• Journal of Life Science
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• v.33 no.3
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• pp.260-267
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• 2023

Helicobacter pylori infects the mucosa, induces chronic inflammation and ulcers, and is known as a biological carcinogen. Antibiotics are used as therapeutic agents for H. pylori, but there are problems such as resistance. Thus, research is being conducted on the use of lactic acid bacteria (LAB) as an alternative therapeutic agent. There have been many studies on LAB related to kimchi. However, studies related to Gajami Sikhae, a traditional fermented seafood in Korea, are insufficient. In this study, we investigated the inhibitory effect of LAB isolated from Gajami Sikhae on H. pylori and its use as a probiotic. Forty species of LAB isolated from Gajami Sikhae were identified as Lactobacillus plantarum, Lactobacillus brevis, Leuconostoc mesenteroides, and Weisella paramesenteroides, and 10 strains of 40 species were selected through liquid inhibition assay of H. pylori. The selected LAB supernatant at 1%, 5%, and 10% had a growth inhibitory effect on H. pylori 52, 51, e-53, and 309. The adjusted pH of 7.0 was used for the LAB culture supernatant, in reference to a study that the growth of H. pylori is affected by acid. All 10 strains of LAB at 5% and 10% concentration suppressed the growth of H. pylori 52, and 7 strains of LAB at 10% concentration suppressed the growth of H. pylori e-53. LAB also had the effect of suppressing the activity of urease. Finally, LAB isolated from Gajami Sikhae is expected to be useful for eradicating and preventing H. pylori.

• Journal of Life Science
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• v.33 no.4
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• pp.334-342
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• 2023

Forty species of lactic acid bacteria isolated from gajami sikhae were identified as Lactobacillus plantarum, Leuconostoc mesenteroides, Lactobacillus brevis, and Weissella paramesenteroides. 10 of the 40 strains were selected and used for the test. In this study, experiments such as those using acid and artificial gastric juice resistance, bile acid resistance, autoaggregation, coaggregation, and cell surface hydrophobicity were conducted to utilize lactic acid bacteria separated from gajami sikhae as probiotics. The separated lactic acid strains showed high survival rates through displaying resistance to acidic and artificial gastric juices; L. plantarum GS11 showed the best resistance. Also, as a result of a measurement of bile acid resistance, all lactic acid bacteria stocks showed survival of more than 100% with a probiotic number of 10⁸ to 10⁹ log CFU/ml. After evaluating cohesion to indirectly measure cell surface adhesion, autoaggregation ability was shown to be more than 46%. Measurement of xylene adhesion for cell surface hydrophobicity evaluation revealed better cell adhesion than B. subtilis, which has 32.2% hydrophobicity in isolated lactic acid strains. Antibacterial force measurement found antibacterial activity in lactic acid bacteria, excluding L. plantarum GS12 and L. plantarum GS13. Therefore, it was judged that lactic acid bacteria separated from gajami sikhae could be used as probiotics with various probiotic properties.

• Journal of Life Science
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• v.30 no.6
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• pp.491-500
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• 2020

Lactic acid bacteria are widely known to prevent and treat intestinal health conditions, heart disease, depression, and obesity. In Korea, such bacteria are commonly consumed through various fermented foods, although most are isolated from kimchi, and research on the lactic acid bacteria in fermented seafood is insufficient. This study was therefore conducted to observe changes in bacterial flora according to the culture date of lactic acid bacteria in the fermentation of traditional Korean Gajami Sikhae produced in Pohang and to isolate the bacteria of probiotic value. The bacteria were periodically isolated and identified from date of preparation to 50 days after preparation to investigate which Lactobacillus are involved in Gajami Sikhae. As fermentation progressed, it was confirmed that Pediococcus sp. and Lactobacillus sp. participate predominantly in the early and later periods of fermentation, respectively. During the entire fermentation period, 170 isolates were screened, and the following five species were found to be involved: Pediococcus pentosaceus, Pediococcus inopinatus, Leuconostoc mesenteroides, Lactobacillus brevis, and Lactobacillus plantarum. Five strains of these species were selected through acid and bile tolerance tests, and their coaggregation, autoaggregation, hydrophobicity, antibacterial, and antioxidant activities were then evaluated. As a result, it is thought that L. brevis GS1022, which has excellent digestive fluid resistance, and P. inopinatus GS316, which has excellent cohesiveness, may be useful as probiotic strains.

• Food Science of Animal Resources
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• v.31 no.2
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• pp.176-182
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• 2011

The bacteriocin-producing lactic acid bacteria Enterococcus faecium DB1 was isolated from Korean traditional gajami sikhae. Culture conditions were optimized by response surface methodology (RSM) to maximize bacteriocin DB1 production. E. faecium DB1 displayed the highest bacteriocin activity when grown in modified MRS medium containing sucrose, rather than glucose, as a carbon source. The effects of temperature, initial pH, and sucrose concentration were tested to determine the optimum conditions for maximum bacteriocin production by E. faecium DB1. A central composite design was used to control the three variables in the experiment. RSM revealed that the optimum values for bacteriocin production were 27.66 g/L sucrose, temperature of $34.37^{\circ}C$, and an initial pH of 6.54. A 2.08-fold increase in bacteriocin production was obtained with sucrose-containing MRS medium compared to production in standard MRS medium.

• KSBB Journal
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• v.13 no.4
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• pp.343-351
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• 1998

About 75 strains which utilize cholesterol as sole carbon and energy source were isolated from 10 samples of Kimchi and 18 samples of fermented fish food (2 Ojingo-jeots, salt-fermented squid ; 5 Changran-jeots, salt-fermented pollack tripe ; 5 Myungran-jeots, salt-fermented Alaska pollack roe ; 3 Gajami-sikhae-jeots, fermented flat fish ; 2 Gul-jeots, salt-fermented oyster ; a Juneo-jeots, salt-fermented shad). Among them tested, the 3T6-5Mj strain isolated from Changran-jeot showed the highest activity on cholesterol degradation. The optimal composition of medium for the producing cholesterol degradation enzyme by 3T6-5Mj strain was 1.0 g/L NH4NO3, 1.0 g/L K2HPO4, 0.1 g/L MgSO4.7H2O, 1.0 g/L FeSO4.7H2O, 1 g/L NaCl, 5 g/L Trypton, 1 g/L Cholesterol, and 5 g/L Maltose at 30$^{\circ}C$, pH 7.5, and the enzyme production reached a maximum level at 140 hours of cultivation.

• Food Engineering Progress
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• v.21 no.1
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• pp.88-92
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• 2017

We attempted to investigate antibacterial and proteolytic activities of bacteria isolated from three ethnic fermented seafoods in the east coast of South Korea, gajami sikhae, squid jeotgal, and fermented jinuari (Grateloupia filicina). Bacillus cereus ATCC 14579, Listeria monocytogenes ATCC 15313, Staphylococcus aureus KCTC 1916, Escherichia coli O157:H7 ATCC 43895, and Salmonella enterica serovar Typhimurium ATCC 4931 were selected to determine the antibacterial activity of the bacterial isolates. Among 233 isolates from the three foods, 36 isolates (15.5%) showed antibacterial activity against B. cereus ATCC 14579, the highest incidence of inhibition, followed by S. aureus KCTC 1916 (7.7%) and L. monocytogenes ATCC 15313 (6.0%). However, only five and three strains among the isolates exhibited inhibitory activity against Gram-negative indicators, E. coli ATCC 43895 and Sal. enterica ATCC 4931, respectively. The proteolytic activity of the isolates was determined via hydrolysis of skim milk after 24, 48, and 72 h incubation. After 72 h incubation, 72 out of 233 isolates (30.9%) showed proteolytic activity, and the isolates of fermented jinuari exhibited the highest incidence of proteolytic activity (60%, 36 isolates). These results suggest that ethnic fermented seafoods in the east coast of South Korea might be a promising source of bacterial strains producing antibacterial and proteolytic compounds.