Extracellular polymeric material

A majority of these microorganisms can form extracellular polymeric materials known as polymer or slime. The slime helps glue the organisms to the surface, trap, concentrate nutrients as food for microbes and shields the organisms from biocides. 

The sequence of events involved in the initial fouling process has been investigated (8), and a two-phase attachment process with a reversible and irreversible attachment phase was described. During the initial reversible phase, bacteria are held to the surface by weak attractions. Firmer binding occurs when physical and chemical forces combine to hold the bacterial cells irreversibly to the surface (e.g. via extracellular polymeric material). The initial fouling process is probably preceded by adsorption of dissolved organic... 

Werner, C., Pompe, T. and Salchert, K. Modulating Extracellular Matrix at Interfaces of Polymeric Materials. Vol. 203, pp. 63-94. 

The ability of the stone-colonizing microflora to cover and even penetrate material surface layers by the excretion of organic extracellular polymeric substances (EPS) leads to the formation of complex slimes, or biofilms, in which the microbial cells are embedded. Phototrophic organisms usually initiate colonisation by establishing a visible, nutrient-rich biofilm on new stone from which they can penetrate the material below to seek protection from high light intensities or desiccation. Stone EPS trap aerosols, dust and nutrients, minerals,... 

Natural organic matter from biosynthesis and biodegradation is ubiquitous in natural aqueous environments. Common examples of natural organic materials are extracellular polymeric matrices (biofilms) generated by bacteria, hydrocarbons from industrial effluents and fossil fuel products, and numerous humic substances. Because of their hydrophobicity, natural organic materials have low solubility in water and tend to accumulate at solid surfaces. As a result, in groundwater and soils, mineral surfaces are commonly coated with organic films. 

Analysis of the Pb EXAFS data from the Fe-plaque revealed a Pb-0 interatomic distance of 2.4 A, which is inconsistent with published data for Pb sorbed to Fe-oxides (-2.27 A). Furthermore, optimized fitting of the second shell EXAFS function was obtained for C or N at a distance of 3.4 A, which is longer than previous reports for Pb bound humic material (Hansel et al. 2001). Based on fits that included a sample where Pb was bound to microbial biofilm it was concluded that the Pb was bound to a microbial biofilm-like material apparently intimately associated with the Fe-plaque. This finding demonstrates the important role of microorganisms in rhizosphere processes and the preferential binding of Pb to extracellular polymeric substances even in the presence of a highly reactive high surface area Fe-oxide phase. 

While the binding of fibronectin appears to be a critical feature in the response of cells to many man-made materials, recent studies have shown that treatment of surfaces with other extracellular matrix components, such as laminin and type IV collagen (60), can greatly alter the biological properties of plastics. Treatment of plastic with a biomatrix derived from a basement membrane tumor can alter the morphology and differentiated state of several cell types (60). Hence, the biological properties of polymeric materials are dependent on the type of extracellular atrix molecule absorbed more than the chemical nature of the polymer itself. 

The environmental interactions of CdSe QDs in abiotic environments are expected to be enhanced in biological environments due to the presence of biofilms (89). Biofilms are bacterial cells attached to surfaces where the cells multiply and produce extracellular polymeric substances (EPS) (90). Thus, a biofilm is a combination of cells, polysaccharides, nucleic acids, proteins, and inorganic material that may form structured channels (91, 92). The biophysiochemical interactions between biofilms and CdSe QDs can include binding and uptake, decomposition, and expulsion. These processes may have toxic repercussions for biological organisms. 

Biodegradation normally refers to an attack by microorganisms on water insoluble polymers. This implies that the biodegradation of plastics is usually a heterogeneous process. Due to the lack of water solubility and the size of the polymer molecules, miaoorganisms are unable to transport the polymeric material directly into the cells where most bioehemical processes take place rather, they must first excrete extracellular enzymes, which de-polymerize the polymers outside the cells. As a consequence, if the molar mass of the polymers can be sufficiently reduced to generate water-soluble intermediates, they can be transported into the miaoorganisms and fed into the... 

Also, not all of the biofilm is biological material Biofilms are believed to typically contain about 95% water. In fact, the breakdown of a biofilm mass has been reported as being predominantly water (85%-95% wet weight), bacteria (109-1011 cells/mL), and extracellular polymeric substance (EPS) (l%-2% wet weight). ... 

Sadr, N., Pippenger, B.E., Scherberich, A., Wendt, D., Mantero, S., Martin, 1., Papadimitropoulos, A., 2012. Enhancing the biological performance of synthetic polymeric materials by decoration with engineered, decellulaiized extracellular matrix. Biomaterials 33, 5085-5093. 

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