(587q) Enzyme Cocktail Design of ?-Agarase Enzymes for Complete Hydrolysis of Agarose in Ionic Liquid-Pretreated Gelidium amansii

Authors: 
Nisola, G. M., Myongji University
Weldemhret, T. G. K., Myongji University
Valdehuesa, K. N. G., Myongji University
Chung, W. J., Myongji University
Red macroalgae Gelidium amansii is a prospective renewable resource for producing D-galactose and 3,6-anhydro-L-galactose due to its ubiquity and high carbohydrate content. Its main component agarose, is a linear polysaccharide with alternate repeating units of D-galactose and 3,6-anhydro-L-galactose linked via β-1,4- and α-1,3-glycosidic bonds. Enzymatic saccharification using β-agarase enzyme system with subsequent acetic acid or thermal pre-hydrolysis is currently the most popular method to produce the monomeric sugars from agarose. However, accumulation of 5-hydroxymethylfurfural (HMF) as sugar dehydration product, and generation of agarotriose as a byproduct that is recalcitrant to complete enzymatic hydrolysis, have been typically encountered.

Ionic liquid (IL) pretreatment with subsequent enzyme cocktail hydrolysis using β-agarases is a facile strategy to effectively deconstruct and hydrolyze the agar into its monomeric sugars, and to eliminate the generation of unwanted products. Moreover, the use of an IL system as an effective and eco-friendly solvent could alleviate enzyme activity losses in unfamiliar solvent phases. Four ILs namely [EMIM]Cl, [BMIM]Cl, [EMIM]OAc and [BMIM]OAc were employed to dissolve G. amansii from which [BMIM]OAc was found most suitable. The enzyme cocktail of β-agarase I (endo-acting), β-agarase II (exo-acting), and neoagarobiose hydrolase (NABH) were subsequently used for D-galactose and 3,6-anhydro-L-galactose production from the IL-dissolved G. amansii. Performance optimization of IL-enzyme cocktail system is currently under investigation. This work was supported by the Korea Research Fellowship Program through the NRF funded by the Ministry of Science, ICT and Future Planning (2015H1D3A1062172 and 2016R1C1B1013252) and the Ministry of Education (2009-0093816).

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