Screening and characterization of microorganisms with fibrinolytic activity from fermented foods

Fibrinolytic microorganisms were screened from 42 samples of Korean fermented food (7 kinds of Chungookjang, 14 kinds of commercial Doen-jang, 5 kinds of home-made Doen-jang, and 16 kinds of Jeot-gal), 15 samples of Japanese fermented food (5 kinds of home-made soybean paste, and 10 kinds of Natto), and 19 samples of Indonesian fermented food (Tempe) as well as starters of Meju (500 microflora from Korea, and 22 from China). Initially, 11 isolates with strong fibrinolytic activity were selected for further characterization. The fibrinolytic activity of the 11 isolates ranged from 89 to 199% of standard plasmin. Four strains, M51 from Korean fermented food (Meju), I 1-1, I 1-4, and I 5-1 from Indonesian fermented food (Tempe), were chosen based on the degree of activity and reproducibility, and identified as Staphylococcus sciuri, Citrobacter or Enterobacter, Enterococcus faecalis, and Bacillus subtilis, respectively. The first two isolates are pathogenic strains while the latter two are considered as GRAS (Generally Recognized As Safe). Fibrinolytic activity of E. faecalis, characterized and designated as BRCA-5, reached a maximum, when the producer was cultivated in M17 broth supplemented with 1.0% glucose for 5 h at 37°C with shaking at 180 rpm. Compared to commercial fibrinolytic enzymes, the cell-free culture supernatant of E. faecalis BRCA-5 showed stronger activity than plasmin and streptokinase, but similar degree of specific activity as nattokinase and urokinase, and it also demonstrated anticoagulant and antiplatelet activity ex vivo. These features of E. faecalis make it an attractive agent as a biomaterial for health-promoting foods.