Alginate sources

Table 1. M G ratios from various alginate sources (46,47). Alginate Source Laminaria hyperborea...

Commercial applications for polysaccharides include their use as food additives, medicines and industrial products. Although plant polysaccharides (such as starch, agar and alginate) have been exploited commercially for many years, microbial exopolysaccharides have only become widely used over the past few decades. The diversity of polysaccharide structure is far greater in micro-organisms compared to plants and around 20 microbial polysaccharides with market potential have been described. However, microorganisms are still considered to be a rich and as yet underexploited source of exopolysaccharides. 

Rapidase C-80 (Gist -brocades) was used as enzyme source. The fractionation procedure of the crude preparation included chromatography on Bio-Gel PIO (100-200 mesh), DEAE-Bio-Gel A, and Bio-Gel HTP (Bio-Rad, Richmond, CA, USA). Other column materials used were cross-linked alginate (degree of cross-linking 2.34, prepared in our laboratory). Phenyl Superose HR 5/5 and Mono Q HR 5/5 (Pharmacia Biotech, Uppsala, Sweden). 

One example for a chemically defended zooplankton species is the Antarctic pteropod Clione antarctica. This shell-less pelagic mollusk offers a potentially rich source of nutrients to planktivorous predators. Nonetheless fish do not prey on this organism, due to its efficient chemical defense. In a bioassay-guided structure elucidation, pteroenone 37 could be isolated and characterized as the main defensive principle of C. antarctica [82,83]. If embedded in alginate, this compound is a feeding-deterrent in nanomolar concentrations. This unusual metabolite is likely to be produced by C. antarctica itself and not accumulated from its food, since its major food sources did not contain any detectable quantities of 37. 

These materials are another polysaccharide. The name derives from its original source, brown algae. The current commercial sources are brown seaweeds such as Laminaria digitata, L. hyperborea, Ascophyllium nodosum and Fucus serratus. Different properties are obtained in alginates from different seaweeds. The sources are rocky coasts in the United States, the United Kingdom, France and Norway. 

Biotransformations of morphinan alkaloids have been reported for plant, fungal, and mammalian enzymatic systems with emphasis on rather specific reactions such as the reduction of ketones, N- and O-demethylation, and perox-idative transformations. Furuya et al. used immobilized tissue culture cells of Papaver somniferum to accomplish the selective reduction of codeinone (135) to codeine (136) (207) (Scheme 30). Suspension cultures of a well-established cell line of P. somniferum were grown for one week as a source of cell mass for immobilization in calcium alginate. The cells continued to live in the alginate matrix for 6 months maintaining their biological activity. The reduction of co-... 

Rao and Hall compared the activities of algae, cyanobacteria, and photosynthetic bacteria entrapped in an alginate gel and in a hydrophilic polyurethane. Their opinion was that such systems could maintain effectiveness for years using sunlight as an energy source. 

The ability of alginates to form edible gels by reaction with calcium salts is an important property. Calcium sources are usually calcium carbonate, sulfate, chloride, phosphate, or tartrate (20). The rate of gel formation as well as the quality and texture of the resultant gel can be controlled by the solubility and availability of the calcium source. 

Algin or Alginic Acid is a protein of marine algae and is found in many seaweeds. Its principal source of prepn is as a by-product of the extraction of iodine from kelp, principally from Laminaria digitata. It has been used mainly in Japan, for the prepn of films, fabric dressing, and for thickening jellies. Its soln in Na carbonate can be used as a... 

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