Presence of Microbes

Microbes are present almost everywhere in soils, freshwater, seawater, and air. However, the mere detection of microorganisms in an environment does not necessarily indicate a corrosion problem. Nonetheless, it is well-established that numerous buried steel pipes have suffered severe corrosion as the result of bacterial action. 

In unaerated or anaerobic soils, this attack is attributed to the influence of the sulfate-reducing bacteria (SRB). The mechanism is believed to involve both direct attack of the steel by hydrogen sulfide and cathodic depolarization aided by the presence of bacteria. Even in aerated or aerobic soils, there are sufficiently large variations in aeration that the action of SRB cannot be neglected. For example, within active corrosion pits, the oxygen content becomes exceedingly low. 

Bacteria, fungi, and other microorganisms can play a major part in soil corrosion. Spectacularly rapid corrosion failures have been observed in soil due to microbial action and it is becoming increasingly apparent that most metallic alloys are susceptible to some form of microbiologically influenced corrosion (MIC). 

The presence of aggressive microbes may also be quite severe in industrial water-handling systems, for example, cooling water and injection water systems, heat exchangers, wastewater treatment facilities, storage tanks, piping systems, and all manner of power plants, including those based on fossil fuels, hydroelectric, and nuclear [8]. Table 7.2 lists potential problem areas by industry [9]. 

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Our isolation techniques should begin with steps that might be expected to operate in nature. Usually, water will be the appropriate solvent. We should perform isolation in the absence and presence of microbes to see if they add new toxins. 

Endotoxin, which is due to the presence of microbes Organic and inorganic impurities... 

Shulze-Makuch and Irwin also suggest that the presence of microbes may explain the unexpectedly low concentration of carbon monoxide in the Venusian atmosphere. One would normally expect a greater abundance of this gas, they say, because lightning and solar radiation tend to break down carbon dioxide into carbon monoxide and other products perhaps microbes have evolved a mechanism for using carbon monoxide as a raw material in their metabolism. Shulze-Makuch and Irwin are hoping that ESA s Venus Express mission will provide additional data that will help resolve the question of whether even the simplest form of life can exist on Venus. 

This dye exists in nature in three crystalline forms—anatase, brookite, and rutile—however, only one is used as an additive). It possesses an intense white color, is resistant to sunlight, oxidation, pH, and the presence of microbes. Only the synthetically produced titanium dioxide can be used as a food additive. This dye cannot be dissolved in all solvents. The allowed quantity of dye in foods is up to 1% and can be used in confectionery products in the formation of white parts as well as a background. Finally, it can be used in the production of pills and cosmetics. 

Ethanol is a molecule you are probably familiar with it s the alcohol found in alcoholic beverages that makes you feel intoxicated, and humans have consumed it for hundreds of years. Additionally, it is useful as a solvent, an antiseptic, a sedative, and a component in perfumes, lacquers, cosmetics, aerosols, antifreeze, and mouthwash. Ethanol can be produced from a raw feedstock, like corn or grain, by fermenting it in the presence of microbes, which can readily digest sugars and produce ethanol as a byproduct. 

Reproducible processing conditions, leading to improved quality control and optimization of the yield(s) of the desired product(s). Cultured cells would be free from the presence of microbes and insects. 

Fig. 2.26 Recoveries of g-coumaric add from the bottom of Cecil A soil columns in the presence of cucumber seedlings and microbes (a), in the absence of microbes and seedlings (b), and in the presence of microbes but absence of seedlings (c). For (a), approximately 25, 50 or 95 [xg/ml of p-coumaric acid in 25% Hoagland s nutrient solution was applied to the columns at a rate of 2-3.5 ml/h. For (b) and (c), 41 and 54 jjig/ml, respectively, of p-coumaric acid in different nutrient solution concentrations (0-50%) was apphed to columns at the same rate as in (a). Figures reproduced from Blum et al. (1999a). Cddiz Univ Press, Puerto Real. Figures used with permission of Servicio de Publicaciones Universidad De Cadiz...

The biodegradable packaging industry demands a matching or superiority in physical and chemical properties of biodegradable polymers with their synthetic counterparts. Starch mixed with polyethene is also known as biobased [hydrodegradahle) material. Microbial breakdown is controlled by the polymers that use starch, for example, PLA, PCL, and PVA. They allow breakdown in the presence of microbes, heat, moisture, and proper aeration, as found in traditional compost piles. Additive-based plastic bags are the traditional plastic bag films, whereas special chemical modification is used to make them break down under certain conditions. 

FIG. 1-1 A worker at the SteriGenics irradiation faciiity in TusUn, Caiif., loads drums of spices onto carriers that wiii be transported to an irradiation ceii to reduce the presence of microbes in the food. (Source Keeping Food Germ Free. )... 

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