Table 2.

Some roles of microbial exopolymeric material (EPSs) in the marine environment. Adapted from [151].

Role of Exopolymer	Example
Assists in attachment to surfaces	Exopolymers of marine Vibrio MH3 were involved in reversible attachment. Cross-linking of adjacent polysaccharide chains aided in permanent adhesion.
Facilitates biochemical interactions between cells	Exopolymer mediated bacterial attachment to the polar end of blue-green N2-fixing alga. EPS aided attachment to symbiotic host such as vent tube worm to absorb metals and detoxify microenvironment. Exopolymer buffered against sudden osmotic changes.
Provides protective barrier around the cell	Bacteria in aggregates were less preferred by grazers than freely suspended bacteria. EPS-producing deep-sea hydrothermal vent bacteria showed resistance to heavy metals. Metal binding involves cell wall components as well as polysaccharides. Exopolymer in sea-ice brine channels provided cryoprotection by interacting with water at low temperature to depress freezing point. Nutrient uptake by bacteria in aggregates was higher than for free-living cells in low nutrient systems.
Absorbs dissolved organic material	Porous and hydrated matrix acts like a sponge and sequesters and concentrates dissolved organics.