Recently, petroleum-alternative energy is being issued in the world to meet increasing global energy usage and rapid climate change by greenhouse gases. The ‘bioenergy’ is one of the alternative and renewable energy using biomass as the energy source. The bioenergy is more valuable than other renewable energy, because of its availability to be used as a fuel for transportation or industries. Lignocellulosic biomass is a good energy source for generating biofuels: bioethanol, biodiesel, and biogas. It’s not only a non-food resource but also an abundant source in Korea with forest space for 64% of the nation’t total land area. However, it’s hard for enzymes to hydrolyze the lignocellulosic biomass because of their strict structures formed with main components consisted of cellulose, hemicellulose, and lignin. Plus, the crystalline parts in cellulose also resist to the enzymatic hydrolysis for saccharification of lignocellulose. For this reason, the pretreatment process to remove lignin and break the hydrogen bonds should be treated. After the fibers in lignocellulosic biomass became ready to be reacted as substrate of enzymes, the best conditions of enzymatic hydrolysis should be investigated and developed, depending on the chemical and structural characteristics of the biomass.
In this study, ‘Quercus mongolica’ and ‘Larix kaempferi’, which are well known species as the unused small-diameter logs in Korea, were used as the lignocellulosic biomass. The pretreatment of the biomass was treated with peracetic acid, which was formed during the chemical reaction between acetic acid and 30% hydrogen peroxide solution(CH3COOH:H2O2 = 3:7, v/v). The high oxidative pretreatment with reaction was held during 6 hours in 70℃ and 120 rpm shaking condition. After the delignification was almost over, the pretreated biomass was on saccharification by Novozymesⓡ Cellic CTec2 and HTec2.
At first, CTec2 and HTec2 were loaded independently to grasp each enzymes’ characteristics in hydrolysis reaction. Secondly, several main enzyme(CTec2) dosages were tested to find the most appropriate enzyme dosage for each species. Lastly, various enzyme ratios (CTec2:HTec2 = 1:9, 3:7, 5:5, 7:3, 9:1) were loaded to investigate the synergic effects between two enzymes, and surmise the main reasons that affect to the hydrolysis of mixed enzymes.