• Microbiology and Biotechnology Letters
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• v.39 no.3
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• pp.294-300
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• 2011

Proteolytic bacteria were isolated from Myeolchi-jeotgal and Saeu-jeotgal using high-salt-content media and their growths in the media containing 25% NaCl were monitored to draw the role of bacteria in the ripening of jeotgal. The most populous genus in Myeolchi-jeotgal detected on agar media with 15% NaCl was Bacillus and its relatives, while the most populous in Saeu-jeotgal was Staphylococcus. Among the isolates, Virgibacillus halodenitrificans from Myeolchi-jeotgal and Halobacillus trueperi from Saeu-jeotgal showed proteinase activities. The species from Myeolchi-jeotgal showed proteinase activity on the agar media with 8% NaCl were similar to those isolated from the media with 15% NaCl. The dominant of Myeolchi-jeotgal isolated at the 15% NaCl concentration may be involved in the proteolysis. The proteolytic species from Saeu-jeotgal on the agar media with 8% NaCl were the genera Bacillus, Salinicoccus, and Salimicrobium those were not the dominants at 15% NaCl condition. The dominant isolates from Saeu-jeotgal on agar media with 15% NaCl may not be involved in the proteolysis of Saeu-jeotgal. Vb. halodenitrificans and Staphylococcus equorum, the dominant species from Myeolchi-jeotgal and Saeu-jeotgal, showed growths at the nutrient broth containing 25% NaCl. They may play a significant role in the ripening of jeotgal and have a high possibility to be used as the starter.

• 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.

• Microbiology and Biotechnology Letters
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• v.44 no.3
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• pp.293-302
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• 2016

To determine the dominant bacterial species during the Saeu-jeotgal ripening process, the cultivable bacterial population was examined over a 135-day period using six different growth media. The greatest numbers of bacteria were identified when marine agar was used for culture, with maximum cell density identified at day 65 (2.51 × 10⁷ colony forming units/g). Over the course of 135 days, the bacterial diversity was analyzed eight times. A total of 467 isolates, comprising 87 species from 42 genera, as well as 16 isolates belonging to previously unknown species, were identified. The number of species detected decreased from 39 at day 1 to 13 at day 135. The order of dominance at the genus level was as follows: Staphylococcus, Salimicrobium, Kocuria, and Psychrobacter. Staphylococcus and Salimicrobium accounted for 2% of the diversity at day 1, and then increased to 39% and 36%, respectively, at day 135. The dominant species Staphylococcus equorum, Salimicrobium salexigens, and Kocuria palustris accounted for 23.6%, 16.1%, and 10.9% of all isolates, respectively. Importantly, both St. equorum and Sm. salexigens remained viable at a NaCl concentration of 21% (w/v), which indicates their strong involvement in the ripening of Saeu-jeotgal.

• Microbiology and Biotechnology Letters
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• v.45 no.3
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• pp.218-225
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• 2017

Saeu (shrimp) jeotgal (SJ) was prepared by mixing with 25% salt with different types: purified salt (PS), solar salt aged for 1 year (SS), and bamboo salt. SJ was fermented for 22 weeks at $15^{\circ}C$. Bacilli and marine bacteria were detected throughout the entire fermentation period, and marine bacteria were present in the largest numbers. Lactic acid bacteria (LAB) were detected only during the first 8-10 weeks, but yeasts appeared at the sixth week and later. Archaea were detected in low numbers only from SS-SJ during the first 8 weeks. BS- SJ showed higher pH and lower titratable acidity (TA) values than other SJs because of strong alkalinity of bamboo salt. Amino-type nitrogen (ANN) contents of SJs increased during fermentation, especially, after 2 and 6 weeks. SS-SJ showed the highest ANN content from the beginning to the end of fermentation. Ammonia-type nitrogen (AMN) contents also increased like the amino-type nitrogen during fermentation. The highest volatile basic nitrogen (VBN) was also observed in SS-SJ. Salinity was kept constant after 4 weeks. SS was better than other salts for SJ fermentation in terms of protein hydrolysis.