Hydrolysis of carbohydrates in marine Tetraselmis sp by acid and enzymatic pre-treatments to obtain substrate for ethanol production

Hydrolysis of carbohydrates in marine Tetraselmis sp by acid and enzymatic pre-treatments to obtain substrate for ethanol production Eko Agus Suyono1,2 and Eva Albers1 suyono@chalmers.se 1Department of Chemical & Biological Engineering-Industrial Biotechnology Chalmers University of Technology Göteborg, Sweden 2Faculty of Biology Gadjah Mada Unversity Yogyakarta, Indonesia The current exploitation of renewable natural resources for large-scale biofuel production is neither sustainable in an environmental, nor economical or social perspective. To produce sustainable raw materials, it is necessary to find an efficient way of using photosynthetic organisms to obtain a carbon neutral production of biomass to be used in the biofuel production. A highly appealing solution is the culturing of microalgae for such production. In fact, microalgae has been said to have a realistic potential as biomass source for a sustainable large-scale production of fuel bioethanol. Using marine algae, which are able to grow in sea water, will be highly advantageous because globally the freshwater supply is limited. Since the highly complex carbohydrates are entrapped in the microalgal cell wall, it is essential to perform pre-treatment and hydrolysis steps to release these carbohydrates from the biomass and convert them into monosaccharides prior to the fermentation process. Hence, in this research we will study different methods for pre-treatment to open up the cells and a following enzymatic hydrolysis for Tetraselmis sp. The species used in this work was isolated from West Coast of Java Island in Indonesia and dilute acid exposure was used as the pre-treatment method and followed by enzymatic hydrolysis using cellulase and β-glucosidase to release fermentable sugars. The results showed that the highest glucose level of 0.02 g/l was obtained using 3% sulfuric acid (v/v) incubated at 100°C for 60 minutes. After treatment with 10 µl of Celluclast and 10 µl of Novozyme 188 (both Novozymes A/S) for 3 days, the amount of glucose released was increased to 0.16 g/l (0.06 g glucose/ g biomass) which account for 53% of its total carbohydrate content. However, further studies are needed to be done to find the best combination of sulfuric acid and enzymatic treatments in order to get optimum glucose release from the biomass of the microalgal strain