Phosphorylated bacterial cellulose

Bacterial cellulose (BC)/HAp nanocomposites were examined by Wan et al. [279]. The most striking features of BC are its high mechanical sdength and modulus, as well as its biodegradability. Compared with other natural biodegradable polymers, BC presents much better mechanical properties, which are required in most cases when used as scaffold in tissue engineering. Compared with animal-derived polymers, BC is free of any occurrence of cross-infection that can be associated with collagen [276]. The authors found that there are different interactions between unphosphorylated and phosphorylated BC fibres and HAp, as shown schematically in Fig. 26. 

The biosynthetic pathway that produces bacterial cellulose from glucose and fructose is shown in Fig. 14.2. Glucose is phosphorylated by glucose hexokinase and not by the phosphoenolpyruvate (PEP)-dependent phosphotransferase system (PTS). The resulting glucose-6-phosphate (G6P) is metabolized through the pentose pathway, because the activity of fructose-6-phosphate (F6P) kinase, which phos-phorylates F6P to fructose-1,6-diphosphate (FDP), is absent in acetic acid bacteria. 

In order to utilize essential metallic ions as nutrients for growth, microorganisms must have the ability to adsorb and concentrate metal cations fi om solution. In many microorganisms, this may be accomplished, in part, through electrostatic interactions with reactive acidic groups (carboxyl and phosphoryl) contained within the constituent polymers of microbial cell walls (36,37), A number of experimental studies have clearly demonstrated that substantial quantities of various metals can be bound and accumulated by a variety of bacterial cells (38-40), whereas Kuyucak and Volesky (41) have shown that the cellulosic materials in filamentous algae played an important role in the biosorption of gold. 

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