Bacteria bacterium

From the table it is obvious that compounds XVIII, XIX, XX, XXIII depress growth and development of plant pathogenic bacteria Bacterium tumefaciens, Xanthomonas campestris. It must be noted that compounds XVIII, XIX, XX, XXIII don t reveal activity towards Streptomyces allbogriseolus subsp, Aragvi zone of depression doesn t exceed 1,0 mm (see table 2). 

There are two convenient forms of genetic material, that can be used as vehicles for introducing the new gene into the bacterium a small circular DNA piece, called a plasmid, or a virus that grows in bacteria. The techniques described below apply to both plasmids and viruses. 

Taq polymerase was first found in a bacterium Ther mus aquaticus) that lives in hot springs in Yellowstone National Park Bacteria of this type are called ther mophiles because they thrive in warm environments... 

Some chemicals such as iadigo, tryptophan, and phenylalanine are overproduced ia bacteria by pathway engineering (36—38). In this method, the enzymes iavolved ia the entire pathway are overproduced. In addition, the host bacterium is also altered such that the carbon flow is directed toward the engiaeered pathway (38). E. colih.2LS been modified to overproduce iadigo and tryptophan and phenylalanine. CoTjnebacteriumglutamicum has been engiaeered to overproduce tryptophan from 28 to 43 g/L. Similarly, attempts are underway to overproduce several vitamins by pathway engineering (34,38). 

Live vaccines are normally weakened strains that do not cause diseases in the host, but stiU can stimulate the immune response. A typical example is the poho vaccine. The weakening of microorganisms or attenuation of the vims or bacteria can be accompHshed by passage through different substrates and/or at different temperatures. Modem genetic engineering techniques can also be used to attenuate a vims or bacterium. 

Animals cannot synthesize vitamin A-active compounds and necessary quantities are obtained by ingestion of vitamin A or by consumption of appropriate provitamin A compounds such as P-carotene. Carotenoids are manufactured exclusively by plants and photosynthetic bacteria. Until the discovery of vitamin A in the purple bacterium Halobacterium halobium in the 1970s, vitamin A was thought to be confined to only the animal kingdom (56). Table 4 Hsts RDA and U.S. RDA for vitamin A (67). 

A fermentation route to 1-butanol based on carbon monoxide employing the anaerobic bacterium, Butyribacterium methjlotrophicum has been reported (14,15). In contrast to other commercial catalytic processes for converting synthesis gas to alcohols, the new process is insensitive to sulfur contaminants. Current productivities to butanol are 1 g/L, about 10% of that required for commercial viabiUty. Researchers hope to learn enough about the bacteria s control mechanisms to be able to use recombinant DNA to make the cells produce more butanol. 

Acid producers. Many bacteria produce acids. Acids may be organic or inorganic depending on the specific bacterium. In either case, the acids produced lower the pH, usually accelerating attack. Although many kinds of bacteria may generate acids, Thiobacillus thiooxidans and Clostridium species have most often been linked to accelerated corrosion on steel. 

Nitrobacter, an aerobic bacterium, can materially depress pH by oxidizing nitrite (NO2 ) to nitrate (NOa ), in effect producing nitric acid. Acidity may increase until pH is between 3 and 5. Such bacteria require high concentrations of oxygen and cause problems only in oxygenated systems. 

Certain strains of Escherichia coli can be stimulated by irradiation with a moderate dose of ultraviolet (UV) light to stop normal growth and start producing bacteriophages that eventually lyse the bacterium. Bacteria of these so-called lysogenic strains carry the DNA of the phage integrated into their own... 

Bacteria are named according to a binomial system. The first word is the genus and the second is the species name. The most frequently referred to bacterium in the sanitary field is Escherichia coli. E. coli is a common coliform that can be used as an indicator of water s bacteriological quality. Under a microscope and magnified 1,000 times, cells appear as individual short rods. 

As recently as 1970, only about 30 naturally occurring organohalogen compounds were known. It was simply assumed that chloroform, halogenated phenols, chlorinated aromatic compounds called PCBs, and other such substances found in the environment were industrial pollutants. Now, only a third of a century later, the situation js quite different. More than 5000 organohalogen compounds have been found to occur naturally, and tens of thousands more surely exist. From a simple compound like chloromethane to an extremely complex one like vancomycin, a remarkably diverse range of organohalogen compounds exists in plants, bacteria, and animals. Many even have valuable physiological activity. Vancomycin, for instance, is a powerful antibiotic produced by the bacterium Amycolatopsis orientalis and used clinically to treat methicillin-resistant Staphylococcus aureus (MRSA). 

FIGURE 19.27 A DNA molecule is very large, even in bacteria. In this micrograph, a DNA molecule has spilled out through the damaged cell wall of a bacterium. 

Even entrapment of entire cells within reversed micelles without loss of their functionality has been achieved. For example, mitochondria and bacteria (Actinobacter cal-coaceticus, Escherichia coli, Corynebacterium equi) have been successfully solubilized in a microemulsion consisting of isopropyl pahnitate, polyoxyethylene sorbitan trioleate [162], Enhanced hydrogen photoproduction by the bacterium Rhodopseudomonas sphaeroides or by the coupled system Halobacterium halobium and chloroplasts organelles entrapped inside the aqueous core of reversed micelles with respect to the same cells suspended in normal aqueous medium has been reported [183,184],... 

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