Biosynthesis of Cellulose by Acetobacter Xylinum. II. Morphological Observations on the Formation of Cellulose Microfibrils by Acetobacter Xylinum

Abstract

Electron-microscopic observations of an early stage of a logarithmic phase of bacterial cellulose formation show ill-defined and branched fibrillar elements extending from an amorphous substance of cell envelope. This may be interpreted as the initial crystallization of a cellulosic high polymer. In the photographs of cell cross sections, it has been observed that rather slightly staining rod-like materials about 30-40A in breadth and ca. 1000A in length are in the cytoplasm of some cells. Composite fibrils become predominant at a middle stage of a logarithmic growth phase. They were in the form of threads having a constant breadth of ca. 500A with sharply defined boundaries, and consisting of a few microfibrils. The separate fibrils have intertwined to form tangled masses, and built tough membranes which could not be torn easily. Lysozyme treatment of the microfibril has demonstrated that the shape is a fiat ribbon with a constant breadth and a thickness of ca. 50-100A. This treatment has the effect of hydrolytic degradation across the axial direction of the microfibril. In addition, a pronounced swelling of the microfibril occurs anisotropically perpendicular to the axis of the microfibril. A bacterial cellulose membrane negatively stained with sodium phosphotungstate, showed a longitudinal periodicity with a ca. 200A interval. KEY WORDS Incubation I Bacterial Cellulose 1 Fibrillar Element I Cell Envelope I Cross Section I Rod-like Material I Composite Fibril 1 Microfibril I Tangled Mass I Membrane I Lysozyme Treatment 1 Negative Staining Periodicity 1

Investigation of the micro- and nano-scale architecture of cellulose hydrogels with plant cell wall polysaccharides: A combined USANS/SANS study

“…At the next structural level, bacterial cellulose ribbons have been reported to be periodically twisted along their longitudinal axis [55,56,[62][63][64]. The mechanism leading to the development of twists has not yet been established.…”

“…Based upon TEM images, the ribbon twisting periodicity has been estimated as ca. 1 µm [64,67]. Moreover, 73.50 (6) Parameters displayed with (*) were fixed during the fitting process.…”