Bacteria and Other Microorganisms

Mercury-tolerant strains of bacteria and protozoa have been reported. Mercury-resistant strains of bacteria are common. In Chesapeake Bay, for example, at least 364 strains of bacteria that were isolated were resistant to HgCb. Most were pseudomonads, and almost all were from seven genera. Other groups of bacteria known to materially influence mercury fluxes in saline waters include strains of Escherichia coli that convert Hg + to Hg, and strains of anaerobic methanogenic bacteria that enhance the transfer of methylcobalamin to Hg + under mild reducing conditions. Some mercury-resistant strains were reported to degrade petroleum as well. Mercury-resistant strains of bacteria have been recommended as bioindicators of environmental mercury contamination and as markers of methylmercury in biological samples. The mercury-resistant 

Some species of mushrooms have been recommended as sentinel species of mercury contamination because of their ability to accumulate very high concentrations of mercury from the ambient air. In one study, shiitake mushrooms, Lentinus edodus, exposed to Hg vapor at 172.0 xg Hg/m for up to 7 days had grossly elevated concentrations of mercury in caps and stalks. After 3 days caps had 125.0 mg Hg/kg DW and stalks 10.0 mg Hg/kg DW. After 7 days, these values were 310.0 00.0 mg/kg DW in caps and 20.0-30.0 mg/kg DW in stalks. 

Methylmercury compounds have induced abnormal sex chromosomes in the fruit fly Drosophila melanogaster). Earthworms (Eisenia foetida) exposed to soil containing 

Using artificial ecosystems, reduced initial growth of natural ph54oplankton from Saanach Inlet, British Coluinbia, Canada, was noted after addition of 1.0-5.0 p,g Hg/L however, recovery to above control levels appeared to occur in 21 days. 

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Germicidal Properties. The germicidal activity of aqueous chlorine is attributed primarily to HOCl. Although the detailed mechanism by which HOCl kills bacteria and other microorganisms has not been estabUshed, sufficient experimental evidence has been obtained to suggest strongly that the mode of action involves penetration of the cell wall followed by reaction with the enzymatic system. The efficiency of destmction is affected by temperature, time of contact, pH, and type and concentration of organisms (177). 

Process Description Microfiltration (MF) separates particles from true solutions, be they liquid or gas phase. Alone among the membrane processes, microfiltration may be accomplished without the use of a membrane. The usual materi s retained by a microfiltra-tion membrane range in size from several [Lm down to 0.2 [Lm. At the low end of this spectrum, very large soluble macromolecules are retained by a microfilter. Bacteria and other microorganisms are a particularly important class of particles retained by MF membranes. Among membrane processes, dead-end filtration is uniquely common to MF, but cross-flow configurations are often used. 

Like living organisms themselves, cells come in a remarkable variety of flavors. Brown has described what might be a human cell with elaborate internal structure. However, there is no such a thing as a typical cell. Afunctional liver cell, a hepatocyte, is quite distinct from a nerve cell, a neuron, that, in turn, is not much like a cell of the retina of the eye. Skin cells, pancreatic cells, kidney cells, cells of the testis and ovary, red blood cells, bone cells, and on and on, are all structurally, functionally, and metabolically distinct. Indeed, there are several types of cells in the skin, pancreas, kidney, testis, ovary, and bone. Then there are the cells of bacteria and other microorganisms that have no nucleus or other membrane-limited organelles very different. Diversity abounds. 

The skin is a soft outer covering of an animal in particular, a vertebrate. It is the body s first defense against the elements, be it rain, sun, cold, bacteria and other microorganisms, or simple cuts and scrapes. The skin protects the rest of the body by putting itself in the line of fire. Under these circumstances, it is no wonder that skin ailments are such a common occurrence. Any ailment that affects the skin is known as a skin disease. In scientific terminology, all skin diseases are referred to as dermatosis. 

Introduce biological agents to the spill to hasten biodegradation. Most of the components of oil washed up along a shoreline can be broken down by bacteria and other microorganisms into harmless substances such as fatty acids and carbon dioxide. This action is called biodegradation. Oil... 

Chlorine dioxide is added to drinking water to protect people from harmful bacteria and other microorganisms. Most people will be exposed to chlorine dioxide and its disinfection by-product, chlorite ions, when they drink water that has been treated with chlorine dioxide. The EPA has set the maximum concentration of chlorine dioxide and chlorite ion in drinking water at 0.8 and 1.0 milligrams per liter (mg/L), respectively. However, the concentrations of chlorine dioxide and chlorite ion in your drinking water may be lower or higher than these levels. For additional information about how you might be exposed to chlorine dioxide and chlorite, see Chapter 6. 

What the people saw were various bacteria and other microorganisms, not the viruses that cause influenza. Still, Katterfelto was on the right track when he linked microbes to disease. After being terrified by these tiny active creatures invisible to the naked eye, audience members were treated to Katterfelto s hocus-pocus, his black cat, and his scientific tricks. They were astonished, and they readily concluded that the strange man in... 

Interesting areas of application are not only hand dryers, soap dispensers or entire sanitary units in public washroom facilities, but in general articles that come into contact with bacteria and other microorganisms and that need to be sterile. These include hospital beds, medical treatment chairs or computer keyboards in public offices. 

Gadd, G. M. (1990b). Heavy metal accumulation by bacteria and other microorganisms. Experientia, 46, 834-40. 

Siderophores. If a suitably high content of iron (e.g., 50 pM or more for E. coli) is maintained in the external medium, bacteria and other microorganisms have little problem with uptake of iron. However, when the external iron concentration is low, special compounds called siderophores are utilized to render the iron more soluble.7 11 For example, at iron concentrations below 2 pM, E. coli and other enterobacteria secrete large amounts of enterobactin (Fig. 16-1). The stable Fe3+-enterobactin complex is taken up by a transport system that involves receptors on the outer bacterial membrane.9 12 13 Siderophores from many bacteria have in common with enterobactin the presence of catechol (orftzo-dihydroxybenzene) groups... 

What kills the ingested bacteria and other microorganisms Although superoxide anion is relatively unreactive, its protonated form HCV, is very reactive. Since its pKa is 4.8, there will be small amounts present even at neutral pH. Some of the 02 may react with... 

A variety of bacteria and other microorganisms, such as the archaeum Ferriplasma acidarmanus, may be actively involved in the oxidation of arsenopyrite (Gihring et al., 1999 Cruz et al., 2005 Barrett et al., 1993). Specifically, (Gihring et al., 1999) collected Thiobacillus caldus and Ferriplasma acidarmanus from acid mine drainage at Iron Mountain, California, USA. The mine drainage had a temperature of approximately 42 °C, a pH of 0.7, and contained about 50 mg L 1 of arsenic. T. caldus growths on the surfaces of arsenopyrite actually hindered the oxidation of the mineral, whereas F. acidarmanus was very tolerant of arsenic and accelerated the dissolution of arsenopyrite (Gihring et al., 1999). 

Rather than using expensive and possibly toxic chemicals, certain bacteria and other microorganisms have the ability to oxidize As(III) in water, wastes, soils, and sediments (Ehrlich, 2002 Santini, Vanden Hoven and Macy, 2002 Anderson et al., 2002). Microbacterium lacticum (Mokashi and Paknikar, 2002) and Alcaligenes faecalis (Anderson et al., 2002) are examples of bacteria that are known to oxidize As(III). Some bacteria use As(III) as a source of energy, whereas others simply oxidize it as a means of detoxifying their environments (Ehrlich, 2002, 313). 

Belozersky, 1958,1959 Konovalov, 1960) or 10 % perchloric acid, at 80-100 °C (Krishnan etal, 1957 Drews, 1960b Fedorov, 1961 Harold, 1960,1962ab lames andCasida, 1964). When this method of extraction was employed, the condensed phosphates are hydrolysed to orthophosphate, the amount of which indicates the amount of condensed phosphates present in the acid-insoluble fraction. Hughes and co-workers (Hughes et al, 1963) used a prolonged (5 h) extraction of acid-insoluble PolyPs with 10 % TCA at 20-22 °C. In the author s opinion, this method ensures an almost complete extraction of acid-insoluble PolyPs from the cells of bacteria and other microorganisms. 

D. E. Hughes, Brit. J. Exp. Pathol., 32 97 (1951). A Press for Disrupting Bacteria and Other Microorganisms. 

Figure 25.3 Viruses, bacteria, and other microorganisms in plankton (left) from Southern California and from sediments (right) from Florida Bay. Note bacterial morphological diversity is greater in sediments than in the water column but viruses and bacteria are harder to distinguish from detritus.

By using theory and experimental results concerning particle deposition in porous media, predictions can be made of the removal of viruses, bacteria, and other microorganisms in aquifers. For a clean aquifer (i.e., one that has not received significant inputs of colloidal particles), the effects of particle size and surface chemistry on colloid transport are illustrated in Figure 11. The travel distance required to deposit 99% of the particles in a suspension (L99) is plotted as a function of the size (radius) of those particles for two chemical conditions. 

Microbiologically polluted water contains bacteria and other microorganisms that may be hazardous or toxic. Human and animal wastes from sewage and farmyard runoff are the principal sources of microbiological pollution. Polluted water can be an indirect hazard, as fish and shellfish may become contaminated and eaten. 

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