• Journal of Dairy Science and Biotechnology
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• v.41 no.4
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• pp.211-218
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• 2023

This study aimed to identify lactic acid bacteria isolated from eight fermented milk products in Iran. We enumerated Lactobacillus species using De Man-Rogosa-Sharpe (MRS)-maltose and MRS agar with pH adjusted to 5.2, as well as assessment at 37℃ for 48 hr, studied Streptococcus spp. using M17 agar at 43℃ for 24 hr, and assessed Bifidobacterium species using nalidixic acid, paromomycin sulfate, neomycin sulfate, and lithium chloride (BL-NPNL) agar at 37℃ for 48 hr. The total viable Streptococcus spp. cell in fermented milk varied at 4.73-8.83 log CFU/mL. However, Bifidobacterium spp. were not detected in any of the tested samples. Lactobacilli were not detected in four of the eight samples, and viable Lactobacilli cells in the remaining four samples ranged 2.48-3.85 log CFU/mL. The pH of the tested samples ranged 3.53-4.19, and soluble solids (Brix measurement) ranged 7.5%-17.9%. A total of 130 isolates of gram-positive catalase-positive bacteria were characterized at the species level using 16S rRNA sequencing. Sequence analysis identified six species: Streptococcus thermophilus, Lactobacillus delbrueckii subsp. sunkii, Lactobacillus delbrueckii subsp. indicus, Lactiplantibacillus plantarum, Lacticaseibacillus rhamnosus, and Levilactobacillus brevis.

• Journal of Microbiology
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• v.43 no.3
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• pp.251-256
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• 2005

In this study, we assessed the susceptibility of 12 Lactobacillus strains, all of which had been isolated from the gastrointestinal tracts of chicken, to three antibiotics (chloramphenicol, erythromycin and tetracycline) used commonly as selective markers in transformation studies of lactic acid bacteria. Among these strains, $17\%,\;58\%,\;and\;25\%$ were found to exhibit a high degree of resistance to $200\;{\mu}g/ml$ of tetracycline, erythromycin, and chloramphenicol, respectively. Seven of the 12 Lactobacillus strains exhibiting resistance to at least $50\;{\mu}g/ml$ of chloramphenicol or erythromycin, and five strains exhibiting resistance to at least $50\;{\mu}g/ml$ of tetracycline, were subsequently subjected to plasmid curing with chemical curing agents, such as novobiocin, acriflavin, SDS, and ethidium bromide. In no cases did the antibiotic resistance of these strains prove to be curable, with the exception of the erythromycin resistance exhibited by five Lactobacillus strains (L. acidophilus I16 and I26, L. fermentum I24 and C17, and L. brevis C10). Analysis of the plasmid profiles of these five cured derivatives revealed that all of the derivatives, except for L. acidophilus I16, possessed profiles similar to those of wild-type strains. The curing of L. acidophilus I16 was accompanied by the loss of 4.4 kb, 6.1 kb, and 11.5 kb plasmids.

• Journal of Life Science
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• v.30 no.7
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• pp.581-591
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• 2020

This study investigated the probiotic properties and physiological activities of Korean fermented foods such as sikhae, young radish kimchi, and bean-curd dregs. Among the isolated lactic acid bacteria, Pediococcus inopinatus BZ4, Lactobacillus plantarum SH1, Lactobacillus brevis SH14, Pediococcus pentosaceus YMT1, and Leuconostoc mesenteroides YMT6 demonstrated a greater than 60% survival rate at pH 2.5, along with an excellent survival rate even at 0.3% bile acid. These five bacteria showed strong flocculation ability in autoaggregation and coaggregation tests, indirectly clustering useful micro-organisms and inhibiting the attachment of pathogenic bacteria. In a cell surface hydrophobicity test, these bacteria showed adhesion to three solvents (ethyl acetate, chloroform, and xylene) and high hydrophobicity, thereby indicating excellent indirect cell adhesion to intestinal cells. The cell-free supernatants and intracellular extracts of the five lactic acid bacteria showed antioxidative activity in the form of 2,2-Diphenyl-1-picrylhydrazyl and 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging ability and lipid peroxidation inhibition. Antimicrobial activities were also observed in four pathogenic bacteria, namely E. coli KCTC 2571, H. pylori HPKCTC B0150, L. monocytogenes KCTC 13064, and S. aureus KCTC 1916. These results demonstrate that these five lactic acid bacteria could be used as probiotics with antioxidant and antimicrobial properties.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.8
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• pp.973-978
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• 2006

This study was conducted to investigate the solubility, antioxidative and antimicrobial activity of the freeze dried chitosan-ascorbate (CAs) and chitosan-acetate (CAc). In the results of solubility, CAs was soluble over 0.5% in distilled water, vinegar, green tea, soju (distilled liquor), beer and red wine, while it was not soluble in soy sauce, soy milk, milk, orange juice, coffee, sesame oil, soy milk and soybean oil. The solubility of CAc in the liquid foods was similar to those of CAs, but it was soluble less than 0.1% in beer, and formed curd in red wine. Electron donating activity, antioxidative activity and SOD activity of CAs were 48.2, 90.6 and 67.5%, respectively, while the activities of the CAc were 0, 40.0 and 10.0%, respectively. The minimal inhibitory concentrations of CAs and CAc were $200\;{\mu}g/disc$ against Bacillus circulans, Bacillus brevis, Bacillus licheniformis, Bacillus arabitane and Bacillus sterothermophillus, $400\;{\mu}g/disc$ against Escherichia coli O157, Listeria monocytogenous, Bacillus cereus and Bacillus subtilis. There was no significant difference in Hunter's L* value between CAs and CAc $(81.95{\sim}82.97)$, but Hunter's a* and b* values of the CAs was higher than those of CAc. While sour and bitter tastes of CAs were lower than those of CAc, there was no significant difference in astringent taste. From these results, it suggested that CAs has more extensive utility in liquid foods with antimicrobial and antioxidant activity as well as sensory quality compared to CAc.

• Journal of The Korean Society of Grassland and Forage Science
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• v.42 no.2
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• pp.96-102
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• 2022

The present study investigated effects of microbial additives and silo density on chemical compositions, fermentation indices, and aerobic stability of whole crop rice (WCR) silage. The WCR ("Youngwoo") was harvested at 49.7% dry matter (DM), and ensiled into 500 kg bale silo with two different compaction pressures at 430 kgf (kilogram-force)/cm² (LOW) and 760 kgf/cm² (HIGH) densities. All WCR forage were applied distilled water (CON) or mixed inoculants (Lactobacillus brevis 5M2 and Lactobacillus buchneri 6M1) with 1:1 ratio at 1x105 colony forming unit/g (INO). The concentrations of DM, crude protein, ether extract, crude ash, neutral detergent fiber, and acid detergent fiber of whole crop rice before ensiling were 49.7, 9.59, 2.85, 6.74, 39.7, and 21.9%, respectively. Microbial additives and silo density did not affect the chemical compositions of WCR silage (p>0.05). The INO silages had lower lactate (p<0.001), but higher propionate (p<0.001). The LOW silages had higher lactate (p=0.004). The INO silages had higher yeast count (p<0.001) and aerobic stability (p<0.001). However, microbial counts and aerobic stability were not affected by silo density. Therefore, this study concluded that fermentation quality of WCR silage improved by microbial additives, but no effects by silo density.

• Korean Chemical Engineering Research
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• v.56 no.4
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• pp.453-460
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• 2018

Owing to rising oil prices and anthropogenic global warming, focused attempts are being made toward production of industrially important compounds by using renewable biomass. In this context, algal biomass as third-generation biomass is important because it doesn't compatible with food resource, has high yield, and helps abate greenhouse gases. Here, we investigate whether Undaria has the highest sugar content, which would make it the most suitable biomass for lactic acid production among the four algal biomasses tested. For effective pretreatment of Undaria, the response surface methodology was used. The amount of solid loaded and catalyst concentration were related to the extraction rate of total sugar. Lactic acid was produced by pretreatment of Undaria by using four Lactobacilli, and L. alimentarius and L. brevis were found to be suitable for lactic acid production.

• Journal of Dairy Science and Biotechnology
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• v.35 no.2
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• pp.93-97
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• 2017

Linum usitatissimum L. (flaxseed) is emerging as an important functional food ingredient because of its rich contents, namely, ${\alpha}$-linolenic acid (ALA, omega-3 fatty acid), lignans, and fiber, which are potentially beneficial for human health. Furthermore, flax or flaxseed oil has also been incorporated as a functional food ingredient into various foods such as milk, dairy products, and meat products. Flaxseed is known to possess antimicrobial activity in vitro and in vivo, but its growth-stimulating effect on lactic acid bacteria is not clear. Hence, the objective of this study was to determine whether crude flaxseed extract stimulated the growth kefir-isolated lactic acid bacteria in vitro. The result of this study showed that Lactobacillus kefiranofaciens DN1, Lactobacillus brevis KCTC3102, Lactobacillus bulgaricus KCTC3635, and Lactobacillus plantarum KCTC3105 treated with $100{\mu}L$ of crude flaxseed extract showed significantly higher growth than the control treated with $100{\mu}L$ of water (p<0.05). Based on the results of this study, crude flaxseed extract could be used as a growth stimulator for lactic acid bacteria in various food applications, including production of milk and dairy products.

• Microbiology and Biotechnology Letters
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• v.37 no.4
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• pp.389-398
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• 2009

Development of expression vectors is important for the basic and applied researches on kimchi LAB (lactic acid bacteria). An expression vector, pSJE6c was constructed by inserting P6C promoter sequence from Lactococcus lactis into pSJE, a shuttle vector for E. coli and Leuconostoc species. To test the efficiency of pSJE6c, aga ($\alpha$-galactosidase) and lacZ ($\beta$-galactosidase) genes were expressed in Lactobacillus brevis 2.14. Compared to the pSJE, expression levels of both genes were increased, indicating P6C promoter was better than indigenous promoters. Enzyme activities of L. brevis cells harboring pSJE6caga (pSJE6c with aga) or pSJE6Z (pSJE6c with lacZ) were 1.5-2 fold higher than those with pSJEaga (pSJE with aga) or pSJEZ (pSJE with lacZ). More RNA transcripts were detected in cells harboring pSJE6c based recombinant plasmid. The results indicated that heterologous gene expressions in kimchi LAB could be improved significantly by use of efficient expression vectors.

• Preventive Nutrition and Food Science
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• v.15 no.2
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• pp.105-112
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• 2010

Thirty-four strains of Lactobacillus species were isolated from soil and eight of these isolates (M1-4 and P1-4) were capable of growing on red ginseng agar. The M1 and P2 strains were determined to be L. plantarum and other strains (M2, M3, M4, P1, P3 and P4) were determined to be L. brevis. Fermentation of red ginseng extract (RGE) with strains M1, M2, P2 and P4 resulted in a low level of total carbohydrate content (174.3, 170.0, 158.8 and 164.8 mg/mL, respectively). RGE fermented by M3 showed a higher level of uronic acid than the control. The polyphenol levels in RGE fermented by M1, P1 and P2 (964.9, 941.7 and $965.3\;{\mu}g/mL$, respectively) were higher than the control ($936.8\;{\mu}g/mL$). Total saponin contents in fermented RGE (except M1) were higher than the control. RGE fermented by M2 and M3 had the highest levels of total ginsenosides (31.7 and 32.7 mg/mL, respectively). The levels of the ginsenoside Rg3 increased from 2.6 mg/mL (control) to 3.0 mg/mL (M2) or 3.1 mg/mL (M3). RGE fermented by M2 and M3 also had the highest levels of Rg5+Rk1 (7.7 and 8.3 mg/mL, respectively). Metabolite contents of ginsenoside (sum of CK, Rh1, Rg5, Rk1, Rg3 and Rg2) of M2 (13.0 mg/mL) and M3 (13.9 mg/mL) were also at a high level among the fermented RGE. Protopanaxadiol and protopanaxatriol content of ginsenoside of M2 (10.9 and 5.4 mg/mL, respectively) and M3 (11.0 and 5.7 mg/mL, respectively) were at higher levels than other fermented RGE.

• Korean Journal of Food Science and Technology
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• v.49 no.4
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• pp.459-461
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• 2017

This study investigated the screening and optimization of nitrite production from fermented spinach extract using different lactic acid bacteria, fermentation temperature, and time. Spinach extract was fermented using various lactic acid bacteria at 24, 30, and $36^{\circ}C$ for 6, 12, 18, 24, 36, 48, 72, and 96 h in the presence of different carbohydrates (glucose, sucrose, fructose, and lactose). Lactobacillus farciminis (KCTC 3618) produced the highest amount of nitrite using fermented spinach extract at $30^{\circ}C$ for 28 h compared to Staphylococcus carnosus, L. coryniformis (KCTC 3167), L. fructosus (KCTC 3544), L. reuteri (KCTC 3677), L. amylophilus (KCTC 3160), L. hilgardii (KCTC 3500), L. delbrueckii (KCTC 1058), L. fermentum (KCTC 3112), L. plantarum (KCTC 3104), and L. brevis (KCTC 3498). Comparison of the yield at different fermentation temperatures showed that the highest amount of nitrite was produced using fermented spinach extract at $30^{\circ}C$. Similarly, maximum nitrite yield was observed after 36 h fermentationin in the presence of sucrose. Therefore, maximum nitrite production was observed upon L. farciminis-mediated fermentation of spinach extractat $30^{\circ}C$ for 36 h in the presence of sucrose.