An exopolymer is a

biopolymer Biopolymers are natural polymers produced by the cells of living organisms. Like other polymers, biopolymers consist of monomeric units that are covalently bonded in chains to form larger molecules. There are three main classes of biopolymers ...

that is secreted by an organism into the environment (i.e. external to the organism). These exopolymers include the

biofilm A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular ...

s produced by bacteria to anchor them and protect them from environmental conditions. One type of expolymer, Transparent Exopolymers (TEP), found in both marine and aquatic ecosystems, are planktonic acidic

polysaccharides Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with w ...

of a gel-like consistency, originally defined by their ability to be stained visible by acidic

Alcian Blue Alcian blue () is any member of a family of polyvalent basic dyes, of which the Alcian blue 8G (also called Ingrain blue 1, and C.I. 74240, formerly called Alcian blue 8GX from the name of a batch of an ICI product) has been historically the mo ...

. Their free-floating characteristic sets TEPs aside from other

extracellular polymeric substance Extracellular polymeric substances (EPSs) are natural polymers of high molecular weight secreted by microorganisms into their environment. EPSs establish the functional and structural integrity of biofilms, and are considered the fundamental comp ...

subgroups where exopolymers exists as cell coating, dissolved slime or as part of biofilm matrices. The formation of Transparent Exopolymer Particles(TEP) is mainly due to the abiotic coagulation of dissolved carbohydrates, which is secreted by the phytoplankton communities. Transparent Exopolymer Particles ((TEP) have the ability to form larger aggregates because of their strong surface active properties or “stickiness”. This particular property of TEP allows them to perform as a glue matrix for other solid particles including detritus. Transparent Exopolymer Particles (TEP) is also a carbon source for bacteria, which plays a significant role in affecting the food web structure and the

carbon cycle The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth. Carbon is the main component of biological compounds as well as a major componen ...

in the ocean. Additionally, the conversion of dissolved organic carbon (DOC) to particulate organic carbon (POC) is an aggregation process that is due to TEP formation.

References

Biomolecules Polymers {{Biochem-stub