Recombinant agarase increases the production of reducing sugars from HCl-treated Gracilaria verrucosa, a red algae

One of the most intensively studied species in red algae is Gracilaria spp., which is also a highly abundantly produced species annually in Asian countries including Korea and Japan. Much of the recent work on production of reducing sugars from Gracilaria spp. has concentrated on a combined process of physicochemical and biochemical treatments using acids and commercial enzymes. To the best of our knowledge, this study is first demonstration of combined acid and enzymatic hydrolysis using recombinant agarase to produce total reducing sugar (TRS) from Gracilaria verrucosa. By performing acid hydrolysis under the specified condition (2% biomass, 0.1 N HCl, 121 degrees C, 15 min), a 34.9% TRS yield was obtained. Subsequent enzymatic hydrolysis using two recombinant agarases (aga 50D 0.5 U/mg + NABH 0.5 U/mg), resulted in a 47.4% TRS yield was achieved. The TRS yield obtained from acid and enzymatic hydrolysates was 5% higher than that of previous study with commercial enzyme. These results served to demonstrate that feasibility of enzymatic hydrolysis using the recombinant agarases to produce TRS from G. verrucosa for bio-refinery applications. (c) 2017 Elsevier B.V. All rights reserved.