Formation of Trehalose from Maltooligosaccharides by a Novel Enzymatic System

A trehalose-producing bacterium, Arthrobacter sp. strain Q36, was isolated from soil. From a supernatant of the culture broth, two novel enzymes related to trehalose synthesis were partially purified by Sepabeads FP-DA column chromatography. One enzyme catalyzed the conversion of maltopentaose into maltotriosyl trehalose by intramolecular transglycosylation, showing it to be maltooligosyl trehalose synthase. The other hydrolyzed the product transferred by the former into maltotriose and trehalose specifically, showing it to be maltooligosyl trehalose trehalohydrolase. In addition to the bacterial strain isolated, several bacteria kept in our laboratory were found to produce these enzymes. The enzymatic system was proposed to be a novel biosynthesis of trehalose in bacteria involving the following reactions: maltodextrin→maltooligosyl trehalose, maltooligosyl trehalose→maltodextrin + trehalose. When these enzymes acted on amylose simultaneously, the trehalose in the reaction mixture reached more than 80% in content.