Surface bacterial biofilms

Microorganisms vary tremendously in their susceptibility to chemical disinfectants. Prions, bacterial endospores and mycobacteria possess the most innate resistance, while many vegetative bacteria and some viruses appear highly susceptible (see Chapter 17). In addition, microorganisms adhering to surfaces as biofilms or present within other cells (e.g. legionellae within amoebae), may reveal a marked... 

Stafslien, S. J. Bahr, J. A. Feser, J. M. Weisz, J. C. Chisholm, B. J. Ready, T. E. Boudjouk, R, Combinatorial materials research applied to the development of new surface coatings I A multiwell plate screening method for the high-throughput assessment of bacterial biofilm retention on surfaces, J. Comb. Chem. 2006, 8, 156-162... 

Biofilms consist of surface-associated colonies of bacteria and are a major concern for implanted medical devices and in many diseases [120-122], Bacterial biofilms are highly organized communities embedded in an exopolysaccharide matrix, and contain several layers of bacteria with distinct functions. Biofilms grow slowly but efficiently to coat abiotic surfaces, and can eventually almost completely fill up narrow tubing. Because of the entrenched structure of biofilms, an antibiotic cannot penetrate deeply enough into the distant parts of the biofilm to kill all bacteria. Therefore, biofilms are difficult to remove mechanically or by means of antibiotics or disinfectants. 

The extent to which the factors that are important for biofilm formation on abiotic surfaces are also important for biofilm formation on biotic surfaces (e.g. in uroepithe-lial IBCs) is not known, and needs to be studied further. The observation of bacterial biofilm formation on abiotic surfaces mediated by (glyco)proteins [123] is highly... 

No commercial substrate is completely resistant to surface bacterial growth and biofilm formation. In a study at the University of Minnesota, PFA with a smooth surface was found to be least hospitable to bacterial growth. Biofilm removal from PFA was eas-... 

As shown in Figure 9, Fe and Pb are closely associated in a rind on the root surface which consists of 63% ferrihydrite, 32% goethite, and 5% siderite, as determined by later XAFS analysis. More detailed XAFS analysis of these samples carried out at SSRL showed that Pb is complexed with organic functional groups, most likely those of bacterial biofilms. Arsenic, which also appears to be associated in part with iron, is present as a combination of two sorbed As species ( 82% As(V) and 18% As(III)). Mn and Zn occur as isolated nodules of mixed-metal carbonate (rhodochrosite/hydrozincite) on the root surface. 

In this chapter we also address the core-sheU structure of metal fluorides for the case of FeF2, where the FeF2 is the core and carbon is the shell. According to Fedorov et al. (10), water will react very slowly with fluorides, yielding HF. The carbon shell is important because it will prevent this dissolution. Finally the use of metal fluorides to produce sterile abiotic surfaces and block bacterial biofilm formation is discussed. 

Figure 4.1 Presentation of bacterial biofilm development on abiotic surfaces, (a) Adhesion initially involves reversible association with the surface. As this proceeds bacteria undergo irreversible attachment with the substrate through cell surface adhesions. In later stages bacteria will start secreting a protective extracellular matrix and form microcolonies that develop into mature biofilms. These structures protect the bacteria firam host defenses and systemically administered antibiotics, (b) An electron micrograph of a biofilm-infected catheter.

A unique type of corrosion referred to as copper by-product release, cuprosolvency, or blue water occurs in potable water systems constructed of copper tubing, and has been reported worldwide [92-95]. The problem is most often attributed to EPS induced metal concentration cells. The condition is characterized by the release of copper as fine particles in plumbing systems distributing soft water in the neutral or neutral-alkaline pH range. Water may contain between 5 to 300 ppm copper (as Cu +) as finely suspended precipitates. A bacterial biofilm and associated acidic EPS bind copper ions at the metal surface and alter the porosity of the oxide film [96]. Geesey and coworkers [97] characterized binding of an acidic polysaccharide to thin copper films and su ested a cupric ion interaction with carboxyl groups on EPS. These interactions promoted ionization of metallic... 

Figure 23.2.6. GCW process diagram. Effective hydrocarbon stripping in the water column is observed in these systems using a vacuum extraction. A circulation cell is created by directional flow of water in the vertical direction creating a capture zone extending several meters from the well. In addition a bioreactor (high surface area bacterial biofilm) can be used in the system to degrade low volatile contaminants [Adapted from Bemhartt et al., U.S. Patent 5,910,245, 1999]...

Epstein AK, Hochbaum Al, Kim P, Aizenberg J. Control of bacterial biofilm growth on surfaces by nanostructural mechanics and geometry. Nanotechnology 2011 22 494007. 

Francolini I, Norris P, Piozzi A, et al. Usnic acid, a natural antimicrobial agent able to inhibit bacterial biofilm formation on polymer surfaces. Antimicrob Agents Chemother November 2004 48(11) 4360-5. 

Bacterial biofilms are able to protect materials by inducing changes in the chemical composition of the steel surfaces by excreting so-called... 

Scanning eiectron micrographs showing (a) bacterial biofilm developed on the surface of a protective coating bar = 5 ftm] and (b) biofilm on the same coating, containing a biocide, but with the bacteria killed bar = 5 pm]... 

Boyd A, Chakrabarty AM (1994) Role of alginate Ipse in cell detachment of Pseudomonas aeruginosa. Appl Environ Microbiol 60 2355-2359 Boyer MB, Hsu JT (1992) Experimental studies of restricted protein diffusion in an agarose matrix. Am Inst Chem Eng J 38 259-272 Bremer P J, Geesey GG, Drake B (1992) Atomic force microscopy examination of the topography of a hydrated bacterial biofilm on a copper surface. Curr Microbiol 24 223-230... 

No commercial substrate is completely resistant to surface bacterial growth and biofilm formation. In a study at the University of Minnesota, PFA with a smooth surface was found to be least hospitable to bacterial growth. Biofilm removal was easily and completely accomplished from PFA (Table 13.49). PFA was cleaned more completely than glass, stainless steel, and PVDF. Figure 13.112 shows the results of bacterial count in a dynamic ultrapure water system in which fouling of the surfaces of stainless steel, PVDF, and ECTFE were studied. ECTFE and PVDF were orders of magnitude less susceptible to biofouling than stainless steel. 

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