Analysis of the cultivable bacterial community in jeotgal, a Korean salted and fermented seafood, and identification of its dominant bacteria

Jeotgal or jeot, a traditional Korean salted and fermented food, is made by adding 20-30% (w/w) salt to various types of seafood. To develop a more complete overview of the bacterial community present in jeotgal, 610 pure colonies were isolated from Myeolchi-jeot and Saeu-jeot, the most commonly consumed varieties of jeotgal, which are made with anchovy (Engraulis japonicas) and tiny shrimp (Acetes japonicas), respectively. The bacterial isolates were identified by 16S rDNA sequence analysis. A total of 104 species comprising 47 genera and 31 previously unknown species were identified. Eleven genera were isolated from both jeotgal samples, including species in the genera Staphylococcus, Bacillus, Halomonas, and Kocuria, with Staphylococcus spp. constituting the highest number. The most populous genus detected in Myeolchi-jeot was Bacillus and its relatives, while the most populous in Saeu-jeot was Staphylococcus. These were isolated from both jeotgal samples, but their proportion in the bacterial community may be influenced by matrix composition and fermentation parameters. Among the proteolytic isolates, although Virgibacillus halodenitrificans KM2100 and Staphylococcus spp. maintained their growth in 20% NaCl, protease activities were not detected in these conditions. This suggests that bacteria are not the major source of the proteolytic enzyme involved in protein hydrolysis in high-salt-containing jeotgal. However, the Staphylococcus spp. isolated from Saeu-jeot were too numerous for us to ignore their possible role in jeotgal fermentation. Staphylococcus spp. may not be hugely involved in proteolysis, but they may play a significant role in the ripening of jeotgal. Bacteria of the genus Bacillus and its relatives and of the genus Staphylococcus may be the major organisms involved in jeotgal fermentation. (C) 2010 Elsevier Ltd. All rights reserved.