• Journal of Microbiology and Biotechnology
• /
• v.28 no.7
• /
• pp.1112-1121
• /
• 2018

Jeotgal is a Korean traditional fermented seafood with a high concentration of salt. In this study, we isolated lactic acid bacteria (LAB) from galchi (Trichiurus lepturus, hairtail) and myeolchi (Engraulis japonicas, anchovy) jeotgal on MRS agar and MRS agar containing 5% NaCl (MRS agar+5% NaCl), and identified them by using 16S rRNA gene sequencing and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) as culture-dependent methods. We also performed polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) as a culture-independent method to identify bacterial communities. Five samples of galchi-jeotgal and seven samples of myeolchi-jeotgal were collected from different regions in Korea. A total of 327 and 395 colonies were isolated from the galchi- and myeolchi-jeotgal samples, respectively. 16S rRNA gene sequencing and MALDI-TOF MS revealed that the genus Pediococcus was predominant on MRS agar, and Tetragenococcus halophilus on MRS agar+5% NaCl. PCR-DGGE revealed that T. halophilus, Tetragenococcus muriaticus, and Lactobacillus sakei were predominant in both types of jeotgal. T. halophilus was detected in all samples. Even though the same species were identified by both culture-dependent and -independent methods, many species identified by the culture-dependent methods were not in the bacterial list identified by the culture-independent methods. The distribution of bacteria in galchi-jeotgal was more diverse than in myeolchi-jeotgal. The diverse LAB in galchi- and myeolchi-jeotgals can be further studied as candidates for starter cultures to produce fermented foods.

• Microbiology and Biotechnology Letters
• /
• v.49 no.1
• /
• pp.9-17
• /
• 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
• /
• v.54 no.6
• /
• pp.1045-1051
• /
• 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.