본 연구에서는 청국장 및 볏짚에서 분리한 미생물중 decarboxylase 배지에서 탈탄산효소 활성이 낮은 균주로 B. subtilis HH12, B. subtilis HR254, P. barcinonensis KR97을 선발하였다. 이들 선발 미생물들의 histidine decarboxylase(hdc) gene 과 tyrosine decarboxylase(tdc) gene을 조사한 결과, hdc gene은 HH12, HR254, KR97 균주에서는 검출되지 않았으나, tdc gene은 HH12, HR254, KR110 균주에서 검출되었다. 또한 HPLC를 통해 선발 균주들의 배양상등액 중 amines 생성량을 분석한 결과, HH12, HR254, KR110 균주는 histamine이 검출되지 않았고 tyramine은 HH12, HR254, KR110 균주는 각각 6.09, 3.68, 6.30 mg/L로 검출 되었다. 선발한 biogenic amines 저감화 균주들의 BAs 생성량을 decarboxylase 고생산 미생물로 사료되는 B. subtilis MC138 균주와 비교해보면 현저히 낮은 수준으로 나타났다.
Microorganisms, having the lower decarboxylase activity, among the isolated strains from cheonggukjang and rice-straw in this study were selected by using biogenic amine (BA) media. The selected strains were identified as Bacillus subtilis HH12, B. subtilis HR254, and Paenibacillus barcinonensis KR97, by using 16S rRNA analysis. PCR analysis showed that the histidine decarboxylase (hdc) gene was absent in the HH12, HR254, and KR97 strains. However, PCR analysis showed that the tyrosine decarboxylase (tdc) gene was present in the HH12, HR254, and KR97 strains. Quantitative analysis of the selected strains by using high-performance liquid chromatography showed that histamine was absent in the HH12, HR254, and KR97 strains. However, these 3 strains showed tyramine concentrations of 6.09, 3.68, and 6.30 mg/L, respectively. These strains produced lower concentrations of amines (approximately 7.9, 0, and 9.3% amines in the HH12, HR254, and KR97 strains, respectively) than the B. subtilis MC138 strain, which showed the higher protease activity.