Acetobacter xylinum

Wahrend Citronellal bereits 1915 mit Hefe zu Citronellol1 (59% d. Th.) reduziert wurde und aus einem d,/-Gemisch mit Candida reukaufii nur die die /-Form reduziert wird5, un-terliegt Citronellal mit Acetobacter xylinum oder Acetobacter ascendens der Cannizzaro-Disproportionierung6. 

In 1886, Brown11 discovered an organism which formed extremely tough membranes when cultivated m suitable nutrient solutions containing carbohydrates such as D-fructose, D-mannitol or D-glucose ethanol, sucrose or starch did not support membrane formation by this organism which Brown called Bacterium xylinum ) (Acetobacter xylinum). The membranes were readily soluble in cuprammonium hydroxide solution and yielded a dextrorotatory sugar upon acid hydrolysis. These properties and the results of combustion analysis led him to believe that the membrane was cellulose. 

The identification of terminal complexes in the Gram-negative bacterium Acetobacter xylinum now appears to be in doubt. Previously, a single linear row of particles observed on the outer lipopolysaccharide membrane... 

Isolation and sequencing of the cellulose synthase gene(s) has not been accomplished yet however, DNA from Acetobacter xylinum containing this gene(s) was cloned into broad host-range plasmid vectors (82). These vectors were mobilized into Pel- mutants to test for complementation. To date, this approach has not produced a pellicle-forming transconjugant from a Pel- mutant of Acetobacter (82). The direct correlation between cellulose production and presence of plasmid DNA in Acetobacter has been reported... 

Triple-Stranded Left-Hand Helical Cellulose Microfibril in Acetobacter xylinum and in Tobacco Primary Cell Wall... 

Tobacco primary cell wall and normal bacterial Acetobacter xylinum cellulose formation produced a 36.8 3A triple-stranded left-hand helical microfibril in freeze-dried Pt-C replicas and in negatively stained preparations for transmission electron microscopy (TEM). A. xylinum growth in the presence of 0.25 mM Tinopal disrupted cellulose microfibril formation and produced a... 

The gram negative bacterium Acetobacter xylinum produces a ribbon of crystalline cellulose I whose neutral sugar content is 96.8% glucose and 3.2% xylose (1). Growth of A. xylinum in a medium containing... 

L-Iditol (sorbi6rite), the last of the four naturally occurring hexitols, occurs in service berries along with sorbitol. After removing sorbitol from the juice by fermentation to L-sorbose with the sorbose bacterium, Acetobacter xylinum, the n-iditol is crystallized as a benzylidene derivative. It has been prepared by the action of sodium amalgam on... 

Acetan of Acetobacter xylinum has pentasaccharide side chains that contain L-rhamnose.122 A helical structure for the strands has been observed by atomic force microscopy. 

The bacterial cellulose synthase from Acetobacter xylinum can be solubilized with detergents, and the resulting enzyme generates characteristic 1.7 ran cellulose fibrils (Fig. 20-4) from UDP-glucose.125/127-129 These are similar, but not identical, to the fibrils of cellulose I produced by intact bacteria.125 130 Each native fibril appears as a left-handed helix which may contain about nine parallel chains in a crystalline array. Three of these helices appear to coil together (Fig. 20-4) to form a larger 3.7-nm left-handed helical fibril. Similar fibrils are formed by plants. In both... 

A series of poly prenyl diphosphates was formed when EDTA-treated cells of Acetobacter xylinum were incubated with glycosyl nucleotides. The most complicated of them is the heptasaccharide derivative344 (32), which is considered to be an intermediate in the biosynthesis of the exocellular... 

The reducing end groups in cellulose are the only naturally occurring carbonyl functionalities in this material. Cellulose from Acetobacter xylinum [43] contains an amount of carbonyl groups which corresponds approximately to the number of reducing end groups, and can be considered as rather genuine material. 

Methyl-L-sorbose (LXXI)150 was prepared from the corresponding 4-methyl-L-gulitol (3-methyl-D-glucitol) (LXX) by oxidative fermentation with Acetobacter xylinum. The starting material was obtained by hydrogenation of 3-methyl-D-glucose (LXIX). 

Fig. I.—Proposed Model of Cellulose Assembly in Acetobacter xylinum. [d-GIu-can chain aggregates from organized, multiple-enzyme complexes, and extrusion pores crystallize into microfibrils, which then assemble into bundles and the normal ribbon at the cell surface.]...

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