Anaerobic kinetics

Hulley, M.E., Toogood, H.S., Fryszkowska, A., Mansell, D., Stephens, G.M., Gardiner, J.M., and Scmtton, N.S. (2010) Focused directed evolution of pentaerythritol tetranitrate reductase by using automated anaerobic kinetic screening of site-saturated libraries. ChemBioChem, 11, 2433-2447. 

Focused directed evolution of pentaerythritol tetranitrate reductase by using automated anaerobic kinetic screening of site-saturated libraries. ChemBioChem, 11, 2433-2447. 

Sludge is destroyed by microorganisms and the kinetics of their life processes is temperature dependent. Short anaerobic digestion detention times are obtained at 35°C. Even shorter detention times are possible at 52—54°C, but detention in this range is costly. An increase in detention time occurs at 35—43°C and then a progressive decrease takes place until 52—54°C. This variation is caused by a change in character of the dominant process organisms. 

An anaerobic digester is a no-recycle complete mix reactor. Thus, its performance is independent of organic loading but is controlled by hydraulic retention time (HRT). Based on kinetic theoiy and values of the pseudo constants for methane bac teria, a minimum HRT of 3 to 4 days is required. To provide a safety factor and compensate for load variation as indicated earlier, HRT is kept in the range 10 to 30 days. Thickening of feed sludge is used to reduce the tank volume required... 

This is a simplified treatment but it serves to illustrate the electrochemical nature of rusting and the essential parts played by moisture and oxygen. The kinetics of the process are influenced by a number of factors, which will be discussed later. Although the presence of oxygen is usually essential, severe corrosion may occur under anaerobic conditions in the presence of sulphate-reducing bacteria Desulphovibrio desulphuricans) which are present in soils and water. The anodic reaction is the same, i.e. the formation of ferrous ions. The cathodic reaction is complex but it results in the reduction of inorganic sulphates to sulphides and the eventual formation of rust and ferrous sulphide (FeS). 

Emerson, S. and Widmer, G. (1978). Early diagenesis in anaerobic lake sediments II. Equilibrium and kinetic factors controlling the formation of iron phosphate. Geochim. Cosmochim. Acta 42,1307-1316. 

For an anaerobic aqueous sulphuric acid medium the kinetics are ... 

Quite different kinetics are exhibited by the anaerobic oxidation of alkyl-benzenes by cobaltic acetate in a 95 % acetic acid medium , viz. 

The initial step of the anaerobic ferrocyanide reduction of cumene hydroperoxide to acetophenone has kinetics ... 

A few details have been reported on the slow reductions of 8303 by As(ni) and T1(I) . In the anaerobic reductions by As(III) the reaction is first-order in 820 and although As(III) certainly catalyses decomposition, the dependence of the rate on [As(III)] is small. Aeration leaves the rate of spontaneous decomposition of 820g unaffected, but the As(III)-catalysed route is accelerated by a factor of ten, the kinetic law remaining unchanged. The oxygen effect is interpreted in terms of the chain reaction... 

Peijnenburg WJGM, KGM de Beer, HA den Hollander, MHL Stegeman, H Verboom (1993) Kinetics, products, mechanisms and QSARs for the hydrolytic transformation of aromatic nitriles in anaerobic sediment slurries. Environ Toxicol Chem 12 1149-1161. 

The degradation of Cg-benzene was studied in anaerobic enrichment cultures when phenol, benzoate, and toluene were detected, and the kinetics of their formation studied (Ulrich et al. 2005). 

The partial dechlorination of chlorinated anilines has been examined in anaerobic slurries, which has already been noted (Kuhn et al. 1990), while D. hafniense (frappieri) strain PCP-1 is able to dechlorinate a wide range of polychlorinated aromatic substrates including phenols, catechols, anilines, pentachloronitrobenzene, and pentachloropyridine (Dennie et al. 1998). Both pentachloro-aniline and 2,3,5,6-tetrachloroaniline were partially dechlorinated to dichloroanilines, although the orientation of the substituents was unresoved. The kinetics of dechlorination of pentachloroaniline have been described (Tas et al. 2006). 

Rossetti S, LL Blackall, M Majone, P Hugenholtz, JJ Plumb, V Tandoi (2003) Kinetic and phylogenetic characterization of an anaerobic dechlorinating microbial community. Microbiology (UK) 149 459-469. 

Shen H, GW Sewell (2005) Reductive biotransformation of tetrachloroethene to ethene during anaerobic degradation of toluene experimental evidence and kinetics. Environ Sci Technol 39 9286-9294. 

These should be constructed from material collected from the relevant site and simulate aerobic, microaerophilic, or anaerobic conditions. They should provide the kinetic data necessary for large-scale operation, and specifically address the following—although some of them will already have been examined ... 

Scheme 10.7 Oxidative kinetic resolution of alcohols using chiral bis-NHC hgands [26-28] 10.3.1.2 Anaerobic Oxidation...

Fig. 26. Photolysis kinetics of nitroxylmethylcobinamide. The solution was photolyzed anaerobically in the spectrometer cavity. Disappearance of the signal was monitored by following the decrease in maximum intensity of high field line as a function of time...

A steady-state kinetics study for Hod was pursued to establish the substrate binding pattern and product release, using lH-3-hydroxy-4-oxoquinoline as aromatic substrate. The reaction proceeds via a ternary complex, by an ordered-bi-bi-mechanism, in which the first to bind is the aromatic substrate then the 02 molecule, and the first to leave the enzyme-product complex is CO [359], Another related finding concerns that substrate anaerobically bound to the enzyme Qdo can easily be washed off by ultra-filtration [360] and so, the formation of a covalent acyl-enzyme intermediate seems unlikely in the... 

Looking back at Table 4.4 the anaerobic cyclic steady state is from the first product of C0(C02) reduction, formaldehyde (HCHO), to [CH2OH] . This step requires a kinetic pathway in redox potential from -0.2 to -0.6 V versus the H2/H+ potential at pH 7, where sulfur is the oxidised waste ... 

Boija, R., and Banks, C. J., Kinetics of an Anaerobic Fluidized Bed System Used for the Purification of Fruit Processing Waste-Water, Chem. Eng. J., 54 B25 (1994)... 

Nevertheless, a rapid disappearance of resistant bacteria was observed after stopping the antibiotic treatment (fig. 5). Different kinetics of disappearance were, however, observed. The aerobic species showed a more rapid return to the baseline sensitive status whereas the anaerobic bacteria, especially the Gram-negative rods, regained sensitivity to rifaximin more slowly. In any case, 3 months after the end of treatment resistant strains were no longer detectable in the feces [82], These results support the cyclic use of rifaximin that has been adopted by the investigators in the treatment of hepatic encephalopathy [77] and colonic diverticular disease [79]. 

Sponza DT, Isk M (2004) Decolorization and inhibition kinetic of Direct Black 38 azo dye with granulated anaerobic sludge. Microbial Technol 34 147-154... 

The assessment of reaction kinetics by means of batch tests may be strongly affected by dye adsorption on the biophase and supports. The relevance of the adsorption phenomena of dyes on biophase has been addressed in studies regarding free cells [41], granular support biofilm [24], entrapped cells [11, 18], anaerobic sludge [10,24,31,34] and biological activated carbon (BAC) [42,45,47,48]. They have pointed out that the kinetics may be overestimated if the assessment of the adsorption contribution to the dye removal is not taken into account. Under batch conditions, the dye is fastly split between the liquid phase and the biophase, resulting in a sharp reduction of the dye concentration in the liquid phase until adsorption equilibrium is approached. The rate of dye adsorption must be estimated and ruled out in the kinetic assessment. 

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