Table 1 A side of the roles accompanied to exopolysaccharides in the biofilms [105]

Adhesion

EPSs make provision for the initial steps in the colonization of surfaces by abiotic, biotic, and long-term attachment of the biofilms.

Bacterial cell aggregation

The bridging between cells is enabled by EPSs, leading to the subsequent development of high cell densities and cell-cell recognition.

Water retention

Hydrophilic EPSs have high water retention ability thus maintaining a hydrated microenvironment around the biofilm leading to the survival of desiccation in water-deficient environments.

Cohesion of biofilms

Neutral and charged EPSs form a hydrated polymer network, known as the biofilm matrix, mediating the mechanical stability of biofilms, determining the biofilm architecture, as well as allowing cell-cell communication.

Nutrient source

EPSs serve as source of carbon, nitrogen and phosphorus containing compounds for utilization by the biofilm community.

Protective barrier

EPSs confer resistance to non-specific and specific host defenses during infection. They confer tolerance to various anti-microbial agents and protect cyanobacterial nitrogenase from the harmful effects of oxygen and offers protection against some phagocytic protozoa.

Sorption of organic compounds and inorganic ions

Charged and hydrophobic EPSs mediate the accumulation of nutrients from the environment, sorption of xenobiotics and recalcitrant materials. They promote polysaccharide gel formation resulting in ion exchange, mineral formation and the accumulation of toxic metal ions, contributing collectively to environmental detoxification.

Sink for excess energy

EPSs stores excess carbon under unbalanced carbon to nitrogen ratios.

Biofouling formation

By accumulating the microorganisms that able to secret EPSs on wetted surfaces or vehicles, then followed by plants, algae, or animals.