A unique biochemical reaction pathway towards trehalulose synthesis by an amylosucrase isolated from Deinococcus deserti

The aim of this study was to establish an efficient bioprocess for the synthesis of trehalulose as a novel sweetener. This disaccharide has 70% of the sweetness of sucrose and bioactive properties such as anti-cariogenicity and anti-oxidizing activity. In this study, amylosucrase from the Deinococcus deserti (DdAS) gene was expressed and purified. When DdAS was reacted with 2 M sucrose at 35 degrees C for 120 h, the yield ratio of trehalulose to turanose was approximately 2:1. The trehalulose yield increased when extrinsic fructose was added. Under optimum conditions for trehalulose synthesis, the yield reached 36% (246 g/L, sucrose basis) starting with 2 M sucrose + 0.75 M fructose and showed the highest trehalulose productivity (1.94 g/L/h). As a result, a novel amylosucrase that synthesized trehalulose as the major product was developed, in contrast to other studied amylosucrase-type enzymes. DdAS could be utilized industrially in a bioprocess for producing trehalulose as a functional sucrose alternative.