Concentrating bacteria

Products of higher plants and animals in high concentration, bacteria in relatively low concentration... 

To remove non-bacterial ATP, force-meat suspension was filtered through luminometric polystyrene microcuvette (h 13 mm, 0 10 mm) with the bottom made of bacterial membrane filter (pore size 0.45 pm), Filtravette . Application of Filtravette permits to concentrate bacteria cells, extract bacterial ATP and measure bioluminescent signal in the same cuvette. As a result, the assay simplifies, its accuracy enhances and detection limit of bacteria cells increases. 

Original bacteria concentration Bacteria coneentration after 5 s of DBD treatment Baeteria eoneentration after 10 s of DBD treatment Bacteria concentration after 15 s of DBD treatment... 

Rosenblatt et al. (1975) reviewed the toxicity of H to microorganisms. The studies addressed inactivation as well as mechanisms of action and mutagenicity but provided little data on actual toxic concentrations. Bacteria, phages, viruses, and yeasts were inactivated at similar concentrations, which were lower than concentrations that inactivated some enzyme systems. As noted previously, the toxicity of H to microorganisms probably precludes biodegradation. 

Table I shows the retention of E coh and MS2 by 1 and 2 layers of the PAC media. Fifteen ml aliquots of concentrated bacteria and MS2 viras were passed through 25 mm diameter test samples at 40 ml/min. A single layer of the PAC media was capable of retaining >6 LRV of E. coli and approximately 3 LRV of...

IPBC s spectrum of effectiveness comprises also yeasts, e.g. Candida albicans, Saccharomyces cerevisiae, and in considerably higher concentrations bacteria, too. Therefore its use as a preservative for cosmetic and personal care products has become an additional application field. To achieve cost-efficient and effective preservation it is worth combining the microbicide with established cosmetic preservatives (see Part I-Chapter 5.9.). IPBC is listed in the EEC Cosmetics Directive maximum permissible concentration 0.05%. Excluded is the use of the product as an agent for oral hygiene or lip care products. If in leave-on cosmetics (retention on the skin) the IPBC concentration exceeds 0.02%, the note contains iodine must be added. 

Biofilters Dispersion of particles Ash concentration Bacteria death due to acidification and asphyxiation followed by absence of organic matter removal White et al. 1980... 

The effects of pollution can be direct, such as toxic emissions providing a fatal dose of toxicant to fish, animal life, and even human beings. The effects also can be indirect. Toxic materials which are nonbiodegradable, such as waste from the manufacture of insecticides and pesticides, if released to the environment, are absorbed by bacteria and enter the food chain. These compounds can remain in the environment for long periods of time, slowly being concentrated at each stage in the food chain until ultimately they prove fatal, generally to predators at the top of the food chain such as fish or birds. 

Although thiosulfate is one of the few reducing titrants not readily oxidized by contact with air, it is subject to a slow decomposition to bisulfite and elemental sulfur. When used over a period of several weeks, a solution of thiosulfate should be restandardized periodically. Several forms of bacteria are able to metabolize thiosulfate, which also can lead to a change in its concentration. This problem can be minimized by adding a preservative such as Hgl2 to the solution. 

By changing the enzyme and mediator, the amperometric sensor in Figure 11.39 is easily extended to the analysis of other substrates. Other bioselective materials may be incorporated into amperometric sensors. For example, a CO2 sensor has been developed using an amperometric O2 sensor with a two-layer membrane, one of which contains an immobilized preparation of autotrophic bacteria. As CO2 diffuses through the membranes, it is converted to O2 by the bacteria, increasing the concentration of O2 at the Pt cathode. 

Water Groundwater can be treated in anaerobic bioreactors that encourage the growth of sulfate reducing bacteria, where the metals are reduced to insoluble sulfides, and concentrated in the sludge. For example, such a system is in use to decontaminate a zinc smelter site in the Netherlands (95). 

Sulfur Dioxide and Sulfites. Sulfur dioxide [7446-09-5], SO2, sodium bisulfite [15181-46-1], NaHSO, and sodium metabisulfite [23134-05-6] ate effective against molds, bacteria, and certain strains of yeast. The wine industry represents the largest user of sulfites, because the compounds do not affect the yeast needed for fermentation. Other appHcations include dehydrated fmits and vegetables, fmit juices, symps and concentrates, and fresh shrimp (79). Sulfites ate destmctive to thiamin, and cannot be used in foods, such as certain baked goods, that ate important sources of this vitamin. 

Lactic acid-producing bacteria associated with fermented dairy products have been found to produce antibiotic-like compounds caUed bacteriocins. Concentrations of these natural antibiotics can be added to refrigerated foods in the form of an extract of the fermentation process to help prevent microbial spoilage. Other natural antibiotics are produced by Penicillium wqueforti the mold associated with Roquefort and blue cheese, and by Propionibacterium sp., which produce propionic acid and are associated with Swiss-type cheeses (3). 

The nutrient sparing effect of antibiotics may result from reduction or elimination of bacteria competing for consumed and available nutrients. It is also recognized that certain bacteria synthesize vitamins (qv), amino acids (qv), or proteins that may be utilized by the host animal. Support of this mode of action is found in the observed nutritional interactions with subtherapeutic use of antibiotics in animal feeds. Protein concentration and digestibiHty, and amino acid composition of consumed proteins may all influence the magnitude of response to feeding antibiotics. Positive effects appear to be largest... 

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