Types of seaweed

Alginic types of seaweed, also called algin, is a naturally occurring, edible polysaccharide found in brown algae. It is hydrophilic and forms a viscous gum when hydrated. With metals such as sodium and calcium, its salts are known as alginates.

It is a significant component of the biofilms produced by the bacterium Pseudomonas aeruginosa, a major pathogen found in the lungs of some people who have cystic fibrosis. Alginates are refined from brown seaweeds. Throughout the world, many of the Phaeophyceae class brown seaweeds are harvested to be processed and converted into sodium alginate. Sodium alginate is used in many industries including food, animal food, fertilisers, textile printing, and pharmaceuticals. Alginates from different species of brown seaweed vary in their chemical structure resulting in different physical properties of alginates. Some species yield an alginate that gives a strong gel, another a weaker gel, some may produce a cream or white alginate, while others are difficult to gel and are best used for technical applications where color does not matter. Commercial grade alginate are extracted from giant kelp Macrocystis pyrifera, Ascophyllum nodosum, and types of Laminaria.

Chemically the process is simple, but difficulties arise from the physical separations required between the slimy residues from viscous solutions and the separation of gelatinous precipitates that hold large amounts of liquid within their structure, so they resist filtration and centrifugation. Alginate absorbs water quickly, which makes it useful as an additive in dehydrated products such as slimming aids, and in the manufacture of paper and textiles. Alginate is used as an ingredient in various pharmaceutical preparations, such as Gaviscon, in which it combines with bicarbonate to inhibit gastroesophageal reflux. Sodium alginate is used in reactive dye printing and as a thickener for reactive dyes in textile screen-printing. Calcium alginate is used in different types of medical products, including skin wound dressings to promote healing, and may be removed with less pain than conventional dressings.

Alginate hydrogel is a common biomaterial for bio-fabrication of scaffolds and tissue regeneration. Hyaluronic acid: a polysaccharide in animals. Pseudomonas aeruginosa in cystic fibrosis: pathogenesis and persistence”. Pseudomonas aeruginosa biofilms: role of the alginate exopolysaccharide”.