Capsulan is the exopolysaccharide

Exopolysaccharide

Exopolysaccharides are high-molecular-weight polymers that are composed of sugar residues and are secreted by a microorganism into the surrounding environment. Microorganisms synthesize a wide spectrum of multifunctional polysaccharides including intracellular polysaccharides, structural...

 which makes up the thick capsule

Capsule

-Anatomy:* an eggshell* Articular capsules - every diarthrodial joint possesses a fibrous or ligamentous capsule, lined with synovial membrane, attached to the adjacent ends of the articulating bones* the sac that encloses the crystalline lens of the eye...

 surrounding the unicellular alga Prasinococcus capsulatus

Prasinococcus capsulatus

In taxonomy, Prasinococcus capulatus is a species of algae, specifically of the Prasinococcus. The name "'capulatus'" coming from the alga's large capsule which surrounds the cell. This unicellular algal species was discovered in 1990 in the West Pacific Ocean and has characteristic reproduction...

.

Extraction

Capsulan is extrated from cell cultures of P. capsulatus using the French Press

French press

A French press, also known as a press pot, coffee press, coffee plunger, cafetiere or сafetière à piston, is a simple coffee brewing device that was first patented by Italian designer Attilio Calimani in 1929....

 method to burst the cells. Alternatively the cells may be boiled.
Composition
Capsulan has been found to be mostly carbohydrate

Carbohydrate

A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...

 (70%) with some protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 and sulphur. The main sugars making up the carbohydrate are galactose

Galactose

Galactose , sometimes abbreviated Gal, is a type of sugar that is less sweet than glucose. It is a C-4 epimer of glucose....

 and glucose

Glucose

Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

 while other sugars such as xylose

Xylose

Xylose is a sugar first isolated from wood, and named for it. Xylose is classified as a monosaccharide of the aldopentose type, which means that it contains five carbon atoms and includes an aldehyde functional group. It is the precursor to hemicellulose, one of the main constituents of biomass...

, arabinose

Arabinose

Arabinose is an aldopentose – a monosaccharide containing five carbon atoms, and including an aldehyde functional group.For biosynthetic reasons, most saccharides are almost always more abundant in nature as the "D"-form, or structurally analogous to D-glyceraldehyde.For sugars, the D/L...

 and mannose

Mannose

Mannose is a sugar monomer of the aldohexose series of carbohydrates. Mannose is a C-2 epimer of glucose. It is not part of human metabolism, but is a component of microbial cell walls, and is therefore a target of the immune system and also of antibiotics....

 are also present in smaller quantities. Sugar acids

Sugar acids

Sugar acids are monosaccharides with a carboxyl group.Main classes of sugar acids include:* Aldonic acids, in which the aldehyde functional group of an aldose is oxidized...

are common in plant and algal polysacchride but there is disagreement in the literature concerning capsulan's sugar acid content. Kurano claims that capsulan contains none, while Myklestad maintains that both galacturonic and glucuronic acids are present.