Contamination bacterial

Biodegradable drilling fluid formulations have been suggested. These are formulations of a polysaccharide in a concentration insufficient to permit a contaminating bacterial proliferation, namely a high-viscosity carboxymethyl-cellulose sensitive to bacterial enzymes produced by the degradation of the polysaccharide [1419]. 

A microbial contacting process for the oxidation of H2S was disclosed [22], in which a chemoautotrophic bacterium T. thiooxidants or T. ferroxidans) is used to remove sulfides from gaseous streams, at aerobic conditions and low pH. The low pH is preferred since the optimum pH for growth of the bacteria is below 4.0. and for the elimination of undesired contaminant bacterial strains. A contactor is employed, the flow of the sulfur-containing stream is contacted counter-currently with the biocatalytic aqueous solution. The sulfate is recovered from the aqueous solution, which contains the biocatalyst, as well. 

Finally, suppression of the contaminating bacterial flora represents the major aim of treatment for SIBO. 

The reaction velocity constant k in min for the contaminating bacterial spores can be represented as (A 1)... 

The soil or matrix material was removed from the tubes in a sterilized laminar flow hood. The profile was divided into 6 zones that were designated as A (surface soil, from 0- to 0.3-m), B (soil from the B horizon, from 0.31 to 1.2-m), Cl (soil from the C horizon, from 1.4- to 3.5-m), C2 (soil from the C horizon, from 3.6- to 5.0-m), F (aquifer matrix material recovered just above the saturated zone, from 5.2- to 6.6-m) and S (aquifer matrix material from die saturated zone, from 6.8- to 8.8-m). All equipment used in this study was autoclaved or surface sterilized prior to use to prevent contamination. Bacterial counts were similar throughout the soil profile ranging from 8.47 to 7.98 log bacteria/g for the A and F zones, respectively (19). The number of fungal organisms, however, differed by orders of magnitude in the profile, from 6.81 to 1.28 log fungi/g for A and S zones, respectively. 

EMCs are generally manufactured from cheese pastes that are made from the cheese of the same type. Additional components such as butterfat or cream may be added to add extra precursors when appropriate. Noncheese ingredients such as MSG, yeast extract, diacetyl, or other flavorants may also be added, but they may have to be declared on the label of the final product. Consistency in this base material is critical to the production of a standardized EMC product. Off-flavors may develop during incubation of the paste/enzyme slurry since the conditions are optimal for microbial growth. Equipment must be sterilized and precautions taken to prohibit miCTobial contamination. Bacterial inhibitors such as nitrates, sorbate, or nicin may be used. Free fatty acids generated by lipase enzymes afford some inhibition. Incubation time and temperature influence enzyme action and must be carefully controlled. 

Phytoremediation is also being developed for dealing with soils contaminated with high levels of selenium in California again B.juncea seems to be particularly effective in accumulating the contaminant from soil, and all plants tested were more effective at removing selenate than selenite (92). This is an interesting contrast to bacterial systems, where selenite reduction is more commonly found than selenate reduction. 

The separation of cells from the culture media or fermentation broth is the first step in a bioproduct recovery sequence. Whereas centrifugation is common for recombinant bacterial cells (see Centrifugal separation), the final removal of CHO cells utilizes sterile-filtration techniques. Safety concerns with respect to contamination of the product with CHO cells were addressed by confirming the absence of cells in the product, and their relative noninfectivity with respect to immune competent rodents injected with a large number of CHO cells. 

Resistance to antimicrobial agents is of concern as it is well known that bacterial resistance to antibiotics can develop. Many bacteria already derive some nonspecific resistance to biocides through morphological features such as thek cell wall. Bacterial populations present as part of a biofilm have achieved additional resistance owkig to the more complex and thicker nature of the biofilm. A system contaminated with a biofilm population can requke several orders of magnitude more chlorine to achieve control than unassociated bacteria of the same species. A second type of resistance is attributed to chemical deactivation of the biocide. This deactivation resistance to the strong oxidising biocides probably will not occur (27). 

An industrial fermentor of capacity up to several hundred kiloliters equipped with aeration and stirring devices, as well as other automatic control systems, is used. The cultures must be sterilized and aseptic air must be used owing to the high sensitivity to bacterial contamination of L-glutamic acid fermentation. 

Clinical manifestation of vitamin B 2 deficiency is usually a result of absence of the gastric absorptive (intrinsic) factor. Dietary deficiency of vitamin B 2 is uncommon and may take 20 to 30 years to develop, even in healthy adults who foUow a strict vegetarian regimen. An effective enterohepatic recycling of the vitamin plus small amounts from bacterial sources and other contaminants greatly minimizes the risk of a complete dietary deficiency. Individuals who have a defect in vitamin B 2 absorption, however, may develop a deficiency within three to seven years. 

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