKim20 converted ginsenoside Rb1 into the ginsenoside Rg3 approximately five times more than Lactobacillus brevis WiKim47, Leuconostoc lactis WiKim48, and Lactobacillus sakei WiKim49. L mesenteroides WIKim19 showed positive correlation with b-glucosidase activity and higher transformation ability of ginsenoside Rb1 into Rg3 than the other strains whereas, P. pentosaceus WiKim20 showed an elevated production of Rb3 even with lack of b-glucosidase activity but have the highest acidity among the five lactic acid bacteria (LAB). Conclusion: Ginsenoside Rg5 concentration of five LABs have ranged from ${\sim}2.6{\mu}g/mL$ to $6.5{\mu}g/mL$ and increased in accordance with the incubation periods. Our results indicate that the enzymatic activity along with acidic condition contribute to the production of minor ginsenoside from lactic acid bacteria.

• Journal of Microbiology and Biotechnology
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• v.21 no.2
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• pp.162-169
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• 2011

A dynamic model of lactic acid fermentation using Lactococcus lactis was constructed, and a metabolic flux analysis (MFA) and metabolic control analysis (MCA) were performed to reveal an intensive metabolic understanding of lactic acid bacteria (LAB). The parameter estimation was conducted with COPASI software to construct a more accurate metabolic model. The experimental data used in the parameter estimation were obtained from an LC-MS/MS analysis and time-course simulation study. The MFA results were a reasonable explanation of the experimental data. Through the parameter estimation, the metabolic system of lactic acid bacteria can be thoroughly understood through comparisons with the original parameters. The coefficients derived from the MCA indicated that the reaction rate of L-lactate dehydrogenase was activated by fructose 1,6-bisphosphate and pyruvate, and pyruvate appeared to be a stronger activator of L-lactate dehydrogenase than fructose 1,6-bisphosphate. Additionally, pyruvate acted as an inhibitor to pyruvate kinase and the phosphotransferase system. Glucose 6-phosphate and phosphoenolpyruvate showed activation effects on pyruvate kinase. Hexose transporter was the strongest effector on the flux through L-lactate dehydrogenase. The concentration control coefficient (CCC) showed similar results to the flux control coefficient (FCC).

• Journal of Dairy Science and Biotechnology
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• v.26 no.2
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• pp.31-37
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• 2008

One hundred one years have passed since Metchnikoff made his first scientific contribution to probiotics study. Intestinal lactic acid bacteria (LAB) for humans are closely associated with the host's health because LAB is an important biodefense factor in preventing colonization and subsequent proliferation of pathogenic bacteria in the intestine. A probiotic is recently defined as "live microorganisms that when administered in adequate amount confer a health benefit on the host". Some species of LAB have been claimed as probiotics, such as Lactobacillus acidophilus, L. casei, L. fermentum, L. plantarum, L. reuteri, and Lactococcus lactis. For understanding the general mechanism of probiotics, this paper would explore the early studies relating to probiotics and intestinal microbiota, and briefly introduce the Prolongation of Life written by Elie Metctmikoff.

• Korean Journal of Veterinary Service
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• v.29 no.3
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• pp.277-285
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• 2006

Plasmids are covalently closed circular molecules of DNA that are stably inherited and replicate somewhat independently of the bacterial chromosome. Genes carried on plasmids can mediate a wide variety of important functions, including antibiotics (R plasmids) and heavy metals resistance, toxins production, cell penetration, iron chelation, complement resistance, and metabolic characteristics such as sucrose and lactose fermentation. Fifty strains of lactobacilli were isolated from 26 staters and 29 fermented milk products. They were classified 27 strains as Lactobacillus paracasei subsp paracasei, 11 stains as Lactococcus lactis subsp cremoris, 6 strains as L delbrueckii subsp lactis, 4 strains as L acidophius, and 2 strains as L delbrueckii subsp bulgaricus. All of these strains were examined for drug resistance and transferability of R plasmids. All of the isolates were sensitive to Am, C, CF, E, NB, P, T, and Te. But resistant to SXT 94% (47 strains), K 66% (33 strains), S 56% (28 strains), ENR 50% (25 strains), NOR 38% (19 strains) CIP 38% (19 strains), GM 16% (8 strains), and N 14% (7 strains), in order. And 32 different resistant patterns were found. The most frequently encountered patterns were CIP-ENR-K-NOR-S-SXT (5 strains). In vitro R plasmids transfer experiment, 57 antibiotic resistant strains which were not transfer to the recipient 2 Escherichia coli strains by conjugation, These results indicate that Lactobacillus in internal trade market' stater recognize R factor but transmissible R plasmid is not existed.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.9
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• pp.1304-1312
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• 2013

The effects of storage period and aerobic deterioration on the bacterial community were examined in Italian ryegrass (IR), guinea grass (GG), and whole-crop maize (WM) silages. Direct-cut forages were stored in a laboratory silo for 3, 7, 14, 28, 56, and 120 d without any additives; live counts, content of fermentation products, and characteristics of the bacterial community were determined. 2,3-Butanediol, acetic acid, and lactic acid were the dominant fermentation products in the IR, GG, and WM silages, respectively. The acetic acid content increased as a result of prolonged ensiling, regardless of the type of silage crop, and the changes were distinctively visible from the beginning of GG ensiling. Pantoea agglomerans, Rahnella aquatilis, and Enterobacter sp. were the major bacteria in the IR silage, indicating that alcoholic fermentation may be due to the activity of enterobacteria. Staphylococcus sciuri and Bacillus pumilus were detected when IR silage was spoiled, whereas between aerobically stable and unstable silages, no differences were seen in the bacterial community at silo opening. Lactococcus lactis was a representative bacterium, although acetic acid was the major fermentation product in the GG silage. Lactobacillus plantarum, Lactobacillus brevis, and Morganella morganii were suggested to be associated with the increase in acetic acid due to prolonged storage. Enterobacter cloacae appeared when the GG silage was spoiled. In the WM silage, no distinctive changes due to prolonged ensiling were seen in the bacterial community. Throughout the ensiling, Weissella paramesenteroides, Weissella confusa, and Klebsiella pneumoniae were present in addition to L. plantarum, L. brevis, and L. lactis. Upon deterioration, Acetobacter pasteurianus, Klebsiella variicola, Enterobacter hormaechei, and Bacillus gibsonii were detected. These results demonstrate the diverse bacterial community that evolves during ensiling and aerobic spoilage of IR, GG, and WM silages.

• Biomolecules & Therapeutics
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• v.9 no.2
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• pp.79-87
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• 2001

Heat shock proteins serve as chaperone by preventing the aggregation of denatured proteins and promote survival of pathogens in harsh environments. In this study, heat shock gene encoding a 84-kDa (p84) protein, which is one of the three major heat shock proteins in S. pneumoniae, was cloned and characterized. PCR with a forward primer derived from N-terminal amino acid sequence of the p84 and a reverse primer derived from the conserved second ATP-binding region of Clp family was used for amplification of the gene encoding the p84 and subsequently the PCR product was used for sequence determination. Sequence analysis of the p84 gene demonstrated that it is a member of ClpL. The deduced amino acid sequence of pneumococcal ClpL shows homology with other members of the Clp family, and particularly, even in variable leader region, with bovine Clp-like protein and L. lactis ClpL. S. pneumoniae clpL is the smallest clop member (701 amono acids) containing the two conserved ATP-binding regions, and hydrophilic N-terminal variable region of pneu-mococcal Clp ATPase is much shorter than any known Clp ATPases. Histidine tagged ClpL was overexpressed and purified from E. coli. Immunoblot analysis employing antisera raised against pneumococcus p84 demonstrated no cross-reactivity with Clp analog in Eschericha coli, Staphylococcus aureus and human HeLa cells. Preimmunization of mice with ClpL extended mice life partially but did not protect them from death.

• Journal of Life Science
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• v.19 no.2
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• pp.277-283
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• 2009

Biogenic amines are generally formed through the decarboxylation of specific free amino acids by exogenous decarboxylases released by microbial species associated with the fish products and fermented feeds. This study was conducted to investigate the properties of e tuna waste regarding the control of degradation of biogenic amines (histamine, tyramine, tryptamine, putrescine, and cadaverine) that might be related with the anti-nutritional factor of the tuna waste that is used for manufacturing domestic fish meal. The values of pH and the salt content were 6.51, 3.35% in tuna waste and 5.58 and 5.83% in tuna fish meal, respectively. The strains and dominant bacteria tested in the tuna waste sample were 9.20, 9.29, 5.67, 7.82 and 7.58 log CFU/g of total bacteria, aerobic plate count (APC), total coliform (TC), Lactobacillus spp. and Bacillus spp., respectively. The main histamine forming-bacteria (HFB) in tuna waste were detected by silica gel thin-layer chromatography (TLC) and 7 histamine-forming bacterial species were isolated among microbes grown in selective medium. The histamine concentration was determined by detection of fluorescence of ο-phthaldialdehyde (OPA) derivatives using HPLC and the date were used to reconfirm the identities of the amine-producing bacteria. The 15 histamine- forming bacteria strains grown in trypicase soy broth (TSB) supplemented with 1% L-histidine (TSBH) were identified as Lactococcus(L.) lactis subsp. lactis, Klebsiella pneummonlae, L. garvieae 36, Vibrio olivaceus, Hafnia alvei and L. garvieae which were main dominant amine - producing strains, and Morganella morganii identified by 16S ribosomal RNA (rRNA) sequencing with PCR amplification. A Phylogenetic tree generated from the 16S rRNA sequencing data showed different phyletic lines that could be readily classified as biogenic amine forming gram-positive and negative bacteria.

• Korean Journal of Agricultural Science
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• v.48 no.2
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• pp.209-218
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• 2021

This study was carried out to investigate the effects of Bifidobacteria growth promoter BE0623 and a dietary fiber supplement, which included Bifidobacterium lactis BB12, Lactobacillus acidophilus, Streptococcus thermophilus, and Bifidobacterium lactis. In fermented milk containing BE0623, the viable cell count of Bifidobacteria significantly increased by about 45 to 75 times compared to the control, and the titratable acidity increased, whereas the pH decreased. All fractions obtained by isolating BE0623 had Bifidobacteria growth effect. Acacia dietary fiber is a pale yellow powder. It has a viscosity of 60 to 100 cPs and a pH between 4.1 and 5.0. Its general components are less than 10% moisture, more than 90% dietary fiber, and less than 4% ash. The optimal addition ratio of Bifidobacteria growth promoting material was determined to be 0.05%. The general components of the manufactured fermented milk were carbohydrate 17.85%, protein 3.63%, fat 3.00%, and dietary fiber 2.95%. During storage of the fermented milk for 24 days, its titratable acidity, viscosity, and sugar content all met the criteria. In addition, the viable cell counts of Bifidobacteria and lactic acid bacteria in the fermented milk were 1.7 × 10⁸ CFU·mL^-1 and 1.5 × 10⁷ CFU·mL^-1, respectively, and Escherichia coli was negative. There was no significant difference between the control group and the treatment group in the sensory evaluation of sweet, sour, weight, and flavor, and the preference for the treatment group was excellent. The acceptability of the fermented milk of the treated group according to the storage period was excellent in terms of color, flavor, and appearance.