This study was performed to examine the microorganisms responsible for the high tyramine content of Cheonggukjang, a traditional Korean fermented soy food, and to establish a technology for controlling the growth of these microorganisms. The tyramine content in 13 collected Cheonggukjang samples averaged 604.9 mg/kg. Since the tyramine content measured from most samples was sufficient to cause harm to the human body, it is necessary to control its production in food. Enterococci were confirmed to be the bacterial species producing most of the tyramine through the microbial examination and were present in high numbers from not detected (<10(1)) to 7.0 × 10(10) colony-forming units (CFU)/g. To control the growth of enterococci, various plant extracts with antimicrobial activity, common salts, and variable temperature conditions were tested. It was found that 4 samples among the 159 plant extracts had a strong antimicrobial activity in Cheonggukjang, especially against Enterococcus faecium, showing viable cell counts of <10(1)-10(3) CFU/g after 24 h of ripening, which were significantly lower values compared to the control (10(9)-10(11) CFU/g). The Cheonggukjang with the addition of the four plant extracts showed ∼83%-95% lower concentrations of tyramine compared to the control. Cheonggukjang prepared with the Schizandra chinensis Baillon extract had the lowest tyramine content without sacrificing the sensory quality. Not only was the bacterial species of E. faecium reduced more remarkably, by up to 10(3) CFU/g compared to the 10(9)-10(11) CFU/g shown in the control, but it also decreased the tyramine content by up to 91%.

The purpose of this study was to isolate functional Bacillus strains from Korean fermented soybeans and to evaluate their potential as probiotics. The L-asparaginase activity of MKHJ 1-1 was the highest among 162 Bacillus strains. This strain showed nonhemolysis and did not produce β-glucuronidase. Among the nine target bacteria, MKHJ 1-1 inhibited the growth of Escherichia coli, Pseudomonas aeruginosa, Shigella sonnei, Shigella flexneri, Klebsiella pneumoniae, Staphylococcus aureus, and Bacillus cereus. 16S rRNA gene sequence analysis resulted in MKHJ 1-1 identified as Bacillus subtilis subsp. stercoris D7XPN1. As a result of measuring the survival rate in 0.1% pepsin solution (pH 2.5) and 0.3% bile salt solution for 3 h, MKHJ 1-1 exhibited high acid resistance and was able to grow in the presence of bile salt. MKHJ 1-1 showed outstanding autoaggregation ability after 24 h. In addition, its coaggregation with pathogens was strong. Therefore, MKHJ 1-1 is a potential probiotic with L-asparaginase activity and without L-glutaminase activity, suggesting that it could be a new resource for use in the food and pharmaceutical industry.

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A Gram-staining-positive, strictly aerobic, non-spore-forming, rod-shaped bacterial strain, CAU 9163 T , was isolated from marine sediment collected in the Republic of Korea and its taxonomic position was investigated using a polyphasic approach. The novel strain grew optimally at 30 6C and pH 8.0. In phylogenetic analysis based on 16S rRNA gene sequences, strain CAU 9163 T formed a hitherto unknown lineage within the order Bacillales, which contains the genera Planomicrobium, Planococcus, Sporosarcina, Rummeliibacillus, Viridibacillus, Lysinibacillus and Bacillus. The levels of 16S rRNA gene sequence similarity between the novel strain and any established bacterial species were all ,95.7 %. The major isoprenoid quinines of strain CAU 9163T were MK-8 (65.2 %) and MK-7 (22.8 %) and the predominant fatty acid was anteiso-C 15 : 0 . The peptidoglycan was of the A4a type and based on L-Lys-D-Asp. The major whole-cell sugars were ribose and glucose. The polar lipid profile mainly consisted of phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, an unidentified glycolipid and an unidentified polar lipid. The genomic DNA G+C content of the novel strain was 44.3 mol%. These data were sufficient to differentiate the novel strain from established genera in the phylum Firmicutes. Based on the phenotypic, chemotaxonomic and genotypic evidence, strain CAU 9163 T represents a novel species in a new genus for which the name Chungangia koreensis gen.nov., sp. nov. is proposed. The type strain of Chungangia koreensis is 9163 T (5KCTC 13729 T 5CCUG 59778 T ).

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