Microbial attachment

Figure 15.2 Hyperbranched sialosides and related glycopolymers can inhibit microbial attachment to host tissues by blocking their receptor sites...

Hazardous substances may be protected from microbial attack by physical or chemical envelopes. These protective barriers must be destroyed mechanically or chemically to produce fine particles or waste suspensions to increase the surface area for microbial attachment and subsequent biodegradation. Another way to increase the bioavailability of hydrophobic substances is washing of waste or soil by water or a solution of surface-active substances (surfactants). The disadvantage of this technology is the production of secondary hazardous... 

Turner, J. T. (1979). Microbial attachment to copepod fecal pellets and its possible ecological significance. Trans. Am. Microsc. Soc. 98, 131—135. 

Biofilm development is affected by both physical and chemical factors. The abundance and condition of bacteria in the water column plays a major role in initial rate of settlement on a surface 181]. Surface factors such as wettability [82] and critical surface tension [83], surface hydrophobicity [84], fluid dynamic forces [85], shear stress [86], electrolyte concentration [87] and metabolic inhibitors [88] can all affect microbial attachment, adhesion or growth. The low surface energy of a gorgonian octocoral has been implicated as a passive fouling resistance mechanism used in conjunction with other antifouling defences [82]. 

Management approaches have therefore emphasized the need for prevention through the addition of good sterile technique at the time of insertion. Manufacturers have also responded by using materials and creating surface characteristics of implanted materials inclement to microbial attachment. Likewise the use of prophylactic antibiotics at the time of insertion of deep-seated devices such as joint and heart valve prostheses has further reduced the risk of infection. Once a medical device becomes infected, management is difficult. Treatment with agents such as flucloxacillin, vancomycin and most recently linezolid is often unsuccessful and the only course of action is to remove the device. 

The water in these systems is maintained at an elevated temperature and kept in continuous movement. Water velocity through pipes is sufficient to prevent microbial attachment. 

Microbial attachment to rocks and sand particles forms the basis for the largest and most extensive utilization of immobilized microbial cells in the world today trickling filters. 

E. Influence of Interfacial Films on Microbial Attachment. Air-water and solid-water interfaces accumulate surface-activeor hydrophobic organics present in the aqueous phase. Both the increased concentration of organic foodstuffs and the potentially increased adhesiveness of the interfacial film tend to increase the relative concentration of microbes at interfaces. In terms of cell immobilization, it may be possible to increase the strength of adhesion and the durability of the immobilized wholecell system by pre-coating the solid substrate with an appropriate interfacial film. 

To avoid this problem plastics are now used rather extensively as carriers for fixed-bed reactors (9,10,12), including denitrification (8). The shape and pore size of plastics can be controlled to give desirable flow characteristics, and the surface can be modified for better microbial attachment, e.g. by plasma treatment. In earlier applications no rigorous conditions or requirements existed for true immobilization of the microbes. Consequently, many cells were detached from the carrier to the effluent causing an increase in the BOD and COD of the effluent water (. ... 

The increased resistance of bacteria to antibiotic therapy is a growing concern for doctors and medical officials worldwide. In the last two decades bacteria have developed resistance to almost all the commercially available antibiotics and the number of new antibiotics expected to enter the market is limited. One of the modes by which bacteria exert this resistance is their ability to develop biofilms. Biofilms are bacterial communities encased in a hydrated polymeric matrix. Biofilm development is known to follow a series of complex but discrete and well-regulated steps (Fig. 4.1) (1) microbial attachment to the surface, (2) growth and aggregation of cells into microcolonies, (3) maturation, and (4) dissemination of progeny cells for new colony formalion (87,88). 

Biofilm formation is dynamic and can be viewed as a developmental cycle [8], beginning with microbial attachment. 

Phase imaging of microbial attachment features. Microbial attachment to mineral surfaces appears to be an important step in many forms of microbially mediated mineral dissolution (e.g., 27, 6, 7). Although the detailed mechanisms of microbially enhanced dissolution are not widely understood, it has been hypothesized that attached microorganisms may create microenvironments conducive to dissolution, through release of extracellular material (e.g., 27). Hence, characterization of microbial attachment features to mineral surfaces may provide valuable insight into the mechanisms of microbially mediated dissolution. 

TMAFM and Phase Imaging are proving to be excellent methods for the characterization of microbial attachment features. Maurice et al. and Forsythe et al. (5,... 

W. A. Corpe, Ecology of Microbial Attachment and Growth on Solid Surfaces, Proc. Symp. Microbiol. Power Plant Thermal Effluents, Iowa City, Iowa (1978), pp. 57-65. 

MBfRs depend on the ability of microorganisms to attach to the membrane surface. Several researchers have modified membranes to promote microbial attachment and retention. The methods can be classified as chemical modification of the membrane material or addition of support material onto the membrane surface. 

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