Hydrolysis of Water-Soluble and Water-Insoluble Cellulosic Substrates by Endo-,B -1,4-Glucanase from Acetobacter xylinum

Morphology changes in bacterial cellulose produced by Acetobacter xylinum ATCC23769 were ob­ served in the presence of /3 -glucodisaccharides such as gentiobiose and cellobiose. Endo-/3 -1,4-glucanase ac­ tivity in culture broth was higher than that in the absence of those sugars. So we have investigated the prop­ erties of endo-/3 -1,4-glucanase (AEG) produced by this bacterium. This enzyme could hydrolyze water-soluble cellulose such as CMC, hydroxyethyl cellulose and cellodextrin, and decreased the viscosity of the substrate solution. On the other hand, AEG could not produce any soluble sugars from water-insoluble cellulose such as Avicel and bacterial cellulose. These properties were completely different from endo-glucanase from fungi. AEG hydrolyzed cellohexaose and produced cellobiose, cellotriose and cellotetraose, but in the presence of bacterial cellulose, the soluble sugars produced from cellohexaose disappeared in the reaction mixture. It is suggested that AEG might have transglycosyl activity, though it belongs to glycosidase family 8. It is proposed that this activity is closely related to cellulose synthesis.