유해해양식물 Spartina sp.를 이용한 바이오연료 생산

Abstract

Growing public awareness of renewable energy, zero carbon and climate change is driving interest in the use of microbial fermentation technologies for biofuels and chemical production. This study was performed the production of ethanol and 2,3-butanediol from Spartina sp. as lignocellulosic waste. The invasive alien species Spartina sp. spread in Ganghwa-do, Han River estuary, Republic of Korea was used as a biomass resource. Waste Spartina sp. has high carbohydrate and fiber contents which can be obtained sugar. To obtain a high reducing sugar yield from Spartina sp.. The enzymatic saccharification and thermal acid pretreatment conditions was optimized. Experiments were carried out with various acid catalyst type, acid concentration, enzyme type, enzyme mixing ratio, reaction time and temperature. Finally, after adding 300 mM nitric acid (HNO3), 10% of biomass content heat treatment at 120°C for 60 minutes was selected as the optimal thermal acid hydrolysis condition. When enzymatic saccharification was conducted for 72 hours with Cellic CTec2 single enzyme after thermal acid hydrolysis, a maximum yield of 90.66% of enzymatic saccharification was obtained. Ethanol fermentation using Saccharomyces cerevisiae SR8, Candida tropicalis and Kluyveromyces marxianus was performed on the Spartina sp. hydrolysis. Among them, S. cerevisiae SR8 produced 16g/L ethanol with YEtOH=0.39 at 72 h. To increase the production of 2.3-butanediol (2,3-BDO), the ethanol production gene adh1 and the 2,3-butanediol production gene BDH1 involved in the 2,3-butanediol pathway of S. cerevisiae SR8 were engineered. Then, ethanol production and 2,3-BDO production were compared through fermentation in the Spartina sp. hydrolysis using the recombinant strain.