structure of eps share a lot of similarities with bacterial ones. the formation of biofilm starts with reversible absorption of floating cells to the surface. followed by production of eps, the adsorption will get irreversible. eps will colonize the cells at the surface with hydrogen bonding. replication of early colonizers will be facilitated by the presence of organic molecules in the matrix which will provide nutrients to the algal cells . as the colonizers are reproducing, the biofilm grows and becomes a 3-dimensional structure. microalgal biofilms consist of 90% eps and 10% algal cells. algal eps has similar components to the bacterial one; it is made up of proteins, phospholipids, polysaccharides, nucleic acids, humic substances, uronic acids and some functional groups, such as phosphoric, carboxylic, hydroxyl and amino groups. algal cells consume eps as their source of energy and carbon. furthermore, eps protects them from dehydration and reinforces the adhesion of the cells to the surface. in algal biofilms, eps has two sub-categories; soluble eps (seps) and the bounded eps (beps) with former being distributed in the medium and the latter being attached to the algal cells. bounded eps can be further subdivided to tightly bounded eps (tb-eps) and loosely bounded eps (lb-eps). several factors contribute to the composition of eps including species, substrate type, nutrient availability, temperature, ph and light intensity.