The Fibrilzation of Cellulose Gel Biosynthesized by Acetobacter xylinumt

Abstract

The fibrilzation of cellulose gel biosynthesized by Acetobacter xylinum was studied by means of electron microscopy. Acetobacter xylinum was incubated in O.0 2 wt% glucose solution (pH 6.8 ) with and without added 0.2 w t% sodium tungstophosphate on the sheet mesh cove red collodion membrane for a given time at 28.0°C. The fibril obtained from the latter culture medium was stained with 0.2 wt% sodium tungstophosphate solution before drying. The cellulose fibril after the biosynthesis was homogeneous and amorphous. The amorphous state of the fibril was kept for about 30 min. In course of time, the inhomogeneous distribution of cellulose took place perpendicular to the long axis of the amorphous fibril. Finally many microscpic fibrils with the width of about 40-50Å appeared simultaneously in the amorphous fibril in about 5 h after biosynthesis. The bacterial cellulose microfibril was found to be composed of these microscopic fibrils. The negative staining-stuff contained in the culture medium scarcely influenced the fibrilzation of cellulose gels. It is not clear whether the appearance of the microscopic fibril found in this study is due to the crystallization or the biosynthesis of the amorphous fibril. The fact that the microscopic fibril always appears in all amorphous fibrils seems to indicate that there are cellulose chains not randomly but regularly oriented in the amorphous fibril.