The Korean Journal of Mycology (한국균학회지)

The Korean Society of Mycology (한국균학회)
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Identification and Characterization of Aspergillus oryzae Isolated from Soybean Products in Sunchang County

순창군 장류로부터 분리된 황국균의 동정 및 특성

  • Lim, Eunmi (Institute of Sunchang Fermented Soybean Products) ;
  • Lee, Ji Young (Institute of Sunchang Fermented Soybean Products) ;
  • Elgabbar, Mohammed A. Abdo (Department of Pharmaceutical Engineering, Woosuk University) ;
  • Han, Kap-Hoon (Department of Pharmaceutical Engineering, Woosuk University) ;
  • Lee, Bo-Soon (Department of Catering and Culinary Service, Woosuk University) ;
  • Cho, Yong Sik (Fermented Food Science Division, National Academy of Agricultural Science, RDA) ;
  • Kim, Hyoun-Young (Institute of Sunchang Fermented Soybean Products)
  • Received : 2014.11.03
  • Accepted : 2014.12.18
  • Published : 2014.12.30
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Abstract

In this study, we attempted to isolate fungi from soybean fermented foods produced in Sunchang County and to identify Aspergillus oryzae from fungal isolates. Ten fungal isolates were identified with ${\beta}$-tubulin gene. According to the sequences of ${\beta}$-tubulin gene, ten fungal isolates were identified as A. oryzae/flavus complex. For further identification of the ten of fungal isolates, omtA gene, one gene of the aflatoxin biosynthesis gene cluster, was sequenced and the sequences were compared with those of A. oryzae and A. flavus strains from the GenBank database. In addition, identification of the ten fungal isolates was further confirmed using the PCR amplicon of norB and cypA intergenic region, in which a deletion was recognized relative to A. flavus and A. parasiticus. The amplicon size of the ten fungal isolate strains was smaller than those of A. flavus and A. parasiticus, but the same as that of the reference A. oryzae strain. These results indicated that the ten isolates should be identified as A. oryzae. The protease activity in rice koji made with 6, 13, 17, 27, 37 and 38 of strain, respectively was twice higher than that in control. The kojis made with nine of the A. oryzae isolates, respectively, did not produce aflatoxin, suggesting that the strains could possibly be used as starters for soybean products.

본 연구에서는 순창지역에서 만들어지는 장류에서 곰팡이를 분리하고 동정하여 보다 안전하고 기능성이 높은 발효제품을 위한 균주를 확보하고자 하였다. 순창지역에서 생산되는 장류 제품으로부터 곰팡이를 분리하여 ${\beta}$-tubulin 유전자 분석 통해 10개의 균주가 Aspergillus oryzae/flavus complex임을 알 수 있었다. 보다 정확한 동정을 위하여 아플라톡신 클러스터 유전자 중에 하나인 omtA의 염기서열을 증폭하여 A. oryzae와 A. flavus 표준 균주의 omtA 서열과 함께 계통 분류한 결과, A. oryzae의 표준 균주와의 유연관계가 높음을 알 수 있었다. 또한 norB-cypA 사이의 염기서열을 증폭한 결과 500 bp이 증폭 산물이 확인되었는데 이는 표준 균주인 A. oryzae의 norB-cypA 사이의 염기서열 증폭 산물과 동일한 크기임을 확인할 수 있었다. A. oryzae로 확인된 10균주를 활용하여 코지를 제조하고 ${\alpha}$-amylase 활성과 protease 활성을 측정하였다. Protease 활성은 6, 13, 17, 27, 37, 그리고 38 균주로 제조된 코지는 대조구(시판되고 있는 종균으로 제작한 코지)보다 2배 정도 높은 protease 활성을 보였으며, ${\alpha}$-amylase 활성은 257~320 U/mL로 측정되었다. 식품안전성을 위한 아플라톡신 분비 확인 결과, 63번 균주로 제조된 코지를 제외한 모든 코지에서 아플라톡신을 만들지 않는 것으로 확인되어, 순창에서 분리된 A. oryzae는 추후 메주 접종균으로 개발할 수 있음을 보여주었다.

Keywords

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