Bacterial Alginate

Alginate is a linear polymer composed of mannuronic acid and glucuronic acid (both of them being uronic acids) in a proportion ranging from 4 1 to 20 1. Some of the mannuronic acid residues are acetylated (Fig. 2.7). 

Alginate Gold nanoparticle To encourage cellular interactions [26] 

Alginate Silk sericin loaded nanoparticles To promote antiinflammatory efficacy [27] 

Polyvinyl alcohol/sodium alginate Nanoparticles Antibacterial activity [28] 

Chitosan/alginate pH-sensitive core-shell nanoparticles For efficient and safe oral insulin delivery [30] 

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Other examples of exocellular homopolysaccharides whose biosynthetic process has been investigated include D-mannuronan,204,205 an intermediate in the biosynthesis of bacterial alginic acid (mentioned in Section III,l,c), and bacterial cellulose. 

With xanthan gum, continuous fermentation243-245 resulted in lower estimates of cost for its production. Also, with the production of bacterial alginate by Azotobacter vinelandii, serious loss of substrate by respiration could be minimized by proper selection of the conditions in the continuous fermentor.62 With some micro-organisms, the desired metabolites are not produced, owing to selection of less-productive strains. Apparently, this selection occurred with Xanthomonas campestris246 when Rogovin and coworkers243-245 found that production of xanthan decreased after —8-10 fermentor turnovers. 

The kind of polysaccharides that are isolated from different bacteria are as follows Alginate, a linear copolymer with (l-4)-linked p-D-mannuronate and its a-L-guluronate residues that is produced by two bacterial genera Pseudomonas species and Azotobacter vinelandii [4]. Bacterial alginates are useful for the production of micro- or nanostructures suitable for medical applications. Cellulose, a p (1—>4) linked D-glucose unit obtained from Acetobacter xylinum. Cellulose of plant origin is usually impure as it contains... 

The continuous production of bacterial alginate from A. vinelandii coupled to membrane-based extraction appears to be possible but more detailed investigation must still being performed in order to optimize the process. However, it should be remarked the possibility of controlling the stmcture of resultant alginates obtained by using genetically modified bacteria. 

SabraW, Zeng A-P, DeckwerW-D. Bacterial alginate physiology, product quality and process aspects. 

Day, D.F. and R.D. Ashby, Bacterial alginates — a potentially useful class of biopolymers. Proceeding of ACS... 

Other water-soluble microbial polysaccharides include the anionic polysaccharides gellan from Pseudomonas elodea and bacterial alginate from Pseudomonas aeruginosa, and the neutral polysaccharides scleroglucan, curdlan, and pullulan (72,75,76,83). 

Studies with alginate lyases have revealed the presence of 0-acetyl groups in bacterial alginates. The 0-acetyl groups may ensure that some of the D-mannopyranosyluronic acid residues do not epimerize during the biosynthesis of alginates. 

Table 2.5 Drug delivery applications of bacterial alginate...

The production of commercial alginates is around 50,000 ton per year worldwide mainly extracted from algal sources, but recently some bacterial alginates are also produced extra-cellularly by Pseudomonas aeruginosa and Azotobacter vinelandii. 

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