Extracellular polymeric substances (EPS)

Definition

Extracellular polymeric substances (EPS) are a mixture of polysaccharides, proteins, lipids, and nucleic acids produced by microorganisms, playing a vital role in biofilm formation and environmental interactions. These substances enhance microbial adhesion to surfaces, protect cells from harsh conditions, and facilitate nutrient exchange, making them crucial in various geological and ecological processes.

5 Must Know Facts For Your Next Test

1. EPS contributes to the mechanical stability of biofilms, allowing them to withstand shear forces from water flow.
2. Microorganisms within biofilms produce EPS as a defense mechanism against antibiotics and other harmful agents.
3. EPS can influence the geochemical properties of the surrounding environment, affecting nutrient cycling and mineral dissolution.
4. The composition of EPS varies significantly among different microbial species and environmental conditions, leading to a wide range of functional properties.
5. In carbonate formation processes, EPS can mediate the precipitation of calcium carbonate by altering local pH and providing nucleation sites.

Review Questions

• How do extracellular polymeric substances contribute to the stability and resilience of biofilms in natural environments?
  • Extracellular polymeric substances provide structural integrity to biofilms by forming a protective matrix that shields the microbial community from environmental stresses like shear forces and antimicrobial agents. This matrix not only helps maintain the biofilm's structure but also enhances nutrient retention and exchange among microbial cells, promoting their survival and growth. Consequently, EPS play a key role in ensuring that biofilms remain stable and functional in diverse ecological settings.
• Discuss the role of EPS in microbial weathering processes and how this affects mineral dissolution.
  • Extracellular polymeric substances are crucial in microbial weathering as they can enhance the dissolution of minerals through their interaction with metal ions and modification of local pH levels. By producing organic acids and chelating agents within their EPS matrix, microorganisms can break down minerals more effectively. This process not only facilitates nutrient release for microbial uptake but also alters soil chemistry, impacting broader geological processes such as soil formation and nutrient cycling.
• Evaluate the implications of EPS production on carbonate formation processes in geochemical environments.
  • The production of extracellular polymeric substances significantly influences carbonate formation by providing nucleation sites for calcium carbonate precipitation. EPS can change local environmental conditions such as pH levels, promoting supersaturation with respect to carbonate minerals. This interaction results in enhanced mineralization rates that contribute to the development of carbonate rocks and sediments. Understanding these mechanisms is essential for assessing biogeochemical cycles and the role of microorganisms in shaping sedimentary geology.

Related terms

Biofilms: Structured communities of microorganisms that adhere to surfaces and are encased in a protective EPS matrix.

Mineralization: The process by which microorganisms facilitate the precipitation of minerals, often influenced by the presence of EPS.

Microbial Mats: Layered biofilms composed of diverse microbial communities, often found in extreme environments, that rely on EPS for structural integrity and stability.