Bacterial cell surfaces, alteration

The proposed mechanism of action is by alteration of bacterial cell surfaces so that aggregation and attachment is reduced. 

A biological compound (an enzyme, usually) intended to improve the response of an electrode can be incorporated into it in two ways, namely (a) by altering the sensing surface in order to accommodate the biocatalysts [i.e. by constructing a (bio)chemically modified electrode] and (h) by using a membrane place in front of the surface electrode in order to trap the enzyme. The enzyme can be used in isolation (most often in a commercially available form) or be part of a tissue material or bacterial cells. 

Bioleaching is an application of mineral alteration under the action of microorganisms. The combination of molecular biology, reflectance microscopy, and XPS demonstrated that reduction of Fe ) oxides under the influence of Geobacter sul-furreducens could be related to the expression of specific genes by individual bacterial cells and cell aggregates associated with the mineral surface. Mineral transformation by G. pelophilus was also demonstrated to be mediated by the surface asso-... 

As surfactants alter the permeability of mammalian cells it is not too surprising that, in spite of the differences between bacterial cell walls and mammalian cell membranes, some surfactants have the ability to increase the permeability of the bacterial cell wall or to act synergistically with antibacterial agents. There are several unique facets to discussion of this topic some surfactants have antibacterial properties and some antibacterial agents have surface-active properties. In considering the subject one has to be aware, as before, of surfactant antibacterial interactions, the influence of surfactant on the performance of the dosage form or formulation, and surfactant-cell wall interactions. 

Most bacterial cells are characterized by a tough, rigid cell wall (31). In some instances it is possible to isolate proteins from the cell surface or interior by simple extraction procedures without first breaking the cell wall. Thus M" protein can be extracted from hemolytic streptococci with i T/20 hydrochloric acid at 37°C. (Lancefield, 75) and T protein by treatment of the cells with pepsin at pH 2.5 for 6-12 hours (Lancefield and Dole, 78). Although some chemical alteration may be caused by such rather drastic procedures, M and T proteins extracted in this manner exhibit serological behavior similar to that shown in the intact cell. 

Although ribosomal proteins are readily observed as in Figures 13.7 and 13.8 altered matrix conditions can alter the relative ionization of bacterial whole-cell compounds. A systematic analysis involving laser power/fluence and sample preparation conditions reveals that if the concentrated trifluo-roacetic acid is added and the laser power increased above optimal conditions, ionization of bacterial surface compounds can be enhanced. Figure 13.9 is the resulting 9.4 T MALDI-FTMS, seen are both the Braun s lipoprotein56,57 and the Murein lipoprotein. Both of these compounds are complex combinations of hydrocarbon lipids attached to a protein base. This is the first MALDI-FTMS observation of surface proteins desorbed directly from whole cells by influencing ionization conditions. 

---