Contamination, microbial extent

When proteinoids were heated in buffer at pH 6.2 or 6.8, loss of catalytic activity was observed. The extent of loss ranged from 95 to 11% (Table II). Those proteinoids that initially showed higher levels of activity relative to histidine were the most affected by the heat treatment. After heating, the level of activity was comparable to that of the equivalent amount of histidine, or to that of mineral acid hydrolysates of the polymer. Under similar conditions, a-chymotrypsin was 97% inactivated. The fact that the control tests on L-histidine or A -carbo-benzoxy-L-histidine showed no effect is consistent with the inference that inactivation is due to disruption of a macromolecular conformation. Copolymers prepared from only aspartic acid and histidine were also active on NPA and were inactivated by the heat treatment. The percentages of inactivation ranged from 62 to 19. Polymers prepared and processed under aseptic conditions were both catalytically active and subject to inactivation by heat. These experiments were performed as routine verification that the respective phenomena do not result from the presence, and subsequent denaturation, of contaminating microbial enzymes. 

Decorative eye cosmetic products have been reported to be subject to pathogenic microbial contamination. Regulatory agencies in several countries, therefore, permit the use of mercury-containing preservatives in eye makeups. The infections reported were to a large extent caused by contamination during use, and the introduction of self-sterilising preparations seems warranted. 

Introduction 4 4.1 The extent of microbial contamination Contamination in manufacture... 

Bioremediation also has its limitations. Some chemicals are not amenable to biodegradation, for instance, heavy metals, radionuclides, and some chlorinated compounds. In some cases, the microbial metabolism of the contaminants may produce toxic metabolites. Bioremediation is a scientifically intensive procedure that must be tailored to site-specific conditions, and usually requires treatability studies to be conducted on a small scale before the actual cleanup of a site.13 The treatability procedure is important, as it establishes the extent of degradation and evaluates the potential use of a selected microorganism for bioremediation. A precise estimate on vessel size or area involved, speed of reaction, and economics can therefore be determined at the laboratory stage. 

Acrylonitrile is also readily soluble in water, and current total discharges to water via industrial effluents are low. Water contamination may also occur following a spill or near a chemical site. In water, acrylonitrile has little tendency to adsorb to sediment, but is subject to biodegradation by microorganisms. The rate and extent of degradation depend upon conditions and upon the time for microbial acclimation. Degradation may approach 100% under favorable circumstances, but may be inhibited by high concentrations of acrylonitrile. 

As a result of the highly reduced state of petroleum hydrocarbons, the preferred and most thermodynamically terminal electron acceptor for microbial processes is oxygen. The inverse relationship between the concentrations of BTEX and dissolved oxygen within a plume is indicative of the extent of microbial metabolism of this class of contaminant. Data from various sites indicate that the natural attenuation of BTEX proceeds at higher rates under oxygenated conditions. The biodegradation of... 

Each site and material must be evaluated before implementing a biological solution. The soil is examined in chemical laboratories to assess the type and extent of the contamination. The microbiological laboratory analyzes the presence and activity of the local microbial strains in the contaminated soil. Biologists then specify the type and quantity of natural additives required to produce maximum degradation rates. 

Although such reactions and the consequences with respect to contaminant fate have primarily focused on soluble humic materials (Carter Suffet, 1982 Madhun et al., 1986 Traina et al., 1989 Morra et al., 1990 Puchalski et al., 1992 Engebretson von Wandruszka, 1994), the participation of microbial products in similar reactions is possible. Dohse and Lion (1994) showed that extracellular bacterial polymers enhanced the transport of phenanthrene in sand columns. The mobilization of contaminants might be beneficial to bioremediation if degradation reactions are not inhibited and substrate bioavailability is increased. Conversely, increased contaminant transport may increase the potential for contaminant movement and likewise the extent of environmental contamination. 

Each piece of equipment used to manufacture or pack pharmaceuticals has its own peculiar area where microbial growth may be supported, and knowledge of its weak points may be built up by regular tests for contamination. The type and extent of growth will depend on the source of the contamination, the nutrients available and the environmental conditions, in particular the temperature and pH. 

Most preservatives interact in solution to some extent with many of the commonly used formulation ingredients via a number of weak bonding attractions as well as with any contaminants present. Unstable equilibria may form in which only a small proportion of total preservative present is available to inactivate the relatively small microbial mass the resulting rate of kill may be far lower than might be anticipated from the performance of simple aqueous solutions. However, unavailable preservative may still contribute to the general irritancy of the product. It is commonly believed that where the solute concentrations are very high, and Aw is appreciably reduced, the efficiency of preservatives is often significantly reduced and they may be virtually inactive at very low Aw. The practice of in-... 

Slaughter technology Extent of microbial contamination before slaughtering Type of contaminating matter... 

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