• Food Science of Animal Resources
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• v.35 no.4
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• pp.551-556
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• 2015

The aim of this study was to evaluate the functional properties of lactic acid bacteria from various sources and to identify strains for use as probiotics. Ten Lactobacillus strains were selected and their properties such as bile tolerance, acid resistance, cholesterol assimilation activity, and adherence to HT-29 cells were assessed to determine their potential as probiotics. Lactobacillus sp. JNU 8829, L. casei MB3, L. sakei MA9, L. sakei CH8, and L. acidophilus M23 were found to show full tolerance to the 0.3% bile acid. All strains without L. acidophilus M23 were the most acid-tolerant strains. After incubating the strains at pH 2.5 for 2 h, their viability decreased by 3 Log cells. Some strains survived at pH 2.5 in the presence of pepsin and 0.3% bile acid. Lactobacillus sp. JNU 8829, L. acidophilus KU41, L. acidophilus M23, L. fermentum NS2, L. plantarum M13, and L. plantarum NS3 were found to reduce cholesterol levels by ＞50% in vitro. In the adhesion assay, Lactobacillus sp. JNU 8829, L. casei MB3, L. sakei MA9, and L. sakei CH8 showed higher adhesion activities after 2 h of co-incubation with the intestinal cells. The results of this comprehensive analysis shows that this new probiotic strain named, Lactobacillus sp. JNU 8829 could be a promising candidate for dairy products.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.1
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• pp.131-136
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• 2006

During lactic acid bacteria (LAB) transit through the gastrointestinal tract, ingested microorganisms were exposed to successive stress factors, including low pH in the human stomach and in bile acid. These stress factors can be used as criteria for the selection of a viable probiotic strain. Four such strains (Lactobacillus helveticus SGU 0011, Lactobacillus pentosus SGU 0010, Streptococcus thermophilus SGU 0021 and Lactobacillus casei SGU 0020) were isolated from raw milk. When the identified LAB were exposed to synthetic gastric juice, whereas L. casei SGU 0020 and S. thermophilus SGU 0021 exhibited a 0% survival rate, L. helveticus SGU 0011 and L. pentosus SGU 0010 exhibited 60% and 95% survival rates. L. casei SGU 0020 and S. thermophilus SGU 0021 could not be examined with regard to their tolerances to artificial bile juice, as they uniformly died upon exposure. However, L. helveticus SGU 0011 and L. pentosus SGU 0010 individually survived at rates of 39% and 93%. Also, all four of these strains were confirmed to be tolerant of ten different antibiotics.

• Food Science and Preservation
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• v.14 no.1
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• pp.87-93
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• 2007

This study investigated the antimicrobial effect of germinated acorn pollen solution on harmful food-borne microorganisms. The antimicrobial activity when 8% (w/v) acorn pollen in 10% (w/v) sugar solution was extracted at $30^{\circ}C$ for 4 days. The minimal inhibitory concentration of this germinated acorn pollen solution was $40\;{\mu}L/mL$ for Gram-positive bacteria and $30\;{\mu}L/mL$ for Gram-negative bacteria. Acetic and lactic acids were present at high levels in germinated acom pollen solution. As pollen germination releases heat, the antimicrobial activities are heat-stable. The activities are tolerant of low pH. In summary, acorn pollen germination solution showed active antibiosis and should be developed as a natural preservative material.

• Korean Journal of Food Science and Technology
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• v.26 no.2
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• pp.167-171
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• 1994

With a view to improving microbiological quality of spinach powder which is currently used for convenience food production, comparative efficacy of ethylene oxide(EO) fumigation and gamma irradiation was investigated by determining microbial populations and physicochemical quality for treated samples. Spinach powder was contaminated with various microorganisms ranging from $10^{2}/g\;to\;10^{4}/g$, which composed of thermophiles, acid tolerant bacteria, fungi, coliforms, etc. Microorganisms contaminated were destroyed up to undetected levels by gamma irradiation at below 7 kGy. showing the radiosensitivity $D_{10}$ 2.93 kGy on total aerobic bacteria. Ethylene oxide fumigation, however. was found unsatisfactory for physicochemical quality as well as microbial decontamination of the sample. It has been generally observed that influence of optimum-dose range of irradiation on the physicochemical qualities was insignificant, which was proved in the organoleptic evaluations on the stored sample.

• Microbiology and Biotechnology Letters
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• v.41 no.1
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• pp.119-127
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• 2013

Twenty-three strains of Leuconostoc species and 45 strains of Weissella species inhibiting the growth of Lactobacillus sakei, one of the most populous lactic acid bacteria in over-ripened kimchi, were isolated from kimchi in our previous study. Among these hetero-fermentative 68 strains, Leuconostoc mesenteroides CK0128, Weissella cibaria CK0633, and W. cibaria KK0797 exhibited a relatively high survival rate in MRS medium, which was adjusted to pH 4.3 using an acid mixture consisting of acetic and lactic acids, and produced a large amount of exopolysaccharides. The culture supernatants of 3 strains were fractionated by a molecular weight cutter and lyophilized. The fractions with a molecular weight smaller than 3,000 Da showed antagonistic activity against Staphylococcus aureus and Lb. sakei. The anti-bacterial substances were very stable to heat treatments ($121^{\circ}C$, 15 min) and active at acidic conditions below pH 5. ${\alpha}$-Amylase, lipase, and proteolytic enzymes (proteinase K and pepsin) did not affect their activities. These non-proteinaceous anti-bacterial substances inhibited the growth of several food pathogens.

• Journal of Microbiology and Biotechnology
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• v.28 no.7
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• pp.1156-1167
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• 2018

The aim of this study was to isolate and characterize lead (Pb)-solubilizing bacteria from heavy metal-contaminated mine soils and to evaluate their inoculation effects on the growth and Pb absorption of Brassica juncea. The isolates were also evaluated for their plant growth-promoting characteristics as well as heavy metal and salt tolerance. A total of 171 Pb-tolerant isolates were identified, of which only 15 bacterial strains were able to produce clear haloes in solid medium containing PbO or $PbCO_3$, indicating Pb solubilization. All of these 15 strains were also able to dissolve the Pb minerals in a liquid medium, which was accompanied by significant decreases in pH values of the medium. Based on 16S rRNA gene sequence analysis, the Pb-solubilizing strains belonged to genera Bacillus, Paenibacillus, Brevibacterium, and Staphylococcus. A majority of the Pb-solubilizing strains were able to produce indole acetic acid and siderophores to different extents. Two of the Pb-solubilizing isolates were able to solubilize inorganic phosphate as well. Some of the strains displayed tolerance to different heavy metals and to salt stress and were able to grow in a wide pH range. Inoculation with two selected Pb-solubilizing and plant growth-promoting strains, (i.e., Brevibacterium frigoritolerans YSP40 and Bacillus paralicheniformis YSP151) and their consortium enhanced the growth and Pb uptake of B. juncea plants grown in a metal-contaminated soil. The bacterial strains isolated in this study are promising candidates to develop novel microbe-assisted phytoremediation strategies for metal-contaminated soils.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.1
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• pp.89-95
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• 2013

Biological and functional characteristics of lactic acid bacteria (LAB) were investigated in mustard stem/leaf kimchi (MK), cabbage kimchi (CK), young radish kimchi (YRK), and cubed radish kimchi (CRK). LAB of young radish kimchi were mainly composed of bacilli in contrast to the other kimchi. 89.2% LAB isolated from all kimchi harbored plasmids. However, LAB had an average of $4.1{\pm}0.5$ plasmid bands in YRK, more than MK, CK, and CRK. Exopolysaccharides were produced by 10.9~11.1% of LAB, and were especially by LAB isolated from radish kimchi. A significant percentage of LAB (69.5%) had antibacterial activity against one sensitive strain or more. LAB from CK, YRK and CRK had antimicrobial activities against Bacillus sp., Listeria monocytogenes, and Salmonella Typhimurium, while the LAB from MK had activities against Vibrio parahaemolyticus higher than those from the other kimchi. In YRK and CRK, acid-tolerant LAB were twice as prevalent as those in MK and CK. Bile-tolerant LAB isolated from CRK were more prevalent than other kimchi. When $10^8$ CFU of LAB were added to Caco-2 cells, 12.1% of LAB isolated from all kimchi showed similar adherent activity to Lactobacillus rhamnosus GG. LAB of MK particularly adhered to Caco-2 cells, 2.0~4.1 fold higher than LAB in the other kimchi. From these results, biological and functional characteristics of LAB varied according to the type of kimchi and LAB existing in kimchi were limited to their respective species.

• Korean Journal of Environmental Agriculture
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• v.16 no.4
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• pp.311-319
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• 1997

Heavy metal-tolerant microorganisms, such as Pseudomonas putida, P. aeruginosa, P. chlororaphis and P. stutzeri which possessed the ability to accumulate cadmium, lead, zinc and copper, respectively, were isolated from industrial wastewaters and mine wasewaters polluted with various heavy metals. Metal binding sites in the cells were investigated by extracting the components of the cells through pretreatments with hot water, acid, alkli, chloroform-methanol or chloroform-methanol/concentrated alkali. The heavy metal accumulation was drastically decreased by pretreatment with alkali or chloroform-methanol/concentrated alkali, but the heavy metal accumulation was not changed by pretreatment with chloroform-methanol. The amount of heavy metal accumulation was remarkably decreased by decreasing crude protein remaining in the cell. These results suggested that proteins of cell components played an important role on the heavy metal accumulation.

• Journal of Life Science
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• v.24 no.1
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• pp.46-53
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• 2014

Lactobacillus sakei 383, which showed the highest GABA content in fermented soycurd, survived in artificial gastric fluid (pH 3.0) up to 3 h, and the survival rate was 88%. L. sakei 383 was tolerant to bile juice during incubation in MRS broth with 0.3% oxgall, and the survival rate was 99%. The survival ratio of L. sakei 383 was high in media containing less than 6% NaCl. L. sakei 383 produced an antibacterial substance against various pathogens, including Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus, Escherichia coli, and Salmonella typhi. The quality characteristics of soycurd fermented with L. sakei 383 were measured during the fermentation period. The viable cell number reached a peak ($10^{11}CFU/ml$) 36 h after fermentation and then slowly decreased. According to the fermentation time of L. sakei 383, the acidity of soycurd increased and the pH decreased until 12 h, and they were maintained thereafter. The moisture, crude ash, crude protein, crude fat, and crude fiber content was 94.88, 0.22, 2.38, 1.16, and 0.03%, respectively. The content of total and reducing sugar was comparatively higher in the soycurd fermented with L. sakei 383 than in nonfermented soycurd. The essential and nonessential amino acid content was 11.2 and 38.65 mg/100 g.

• Microbiology and Biotechnology Letters
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• v.28 no.5
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• pp.279-284
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• 2000

This study was per-formed to screen lactic acid bacteria poultry for the probiotic use. Among the previously obtained acid tolerant, 139 strains, 111 strains were selected with MRS medium containing 0.3% oxgall. 34 strains of 111 was re-selected by Gram-staining and acid producing ability. These strains was identified by MIDI Sherlock Microbial Identification System. Among the identified 34 strains Lactobacillus fermenum YL-3 was selected for the final pro-biotic use because of the good growth and high survival rate at pH 2.0. 60%, 50% and 40% cells of Lactobacillus fermentum YL-3 survived at pH 3.0, 2.5 and 2.0, respectively. More than $10^{7}$ / CFU/ml survived when exposed with the number of $10^{8}$ CFU/ml at pH 2.0 after 12 hr. L.fermenum YL-3 maintained growth in MRS broth containing 0.3, 0.5, 1.0 and 2.0% oxgall for 24 hr. L.fermenum YL-3 showed an inhibitory effect against pathogenic strains of Sal. enteritidis and E. coli O157:H7. In mixed culture with L.fermenum YL-3 Sal. enteritidis lost ability com-pletely in 15 hrs and E. coil O157:H7 in 16 hrs.