Bacteria cell components

Finally, a novel process has been described for efficient photoconversion of low-grade organic materials such as waste biomass into polyesters. In this process, dry biomass has been thermally gasified which resulted in gas mixtures composed primarily of CO and H2. Photosynthetic bacteria photoassimilated components of the synthesized gas into new cell mass. Under unbalanced culture conditions, when growth was limited by several nutrients, up to 28 % of the new biomass was found to be poly(3HB) [37]. 

Lysosomes and peroxisomes These organelles are the recycling center of the cell. They digest foreign bacteria that invade the cell, rid the cell of toxic substances, and recycle worn-out cell components. 

Cell components or metabolites capable of recognizing individual and specific molecules can be used as the sensory elements in molecular sensors [11]. The sensors may be enzymes, sequences of nucleic acids (RNA or DNA), antibodies, polysaccharides, or other reporter molecules. Antibodies, specific for a microorganism used in the biotreatment, can be coupled to fluorochromes to increase sensitivity of detection. Such antibodies are useful in monitoring the fate of bacteria released into the environment for the treatment of a polluted site. Fluorescent or enzyme-linked immunoassays have been derived and can be used for a variety of contaminants, including pesticides and chlorinated polycyclic hydrocarbons. Enzymes specific for pollutants and attached to matrices detecting interactions between enzyme and pollutant are used in online biosensors of water and gas biotreatment [20,21]. 

Membrane teichoic acids have now been detected in a large number of bacteria, including almost all of the Gram-positive organisms examined. Nevertheless, the proportion present is sometimes small, and separation of the acids from other macromolecular cell-components, such as nucleic acids, peptides, and polysaccharides, is difficult. Consequently, few have been obtained in an amount and of a purity adequate for detailed chemical study. Even from the limited studies so far made, it is clear that structural details differ considerably from case to case, and it is convenient to classify these teichoic acids according to the organisms from which they have been isolated. 

A possible application for nanotubes (see Section 16.2) is in the sensing and decontamination of chemical and biological weapons. Preliminary results [976] show that some lipid nanotubes change colour when exposed to model chemical weapon components and bacteria, and that they may be able to reduce the concentrations of bacteria. Figure 16.5 shows nanotubes adsorbing onto and even piercing an Escherichia coli bacteria cell. 

The chief culprits in generating armpit odours are the bacteria Corynebacterium xerosis and Micrococcus luteus, with Staphylococcus epidermis and Staphylococcus aureus playing minor roles. There can be as many as ten million bacteria cells per square centimetre of armpit skin compared to only 1,000 on the skin of the forearm, and this is as true for women s armpits as for men s, and yet the odour women give off is different because it lacks some of the ingredients that male sweat contains. Male underarm odour has three components an acrid one, a musky one, and a pungent one. The first of these comes from short-to-medium chain acids, the second from steroid type molecules, and especially androstenone, and the third from sulfur-containing molecules. 

The major use of inositol in bacteria is in generating Pis, versatile membrane components that can be derivatized to anchor proteins or complex carbohydrates to the cell surface. In some microorganisms, the complex carbohydrate structure attached to the PI anchor in the cell envelope is part of the way the microorganism recognizes or binds to target cell components. 

In addition to extracellular polysaccharides, biofilms contain proteins, DNA and RNA, as well as peptidoglycan, lipids, phospholipids and other cell components. Some of these materials are secreted by the bacteria, while others are products from cell lysis, or environmental material [316,319]. Biofilms are highly hydrated, and up to 97% of the biofilm can be made of water [320]. Confocal scanning laser microscopy has shown that cells within biofilms are aggregated into microcolonies separated by channels that allow the passage of nutrients and waste products [316]. 

The surface of the bacterial cell is the portion of the organism that interacts with the external environment most directly. As a consequence, many bacteria deploy components on their surfaces in a variety of ways that allow them to withstand and survive fluctuations in the growth environment. The following sections describe a few of these components that are commonly found, although not universally, that allow bacteria to move, sense their environment, attach to surfaces and provide protection from harsh conditions. 

Polysaccharides are found in plants and animals. In higher plants and algae, they are components of either the cell wall or the cell interior. In bacteria and fungi, they can be both cell components and metabolic products. Consequently, in addition to classification according to their chemical structure, polysaccharides are often classified according to their function or use ... 

For the biosynthesis of cell components a microorganism must be supplied with appropriate low molecular weight compounds such as sugars, organic acids, amino acids etc. Many of 2-, 3-, 4- and 5-carbon compounds are formed in catabolic reactions. In propionic acid bacteria these reactions comprise the propionic acid fermentation, TCA cycle and hexose monophosphate shunt. The latter supplies the cell with erythrose-phosphate, ribose-5-phosphate and reducing equivalents (NADPH) needed for many syntheses. Erythrose-4-phosphate is used in the formation of aromatic amino acids phenylalanine, tryptophane, tyrosine. Ribose-5-phosphate is incorporated into nucleic acids. The pentose cycle and propionic acid fermentation, as mentioned before, have a number of common precursors and enzymes. The inclusion of common precursors into one or another pathway is regulated by the level of ATP (Labory, 1970), and this regulation in fact determines the ratio of catabolic and anabolic processes in the cell. 

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