High temperature and low acid pretreatment and agarase treatment of agarose for the production of sugar and ethanol from red seaweed biomass

• DOI: 10.1016/j.biortech.2013.03.038
• Publication Date: 2013-03-16T04:36:02Z
• Authors: Hee Taek Kim; Eun Ju Yun; Damao Wang; Jae Hyuk Chung; In-Geol Choi; Kyoung Heon Kim
• Keywords: 0301 basic medicine; Hot Temperature; Ethanol; Glycoside Hydrolases; Hydrolysis; Sepharose; Carbohydrates; Seaweed; 6. Clean water; 03 medical and health sciences; Fermentation; Carbohydrate Metabolism; Furaldehyde; Biomass; Chromatography, Thin Layer; Acetic Acid; Vibrio

To obtain fermentable sugar from agarose, pretreatment of agarose by using acetic acid was conducted for short durations (10-30 min) at low acid concentrations (1-5% (w/v)) and high temperatures (110-130 °C). On testing the pretreated agarose by using an endo-β-agarase I (DagA), an exo-β-agarase II (Aga50D), and neoagarobiose hydrolase (NABH), we observed that the addition of the endo-type agarase did not increase the sugar yield. Use of the crude enzyme of Vibrio sp. EJY3 in combination with Aga50D and NABH including acetic acid pretreatment resulted in a 1.3-fold increase in the final reducing sugar yield (62.8% of theoretical maximum based on galactose and 3,6-anhydrogalactose in the initial agarose), compared to those obtained using Aga50D and NABH only after acetic acid pretreatment. The simultaneous saccharification and fermentation of pretreated agarose yielded ethanol of 37.1% theoretical maximum yield from galactose contained in the pretreated agarose.