Multiple starters consisting of two Bacillus amyloliquefaciens strains (MJ1-4 and EMD17), Pichiafarinosa SY80, and Rhizopus oryzae were used for Doenjang making. Bacillus strains were selected based on their abilities to inhibit toxinogenic fungi and Bacillus cereus, fibrinolytic activity, and their ability to confer good flavor to Cheonggukjang. P. farinosa SY80 and R. oryzae, previously isolated from soy sauce, were selected because they were not inhibited by two bacilli. Doenjang was prepared by inoculation of multiple starters (A1 Doenjang). Control Doenjang was prepared by inoculation of B. subtilis KACC 16750 (Natto strain) and Aspergillus oryzae KCCM 60166 (A2 Doenjang). Another control (A3 Doenjang) was prepared by inoculation of microorganisms present in rice straw. Doenjang samples were fermented for 70 days at 20℃. pH of 3 samples decreased from the initial value of 6.4 to 5.8~6.0 and titratable acidity (TA) increased from 0.6 to 1.1~1.3. The amount of amino-type nitrogen increased during fermentation. There were slight differences in moisture, crude-protein, and crude-fat contents after 70 days. Contamination of fungi was observed only in A3 Doenjang and B. cereus was not detected from all 3 samples. A1 Doenjang showed the highest fibrinolytic activity and A2 Doenjang the second. These results indicate that Doenjang made with carefully selected starters was functionally improved and microbially more safe.

본 연구는 전통대두발효식품에서 분리한 Bacillus amyloliquefaciens EMD17, HCD2, 그리고 MJ1-43 균주들과 B. subtilis W42 균주의 혈전용해능과 식염저항성을 조사함으로써 대두발효식품 제조에 종균으로 유용한 균주들을 확보하는 것이다. EMD17과 HCD2는 본 연구를 통해 B. amyloliquefaciens 균주들로 동정되었고 우수한 혈전용해능을 지님이 4 종류의 배지에서의 배양을 통해 확인되었다. B. amyloliquefaciens MJ1-4와 B. subtilis W42 균주들은 각각 항진균력과 항균력이 우수한 균주들로 보고된 바 있으나 혈전용해능은 알려지지 않았다. 본 연구를 통해 이들 2 균주도 혈전용해능을 지님이 확인되었다. 항균력과 혈전용해능이 우수한 바실러스 균주들을 종균으로 사용하는 것은 비단 식중독균 오염을 줄여줄 뿐 아니라 혈전용해능과 같은 기능성도 높여줌으로써 궁극적으로 고품질의 대두발효식품 제조에 기여할 것이다.