• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.522-529
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• 2019

A Bacillus strain, SJ4, exhibiting strong fibrinolytic activity was isolated from saeu (shrimp, Acetes chinensis) jeotgal, a Korean traditional fermented food and was identified as B. subtilis. The B. subtilis SJ4 strain can grow at a NaCl concentration of up to 15% (w/v). The fibrinolytic activity of B. subtilis SJ4 (152.0 U/ml) cultured in Luria-Bertani (LB) broth for 48 h at 37℃ with aeration was higher than that of B. subtilis SJ4 cultured in TSB (124.5 U/ml) under same culture conditions. The major proteins in the LB culture supernatant of B. subtilis SJ4 were analyzed by SDS-PAGE, which revealed three major bands (23, 25, and 28 kDa). The band (23 kDa) with strong fibrinolytic activity, analyzed on fibrin zymogram, was observed at 60-96 h of cultivation. The aprESJ4 gene encoding the major fibrinolytic enzyme, AprESJ4, was cloned by PCR. The aprESJ4 gene sequence exhibited high similarities with the fibrinolytic gene sequences of other Bacillus species. The amino acid sequence of AprESJ4 exhibited 98.9 and 98.4% similarity with subtilisin NAT and AprE2 of B. subtilis, respectively. Hence, B. subtilis SJ4 can be a potential starter culture for jeotgal products.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.6
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• pp.1045-1051
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• 2021

Eighty-nine different types of commercially salt-fermented fishery products comprising various raw materials were analyzed for total aerobic bacteria, number of coliform bacteria, fecal coliform, and Escherichia coli. The food-poisoning bacterial content of the samples was investigated using next-generation sequencing. The mean mass of total aerobic bacteria in Jeotgal was 6-1.8×10⁹ CFU/g, and that in Aekjeot and Sikhae was 4-2.2×10⁵ CFU/mL and 1.9×10⁵-8.4×10⁸ CFU/g, respectively. Coliform bacteria were detected in 9 (28.1%) of 32 Jeotgal samples; 15 (46.8%) of 32 seasonal Jeotgal samples; and in 5 (55.5%) of 9 Sikhae samples. Fecal coliform and E. coli were not detected in 86 of the 89 samples. Yersinia enterocolitica was detected only in Galchi jeot (salt-fermented hairtail) (1 type) and not in other Jeotgal samples. These results contribute to our knowledge regarding the bacterial stability of salt-fermented fishery products.

• Microbiology and Biotechnology Letters
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• v.46 no.4
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• pp.313-319
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• 2018

Halophilic lactic acid bacteria (LAB) were isolated from myeolchi-jeotgal (23% NaCl, w/v) fermented in jangdok (Korean earthenware) located outside a house. They were identified as Tetragenococcus halophilus by 16S rRNA and recA gene sequencing. Four T. halophilus isolates showing high protease activities were selected for further studies. Four strains grew well, reaching $OD_{600}$ values of 0.75-0.92 at 18% NaCl content (w/v) and 0.28-0.44 at 23% salt. They showed rapid growth, attaining $OD_{600}$ values of 1.1-1.2 at $20-30^{\circ}C$, but did not grow at $4^{\circ}C$. At $15^{\circ}C$, the highest $OD_{600}$ values, which exceeded 0.6, were observed at 20 days, and were higher than those of cultures at $37^{\circ}C$ and $42^{\circ}C$ (approximately 0.5). Four isolates grew best in broth where the initial pH was adjusted to 8 and did not grow at $pH{\leq}4$. T. halophilus BS2-36 showed the highest survival ratio of 18.7% after 2 hours of exposure at pH 3. BS2-36 showed the highest survival ratio (1.29%) in presence of 0.3% bile salts. T. halophilus BS2-36 seems a promising candidate as a starter for jeotgal and other fermented foods with high salinities.

• Journal of Microbiology and Biotechnology
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• v.29 no.3
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• pp.347-356
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• 2019

Bacillus sp. BS2 showing strong fibrinolytic activity was isolated from sea squirt (munggae) jeotgal, a traditional Korean fermented seafood. BS2 was identified as B. velezensis by molecular biological methods. B. velezensis BS2 grows well at 15% NaCl and at $10^{\circ}C$. When B. velezensis BS2 was cultivated in TSB broth for 96 h at $37^{\circ}C$, the culture showed the highest fibrinolytic activity ($131.15mU/{\mu}l$) at 96 h. Three bands of 27, 35 and 60 kDa were observed from culture supernatant by SDS-PAGE, and fibrin zymography showed that the major fibrinolytic protein was the 27 kDa band. The gene (aprEBS2) encoding the major fibrinolytic protein was cloned, and overexpressed in heterologous hosts, B. subtilis WB600 and E. coli BL21 (DE3). B. subtilis transformant showed 1.5-fold higher fibrinolytic activity than B. velezensis BS2. Overproduced AprEBS2 in E. coli was purified by affinity chromatography. The optimum pH and temperature were pH 8.0 and $37^{\circ}C$, respectively. $K_m$ and $V_{max}$ were 0.15 mM and $39.68{\mu}M/l/min$, respectively, when N-succinyl-Ala-Ala-Pro-Phe-pNA was used as the substrate. AprEBS2 has strong ${\alpha}$-fibrinogenase and moderate ${\beta}$-fibrinogenase activity. Considering its high fibrinolytic activity, significant salt tolerance, and ability to grow at $10^{\circ}C$, B. velezensis BS2 can be used as a starter for jeotgal.

• Food Science of Animal Resources
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• v.34 no.1
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• pp.65-72
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• 2014

This study is executed to develop probiotics which produce S-adenosyl-L-methionine (SAM), a methyl group donor of the 5-methyltetrahydrofolate methylation reaction within the animal cell. SAM is an essential substance for the synthesis, activation, and metabolism of hormones, neurotransmitters, nucleic acids, phospholipids, and cell membranes of animals. The SAM is also known as a nutritional supplement to improve brain functions of the human. In this study, the SAM-producing strains are identified in 18 types of salted fish, and then, the strains with excellent SAM productions are being identified, with 1 strain in the Enterococcus genus and 9 strains in the Bacillus genus. Strains with a large amount of SAM production include the lactic acid bacteria such as En. faecium and En. durans, En. sanguinicola, as well as various strains in the Bacillus genus. The SAM-overproducing strains show antibacterial activities with certain harmful microbes in addition to the weak acid resistances and strong bile resistances, indicating characteristics of probiotics. It is possible that the jeotgal-originated beneficial strains with overproducing SAM can be commercially utilized in order to manufacture SAM enriched foods.

• Microbiology and Biotechnology Letters
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• v.43 no.1
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• pp.84-90
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• 2015

Seventeen ampicillin-sensitive coagulase-negative staphylococci (CNS) isolates identified in jeotgal were subjected to assessments for antibiotic susceptibility and safety hazards. Fifteen of the 17 CNS strains exhibited phenotypic resistances to at least one antibiotic, and their prevailing resistance was to penicillin G. The dfrA gene for trimethoprim and tetK for tetracycline were amplified by PCR from the two strains, respectively. α-Hemolytic activity was not detected from the 17 strains, while five strains presented δ-hemolytic activity. Among the five strains, two strains exhibited β-hemolytic activity. Biofilm was formed from twelve strains. All of the tested phenotypic characteristics were expressed in a strain-specific manner.

• Food Science and Biotechnology
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• v.17 no.4
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• pp.857-860
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• 2008

S-Adenosyl-L-methionine (SAM) is a bioactive material used in the treatment of depression, osteoarthritis, and liver disease. To obtain lactic acid bacteria (LAB) producing high concentrations of SAM, LAB were isolated from commercial kimchi and from prepared kimchi products that contained shrimp jeotgal (fermented salty seafood) or sand lance jeotgal or that were fermented at 5 or $10^{\circ}C$, respectively, when pH was 4.2 to 4.8 and titratable acidity 0.6 to 0.9. Among the 179 LAB strains isolated from the fermented kimchi products, the genus Leuconostoc produced the highest intracellular level of SAM (1.58 mM) and Lactobacillus produced the second highest level (up to 1.47 mM) in the strain culture. This is the first study to quantify SAM in LAB isolated from fermented kimchi prepared by a general kimchi recipe. Ultimately, the selected strains (Leuconostoc mesentroides subsp. mesenteroides/dextranicum KSK417, L. mesentroides subsp. mesenteroides/dextranicum KJM401, and Lactobacillus bifermentans QMW327) could be useful as starters to manufacture fermented foods containing high levels of SAM.

• Microbiology and Biotechnology Letters
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• v.49 no.1
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• pp.9-17
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• 2021

A γ-aminobutyric acid (GABA)-producing microorganism was isolated from galchi (hairtail fish, Trichiurus lepturus) jeotgal, a Korean salted and fermented seafood. The G144 isolate produced GABA excessively when incubated in MRS broth containing monosodium glutamate (MSG, 3%, w/v). G144 was identified as Lactobacillus brevis through 16S rRNA and recA gene sequencing. gadB and gadC encoding glutamate decarboxylase (GAD) and glutamate/GABA antiporter, respectively, were cloned and gadB was located downstream of gadC. The operon structure of gadCB was confirmed by reverse transcription (RT)-polymerase chain reaction. gadB was overexpressed in Escherichia coli and recombinant GAD was purified and its size was 54.4 kDa as evidenced by SDS-PAGE results. Maximum GAD activity was observed at pH 5.0 and 40℃ and the activity was dependent on pyridoxal 5'-phophate. The K_m and V_max of GAD were 8.6 mM and 0.01 mM/min, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.2
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• pp.271-276
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• 1997

The study was attempted to detemine the ratio of stomach and intestine to viscera gathered on catching vessels, the critical level of VBN content as a freshness quality of viscera of Alaska pollack for raw materials of Changran-jeotgal. It also examined the changes of VBN values, pH and viable tell counts during the fermentation. Then sensory evaluation of the fermented products, Changran-jeotgal, was done according to the freshness of raw materials used. The ratio of stomach and intestine to the gathered viscera on the vessel was about $72\%$, while that of round state of Alaska pollack was about $18\%$. There was no significant relationship in VBN content between fish muscle and viscera. It suggests that VBN content is not a reasonable freshness criteria in viscera but in fish muscle. However, if we use the VBN content as a freshness criteria of viscera for raw materials of Changran-jeotgal, less than $70mg\%$ of VBN value could be recommended. According to the experimental results, the product yields and sensory evaluation scores were no good not only for economical evaluation but also for consumption.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.1
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• pp.15-20
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• 2002

Quality variation of plastic pouch packing of Changran-Jeotgal produced by improved process and conventional process were investigated during storage at 10, 20 and $30^{\circ}C$, respectively. The kind of plastic pouch used in this study were polyethylene/nylon/linear low density polyethylene (PE/Ny), polyethylene terephthalatefpolyethyleneflinear low density polyethylene (PET) and low density polyethylene (PE). In the higher storage temperature, the faster increase of$ CO_2$, concentration and volume of pouch packing in all kinds of pouch. However, the highest value of pH, L-value, volatile basic nitrogen (VBN) and viable cell counts were shown in PE, the next was PET and PE/Ny, Overall, Changran-Jeotgal produced by improved process showed a little change of physical and chemical characteristics than conventional process. From above results, relationship between quality parameters were predicted pH, L-value, VBN and sensory score were highly correlated, therefore, these parameters is expected to uses as shelf-life indicated elements in cease of plastic pouch packaging.