Edible microorganisms are attracting much attention as sustainable food resources to change existing food production system such as agriculture and livestock, which are causing environmental problems including climate change. Therefore, we aimed to establish edible microorganism-based food production system that can utilizes C1 compounds and produce beneficial nutrients including protein as a solution for problems above. Firstly, probiotic strain E. coli Nissle 1917, which has been consumed as a medicine for diarrhea treatment and considered as safe, was chosen as an edible biomass production platform for sustainable food application. In addition, among the C1 compounds, powerful greenhouse gas $CO_2$ and its reduced form formic acid (FA) were selected as alternative carbon sources. To convert the carbon metabolism of E. coli Nissle 1917 to assimilate C1 compounds, we applied systems metabolic engineering strategies. Here, we metabolically engineered E. coli Nissle 1917 strain to produce edible biomass carbon from $CO_2$ and formic acid by reconstruction of Calvin-Bassham-Benson cycle and by tetrahydrofolate cycle together with reverse glycine cleavage pathway. This is the first case of conversion of heterotrophic edible microorganism into synthetic carbon assimilating strain, which is widely applicable for establishment of sustainable edible microorganism production.
식용 미생물은 기후 변화 등 환경 문제를 일으키고 있는 농업, 축산 등의 기존 식량 생산 체계를 변화시킬 지속가능한 식량자원으로 주목받고 있다. 본 연구에서는 오랜 시간에 걸쳐 섭취되어온 안전하고 인체에 유용한 유산균인 E. coli Nissle 1917 균주를 식용 바이오 매스 생산 플랫폼으로 하였다. 대사공학 전략을 사용하여 E. coli Nissle 1917 내에 C1 가스를 동화하는 대사경로인 Calvin-Bassham-Benson 회로와 테트라하이드로엽산 및 역글리산 회로를 구축함으로써 E. coli Nissle 1917이 이산화탄소와 개미산으로부터 식용 바이오매스를 생산할 수 있도록 하였다. 본 연구는 종속영양 식용미생물을 대사공학으로 이산화탄소 및 개미산 고정 균주로 엔지니어링에 성공한 사례로 향후 다양한 식용 미생물의 C1 가스로부터의 생장 및 식품 생산에 기반을 마련하였다.
