Screening of lovastatin-producing strains by PCR using lovastatin biosynthesis genes

Lovastatin 생합성 유전자를 이용한 lovastatin 생산균주의 탐색

  • Ko, Hee-Sun (National Institute of Agricultural Science and Technology, RDA) ;
  • Kim, Hyun-Soo (Department of Microbiology, College of Natural Science, Keimyung University)
  • 고희선 (농촌진흥청 국립농업과학원 농업미생물과) ;
  • 김현수 (계명대학교 자연과학대학 미생물학과)
  • Published : 2009.04.29

Abstract

Lovastatin (also known as Mevinolin, Mevacor, and Monacolin K), an inhibitor of the HMG-CoA reductase produced by Aspergillus terreus and other fungi, is used to reduce serum cholesterol levels in human beings. It is derived biosynthetically from two polyketides. One of these is a nonaketide that undergoes cyclization at a hexahydronaphthalene ring system, and the other is a simple diketide, 2-methylbutyrate. Two primer pairs were designed based on the amino acid sequences of lovastatin polyketide synthase and lovastatin diketide synthase for the PCR screening of lovastatin-producing strains. Among the seven selected strains, SJ-2 evidenced the highest level of lovastatin production in both liquid and solid cultures. Soybeans with SJ-2 were treated via 1 hour of heat shock at $30^{\circ}C$ for the mass production of lovastatin. The heat-treated soybeans were inoculated on rice bran and the koji extract was obtained after 15 days of incubation. It yielded the highest level of lovastatin production among the strains, and also evidenced 75% inhibition activity against HMG-CoA reductase. We developed an efficient PCR screening method for lovastatin-producing strains, using lovastatin biosynthesis genes.

본 연구는 Asp. terreus ATCC 20542 변이주로부터 lovastatin 생합성 유전자 중 polyketide 생합성 유전자 등을 이용한 PCR법으로 Aspergillus sp. 이외의 statin계열 물질 생산균주의 탐색법 구축 및 lovastatin 대량생산을 하고자 하였다. Lovastatin 생합성 유전자 중 가장 중요한 유전자인 polyketide synthase gene와 diketide synthase gene로부터 각각의 primer를 제작하여 PCR을 이용한 lovastatin 생산 균주를 탐색하였다. 선발된 7개의 균주의 형태학상의 특성 및 lovastatin 생산성을 검토한 결과 Aspergillus sp. 이외의 Penicillium sp.으로 추정되는 균주를 재선발하여 SJ-2로 명명하였다. 선발된 SJ-2는 액체배양 및 고체배양을 한 후 추출하여 TLC와 HPLC를 통하여 각각의 lovastatin 생산량을 비교, 검토하였다. 또한, SJ-2에 대두를 이용하여 lovastatin 고생산성을 확인한 결과, 대두-전배양체를 $30^{\circ}C$, 1시간동안 열처리하여 접종하여 본배양 15일째에 가장 높은 lovastatin을 생산할 수 있었다. In vitro assay 결과에서는 HMG-CoA reductase에 대한 저해활성도가 75%로 나타났다. 본 연구는 기존의 lovastatin 탐색법으로 널리 알려져 있는 bioassay법이 아닌 lovastatin 생합성 유전자를 이용하여 PCR을 통한 lovastatin 생산균주의 탐색이 신속하고 효과적인 방법으로 사료되었다.

Keywords

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