Bacterial surface active polymers

The biosynthesis of most crystalline polymers is not well understood. The mechanism by which structural and insoluble proteins are assembled from monomers into structures such as cell membranes is almost completely unknown (33). A notable exception is the biosynthesis of polysaccharides which is believed to take place by phosphate displacement reactions of an activated subunit with the help of an enzyme system (33). The polymerization of bacterial cellulose is perhaps studied in most detail. Here the research has been helped because the reaction of monomer to crystalline polymer occurs extracellularly, remote from the bacterial surface (34). 

Antifouling activity is one of the most important properties that catheters should ideally exhibit in order to prevent catheter-associated infections. To quantitatively investigate bacterial fouling on polymer-coated silicone rubber surfaces, the number of viable bacterial cells on the surfaces was measured [102]. After 1 day of incubation, there was a high number of viable Staphylococcus aureus and Escherichia coli cells on both pristine and thiol-functionalised surfaces (Staphylococcus aureus 8.8 and 8.6 log colony forming units (CFU), respectively Escherichia coli 8.5 and 8.2 log CFU, respectively) (Figure 6.1). 

Figure 34.2 Cell-surface interactions. The total energy of interaction (I) of a negatively charged bacterial cell with a negatively charged pellicle-covered enamel surface is shown as a function of separation distance in an aqueous solvent of moderate ionic strength. The cell is temporarily held in an energy minimum about 10 nm from the surface and is subsequently stabilized in this position by polymers which specifically interact with each surface. The polymers could be an integral component of the cell structure or be produced by bacterial metabolic activity or be a salivary component. They could also promote bacterial cell-cell interactions in the same manner. Key -( -[ specific recognition sites ...

The process of biochemical purification of industrial waste waters consists of biochemical destruction of organic impurities under the influence of biocenosis, the complex of all microorganisms in waste disposal works. The major part is played by bacteria which are capable of accumulating into zoogleas, i.e. active silt in the form of dark brown flakes. These flakelike aggregates form mostly by the interaction of fibrillar polymers produced and adsorbed by bacterial cells. The mobility of the flakes is connected with the metabolic processes in the cells, which change the surface of the flakes. 

Layer-silicates Recent studies have also demonstrated the potential microbial influence on clay mineral (layer silicates) formation at hydrothermal vents. Bacterial cells covered (or completely replaced) with a Fe-rich silicate mineral (putative nontronite), in some cases oriented in extracellular polymers (as revealed by TEM analysis), were found in deep-sea sediments of Iheya Basin, Okinawa Trough (Ueshima Tazaki, 2001), and in soft sediments, and on mineral surfaces in low-temperature (2-50°C) waters near vents at Southern Explorer Ridge in the northeast Pacific (Fortin etal., 1998 Fig. 8.6). The Fe-silicate is believed to form as a result of the binding and concentration of soluble Si and Fe species to reactive sites (e.g. carboxyl, phosphoryl) on EPS (Ueshima Tazaki, 2001). Formation of Fe-silicate may also involve complex binding mechanisms, whereas metal ions such as Fe possibly bridge reactive sites within cell walls to silicate anions to initiate silicate nucleation (Fortin etal., 1998). Alt (1988) also reported the presence of nontronite associated with Mn- and Fe-oxide-rich deposits from seamounts on the EPR. The presence of bacteria-like filaments within one nontronite sample was taken to indicate that bacterial activity may have been associated with nontronite formation. Although the formation of clay minerals at deep-sea hydrothermal vents has not received much attention, it seems probable that based on these studies, biomineralisation of clay minerals is ubiquitous in these environments. 

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