α-Amylase 및 protease 활성을 동시에 가지는 1-B-12 균주를 된장으로부터 분리하였다. 16S rRNA 유전자 염기서열 분석결과, Bacillus licheniformis로 동정되어 B. licheniformis 1-B-12 균주로 명명하였다. 효소활성 측면에서 현미(50%), 미강(30%) 및 대두(20%)의 조합이 최적의 기질 조합 조건으로 확인되었다. 기능성이 부가된 효소식품을 제조하기 위하여 Lactobacillus casei GW140 균주를 도입하였는데, B. licheniformis 1-B-12 균주와의 혼합배양 조건은 2단발효(B. licheniformis 1-B-12 접종 > 24 h 발효 > L. casei GW140 접종 > 12 h 추가 발효)가 적합한 것으로 나타났다. 이러한 최적 조건으로 생산된 효소식품을 동결건조하여 25℃에서 보관하였을 때 시험 마지막 날인 45일까지 효소의 활성이 유지되었다.

1-B-12 strain presenting α-amylase and protease activity was isolated from a local Doenjang product. The strain was identified as Bacillus licheniformis by 16S rRNA gene sequencing and named B. licheniformis 1-B-12. A combination of raw materials with unpolished rice (50%), rice bran (30%), and soybean (20%) was best for the enzyme activities. A lactic acid bacterium Lactobacillus casei GW140 was applied for co-culture with B. licheniformis 1-B-12 aiming at the production of a function-added enzyme food. Two-step fermentation, where 24 h fermentation with B. licheniformis 1-B-12 and additional 12 h fermentation with L. casei GW140 were performed, resulted in maintenance of both of the enzyme activities and high level of lactic acid bacteria cell count. Furthermore the freeze-dried enzyme food sample was stable at 25℃ for 45 d which was the last day we tested.

• 강조은(한국교통대학교 생명공학과, Dept. of Biotechnology, Korea National University of Transportation) | Jo-Eun Kang
• 문기성(한국교통대학교 생명공학과, Dept. of Biotechnology, Korea National University of Transportation) | Gi-Seong Moon Corresponding author