The major carbohydrate in red macroalgae is agarose, which is composed of d-galactose and 3,6-anhydro-l-galactose (AHG). So far, agarose saccharification was most efficiently achieved by prehydrolysis using a weak acid and subsequent enzymatic hydrolysis into monomeric sugars. However, this process requires rigorous neutralization after acid prehydrolysis, resulting in the formation of salts. Moreover, residual agarotriose is not further hydrolyzed by currently available β-agarases. In this study, we aimed at eliminating or minimizing the neutralization step by using a low-concentration acid-base buffer such as 20 mM (0.3%, w/v) Tris-HCl for hydrothermal pretreatment of agar at 170 °C for 10 min. In order to hydrolyze agarotriose, an agarolytic β-galactosidase acting on odd-numbered agarooligosaccharides, was introduced into the enzymatic saccharification. Using these chemical and enzymatic processes, the monomeric sugar yields of 44.9% for galactose and 44.8% for AHG on the basis of their theoretical maximum amounts from the initial agar were obtained.
Bibliographical noteFunding Information:
This research was supported by grants of the Fishery Commercialization Technology Development Program of the Ministry of Oceans and Fisheries ( 2012100788 ) and the Advanced Biomass R&D Center of Korea ( 2011-0031353 ) funded through the Korean Government (MSIP). Experiments were performed at the Korea University Food Safety Hall for the Institute of Biomedical Science and Food Safety.
© 2015 Elsevier Ltd.
- Agarolytic β-galactosidase
- Hydrothermal pretreatment
- Red macroalgae
ASJC Scopus subject areas
- Applied Microbiology and Biotechnology