Cell Surface of Bacteria

D-Manp is D-mannopyranosyl L-Rhap is L-rahmnopyranosyl D-GalA is D-galactopyranosyluronic acid 0-GlcA is D-glucopyranosyluronic acid Hep is L-g[ycero-D-manno-heptopyranose 

KDO is 3-deoxy-p-D-manno-octopyranulosonic acid residue R is an acyl group of a long chain tty acid such as lauric, palmitic, etc. Rl is-CaCH2-CH(OH)-(CH2)io-CH3 

Few pyrolysis studies were performed on particular components of bacterial lipopolysaccharides. Py-MS results on KDO were reported [3]. The Py-MS studies on individual lipopolysaccharides may encounter problems caused by the difficulty of obtaining pure compounds from this class. As previously indicated, a significant amount of work has been done on direct Py-MS of a variety of whole microorganisms with the purpose of their rapid identification and classification [3]. 

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Mahon (1982) measured BCFs of 1,576 and 459 in algae and plankton, respectively. Horikoshi et al. (1981) determined BCFs in several species of bacteria that ranged from 2,794 to 354,000. However, bioconcentration by the bacteria represented adsorption onto the cell surfaces of the bacteria rather than true biological uptake. 

Bioremediation of sites that are contaminated with toxic metals is an important issue in environmental restoration. Bacteria have long been known for their ability to Itake up metals from their immediate environment (Borrok and Fein 2004). The efficiency of bacterial cells in concentrating metals is related to their large surface area-to-volume ratio and high surface density of charge. The cell surfaces of all bacteria are negatively... 

The removal of Pb by Brevibacterium sp strain PBZ was markedly enhanced by the presence of glucose (Simine et al. 1998). Desorption of the metal by EDTA restored the binding capacity of the cells. U(VI) could be desorped from the cell surface of B. cereus by citric acid or sodium bicarbonate with the formation of water-soluble complexes although U(VI) was strongly bound on the cell surface of the bacteria. However, uranyl in... 

Bacteria and their composites with soil minerals or organic matter are capable of taking up a wide range and variety of toxic metals in soil environments. Research done over the last decade or so has greatly improved our understanding of the mechanisms on biosorption of metals and bacte-ria-metal-soil component interactions. However, more studies from molecular level are needed in order to enhance the ability of bacteria and their association with soil components to remediate toxic metals-contaminated soils. The focus of future investigations should be on the mechanisms by which metals are sorbed and bound by bacterial cell surfaces and bacteria-soil/mineral composites. In this connection, X-ray absorption spectroscopy (XAS) is a promising technique because it can provide information about... 

The reduction of U(VI) by sulfate-reducing bacteria appears to occur at the cell surface of the anaerobes, since the reduced products of these elements accumulates in the environment outside of the cell. The proteins of cyt Cs and cyt c have been demonstrated to function as nonspecific metal dehydrogenases however, these cytochromes are found in the periplasm and not in the outer membrane. Thus, if it were analogous to Fe(III) reduction, uranyl ions would most appropriately be reduced by a cytochrome in the outer membrane of the sulfate reducers. As demonstrated by Laishley and Bryant (see Chapter 18) cytochromes are located in the outer membrane of certain sulfate reducers however, their role in reduction of U(VI) remains to be demonstrated. 

Lectin pathway, stimulated by binding to a lectin. Lectins belong to a family of proteins called collectins, which are present in blood and bind to bacteria. One lectin, known as the mannose binding lectin (MBL), binds to a sequence of mannose sugars that are part of the carbohydrate on the cell surface of some bacteria. It is the lectin-bacteria complex that activates one of the complement proteins. The components of the pathway are prefixed with a C and a number. 

All minerals in [VI] are found as selectively precipitated minerals on the surface of bacteria cells... 

The outer surfaces of bacteria are rich in specialized polysaccharides. These are often synthesized while attached to lipid membrane anchors as indicated in a general way in Eq. 20-20.136/296a One of the specific biosynthetic cycles (Fig. 20-9) that depends upon undeca-prenol phosphate is the formation of the peptidoglycan (murein) layer (Fig. 8-29) of both gram-negative and gram-positive bacterial cell walls. Synthesis begins with attachment of L-alanine to the OH of the lactyl... 

LPSs carry the major immunogenic determinants on the cell surface of Gram-negative bacteria and, in many instances, serve as the basis for their serological classification. In this section, contribution of LPSs that contain 5,7-diamino-3,5,7,9-tetradeoxynon-2-ulosonic acids to the immunospecificity and serological classification of two human pathogens, viz. L. pneumophila and P. aeruginosa, are reviewed. 

Therefore, another possibility in animal studies is to wash out the upper jejunum with a small volume of bicarbonate buffer, and use this fluid as a medium to determine the stability of a test macromolecule or formulation. A similar approach can be used to study enzyme activities in the colon in animals. It should be noted that the preparations should not be centrifuged, but used in their entirety as enzymes can bind to particulate matter or are on the surfaces of bacteria in the case of colon contents (Woodley 1991). Fluid thus obtained from the upper intestine should contain all the pancreatic enzymes, bile salts and sloughed-off cells, but again getting the concentrations right is not obvious. 

Host cells targeted by endotoxin on the surface of bacteria have developed defense mechanisms for protection against gram-negative bacteria. The first line... 

The cell envelopes of bacteria play an essential role in bacterial virulence, surface attachment and biofilm formation (O Toole et al, 2000). This cell compartment possesses PolyPs, and thereby its role in the above functions was intensively investigated. The conclusion was... 

Plasmid R124 alters the cell surface of E. coli cells such that they show enhanced resistance to the QAC, cetrimide, and other agents [299]. Generally, plasmids do not promote resistance in Gram-negative bacteria to biocidal agents [300], although hospital isolates may be more resistant to biocides than laboratory strains [301]. It is to be wondered whether an Mdr system is associated with this resistance. 

Numerous factors influence the bioaccumulation of uranium, such as the chemical and physical form of the uranium the season of the year and other climatic factors such as temperature, age of the organism, specific tissue or organs involved and the specific characteristics of the local ecosystem, such as total suspended and dissolved solids. Bioconcentration factors for uranium have been measured by several investigators in various aquatic organisms. Mahon (1982) measured bioconcentration factors of 1,576 and 459 in algae and plankton, respectively. Horikoshi et al. (1981) determined bioconcentration factors in several species of bacteria that ranged from 2,794 to 354,000. However, bioconcentration by the bacteria represented adsorption onto the cell surfaces of the bacteria rather than true biological uptake. 

Fig. 11.1 Imprinting of bacterial cells. Aqueous pre-polymers with attached affinity ligands (L) bind to bacteria. Introduction of an organic phase containing a diacid chloride and partitioning of the pre-polymer/cell complex to the interface results in polymerisation at and around the surface of bacteria.

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