Bacterial Cell components

Naturally occurring bacterial endotoxins contain the lipid, carbohydrate, and protein makeup of the outer cell membrane of GNB (Fig. 1). However, most of the commercial endotoxin preparations have been purified by various extraction procedures and are generally free of nucleic acids, proteins, phospholipids, and other bacterial cell components. The primary chemical configuration that remains after purification is apolysaccharide structure that is covalently bound to a lipid component called Lipid A. Based on its chemical nature, which is common to various bacterial families, this substance is referred to as lipopolysaccharide (LPS). Although the terms endotoxin and LPS are often used interchangeably, most reference endotoxin standards are purified preparations that are more correctly described as LPS. 

Bacterial cell component vaccines. Rather than... 

Because laser beams can be precisely focused, it becomes possible to perform quantitative analyses on very small samples. The Raman microprobe has been used to determine analytes in single bacterial cells, components in individual panicles of smoke and fly ash, and species in microscopic inclusions in minerals. Surfaces have been examined by tuning the instrument to a given vibrational mode. This results in an image of regions on a surface where a particular bond or functional group is present. 

Finally, decomposed products are further metabolized and utilized by various microorganisms and converted into carbon dioxide, water, and bacterial cell components. 

Hehn D and Naumann D, Identification of some bacterial cell components by FT-IR spectroscopy. FEMS Microbiol Lett., 1995, 126 75—80. 

Endotoxin and Muramyl Dipeptide Derivatives. Bacterial cell wall constituents such as the Hpopolysaccharide endotoxin and muramyl dipeptide, which stimulate host defense systems, show radioprotective activity in animals (204). Although endotoxin is most effective when given - 24 h before irradiation, it provides some protection when adrninistered shortiy before and even after radiation exposure. Endotoxin s radioprotective activity is probably related to its Hpid component, and some of its properties may result from PG and leukotriene induction (204). 

In general, penicillins exert thek biological effect, as do the other -lactams, by inhibiting the synthesis of essential structural components of the bacterial cell wall. These components are absent in mammalian cells so that inhibition of the synthesis of the bacterial cell wall stmcture occurs with Htde or no effect on mammalian cell metaboHsm. Additionally, penicillins tend to be kreversible inhibitors of bacterial cell-wall synthesis and are generally bactericidal at concentrations close to thek bacteriostatic levels. Consequently penicillins have become widely used for the treatment of bacterial infections and are regarded as one of the safest and most efficacious classes of antibiotics. 

Peptidoplycans (14,16) are the primary component of bacterial cell walls. They consist of a heteropolysaccharide called murein cross-linked with short peptide chains. 

The first known 1-carboxyethyl ether of a sugar was 2-amino-3-0-[(/ )-l-carboxyethyl]-2-deoxy-D-glucose or muramic acid (37). It is a component of the polysaccharide moiety of the peptidoglycan in the bacterial cell-wall. It is partially replaced by the mamo isomer, 2-amino-3-6>-[(/ )-l-carboxy-ethyl]-2-deoxy-D-mannose, in the peptidoglycan from Micrococcus lyso-deikticus. 

Fractionation. The process by which components are extracted firm bacterial eells or from the medium in whieh the baeteria are grown and obtained in a purified form. The polysaccharide antigens of Neisseria meningitidis are separated from the bacterial cells by treatment with hexadecyltrimethylammonium bromide and those of Streptococcus pneumoniae with ethanol. The purity of an extracted material may be improved by resolubilization in a suitable solvent and precipitation. After purification, a component may be dried to a powder, stored indefinitely and, as required, incorporated into a vaccine in precisely weighed amounts at the blending stage. 

C. Nucleoside Diphosphate Sugars.—A polyprenol phosphate containing eleven isoprene units is involved in the biosynthesis of various bacterial cell-wall components.As mentioned in last year s Report, another isoprenoid phosphate, dolichol monophosphate (40), is an intermediate in sugar... 

Although a few mechanisms have so far been proposed to explain the antimicrobial properties exhibited by proanthocyanidins (e.g., inhibition of extracellular enzymes) [86], Jones et al. [83] postulated that their ability to bind bacterial cell coat polymers and their abihty to inhibit cell-associated proteolysis might be considered responsible for the observed activity (Table 1). Accordingly, despite the formation of complexes with cell coat polymers, proanthocyanidins penetrated to the cell wall in sufficient concentration to react with one or more ultra-structural components and to selectively inhibit cell wall synthesis. Decreased proteolysis in these strains may also reflect a reduction of the export of proteases from the cell in the presence of proanthocyanidins [83]. 

PTLC was also used for the separation of lipid components in pathogenic bacteria. Mycobacterium avium has a requirement for fatty acids, which can be fulfilled by palmitic or oleic acid, and these fatty acids are then incorporated into triagylglycerols [80]. PTLC was used for the separation of fatty acids and triacylglycerols in the extracts of these bacterial cells to study the lipid classes in the bacterial cells cultured under different growth conditions. 

Stability of several enzymes like proteases from thermophilic micro-organisms can be increased in aqueous-organic biphasic systems. Owusu and Cowan [67] observed a strong positive correlation between bacterial growth temperature, the thermostability of free protein extracts, and enzyme stability in aqueous-organic biphasic systems (Table 1). Enzymes, like other cell components (membranes, DNA, (RNA ribosomes), are adapted to withstand the environmental conditions under which the organism demonstrates optimal growth. 

In bacterial cells, marker compounds are present at the part per hundred to part per thousand level. In environmental samples, which represent a complex mixture of components, such markers are often present at the part per ten thousand to part per hundred thousand level. In certain clinical samples, in some instances, these markers may be present as low as parts per... 

Subsequently 36 strains of aerobic endospore-forming bacteria, consisting of six Bacillus species and one Brevibacillus species could be discriminated using cluster analysis of ESMS spectra acquired in the positive ion mode (m/z 200-2000).57 The analysis was carried out on harvested, washed bacterial cells suspended in aqueous acidic acetonitrile. The cell suspensions were infused directly into the ionization chamber of the mass spectrometer (LCT, Micromass) using a syringe pump. Replicates of the experiment were performed over a period of six months to randomize variations in the measurements due to possible confounding factors such as instrumental drift. Principal components analysis (PCA) was used to reduce the dimensionality of the data, fol-... 

Not all the cellular DNA is in the nucleus some is found in the mitochondria. In addition, mitochondria contain RNA as well as several enzymes used for protein synthesis. Interestingly, mitochond-rial RNA and DNA bear a closer resemblance to the nucleic acid of bacterial cells than they do to animal cells. For example, the rather small DNA molecule of the mitochondrion is circular and does not form nucleosomes. Its information is contained in approximately 16,500 nucleotides that func-tion in the synthesis of two ribosomal and 22 transfer RNAs (tRNAs). In addition, mitochondrial DNA codes for the synthesis of 13 proteins, all components of the respiratory chain and the oxidative phosphorylation system. Still, mitochondrial DNA does not contain sufficient information for the synthesis of all mitochondrial proteins most are coded by nuclear genes. Most mitochondrial proteins are synthesized in the cytosol from nuclear-derived messenger RNAs (mRNAs) and then transported into the mito-chondria, where they contribute to both the structural and the functional elements of this organelle. Because mitochondria are inherited cytoplasmically, an individual does not necessarily receive mitochondrial nucleic acid equally from each parent. In fact, mito-chondria are inherited maternally. 

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