2. The viewpoint of metabolic network There is neither absolute starting point nor ultimate terminal point in meta bolic network, which consists of biochemical reaction networks and trans-membrane steps. Any intermediate meta bolite in meta bolic network or possibly the compound to be connected to metabolic network by means of biology or chemistry, would be developed into a target product or a starting material for industrial fermentation2. The viewpoint of metabolic network There is neither absolute starting point nor ultimate terminal point in metabolic network, which consists of biochemical reaction networks and trans-membrane steps. Any intermediate metabolite in metabolic network, or possibly the compound to be connected to metabolic network by means of biology or chemistry, would be developed into a target￾product or a starting material for industrial fermentation