Oxygen limitation

The growth medium for a bioprocess should ideally provide all the requirements of the process organism in such a way that the organism grows rapidly, produces large amount of the desired product, does not degrade the final product, and is able to survive under harsh environmental conditions (such as shear forces, oxygen limitation etc). 

The oxygen limits are those that should be measured before the addition of a chemical oxygen scavenger. 

The oxygen limit given is measured after mechanical deaeration. In addition, it is recommended that a volatile chemical scavenger be used. 

Under conditions of oxygen limitation, strains of Morganella morganii and Providencia rettgeri degraded hexahydro-l,3,5-trinitro-l,3,5-triazine (RDX) after initial reduction to the nitroso compounds (Kitts et al. 1994). 

Under conditions of oxygen limitation in continuous culture, mixed populations of aerobic bacteria and the strictly anaerobic Methanobacterium formicicum and Methanosarcina barkeri could be maintained (Gerritse and Gottschal 1993a). 

Kukor JJ, RH Olsen (1996) Catechol 2,3-dioxygenases functional in oxygen-limited hypoxic environments. Appl Environ Microbiol 62 1728-1740. 

The procedure is particularly suited to the study of anaerobic transformations since there are no problems resulting from problems with oxygen limitation. A good example is provided by the application of C NMR to the intricate relations of fumarate, succinate, propionate, and acetate in a syntrophic organism both in the presence (Houwen et al. 1991), and in the absence of methanogens (Plugge et al. 1993 Stams et al. 1993). 

Oxygen limitation may be a seriously limiting factor especially in deep subsurface sites, and there is evidence that degradation in the solid phase is less effective than in slurries. 

Madsen EL, CL Mann, SE Bilotta (1996a) Oxygen limitations and aging as explanations for the field persistence of naphthalene in coal tar-contaminated surface sediments Environ Toxicol Chem 15 1876-1882. 

Reduce the aeration rate until the reaction becomes oxygen-limited. This can be done interactively. Maintain this and then reduce the catalyst amount by 1/2 (reduce Vm by one-half)- Does the initial rate decrease by 1/2 Is the reaction still oxygen-limited ... 

Run the process oxygen-limited and observe the increase of Cq at the end of the reaction. 

Biological floes and films, which are present in waste treatment systems and in fermentations, are subject to potential oxygen limitation. 

If oxygen limits growth and multiplication of aerobic bacteria, the adaptive value and inductive mechanism of poly(3HB) synthesis are quite similar to those outlined for nitrogen limitation. 2/H/ generated are not oxidized via elec-... 

R. eutropha is actually an autotrophic hydrogen-oxidizing bacterium which can also produce poly(3HB) from C02, H2, and 02 [34]. The critical factor in such autotrophic cultivation processes is to avoid possible gas explosions. Therefore, a recycled gas, closed circuit culture system equipped with several safety features was developed and the oxygen concentration in the substrate gas phase was kept below the lower limit for gas explosions. A bacterial biomass of 91.3 g 1 1 has been achieved and the poly(3HB) content reached up to 67% per cell dry weight under these oxygen-limited conditions [35]. 

Aerobic The growth kinetics was described by an interacting, balanced and unstructured model characterized by phenol inhibition and oxygen limitation according to a double limiting kinetics [60, 62],... 

Given the high dependency of cerebral energy production and neurotransmitter synthesis on glucose and oxygen, limitations in supply of these substrates results in metabolic encephalopathy. 

Vary N and G under non-oxygen-limiting conditions. What is the effect on the reaction rate ... 

This example treats a diffusion-reaction process in a spherical biocatalyst bead. The original problem stems from a model of oxygen diffusion and reaction in clumps of animal cells by Keller (1991), but the modelling method also applies to bioflocs and biofilms, which are subject to potential oxygen limitation. Of course, the modelling procedure can also be applied generally to problems in heterogeneous catalysis. 

The kinetics used here consider carbon-substrate inhibition and oxygen limitation. Thus,... 

Odour will return in treated slurry as a result of post treatment fermentation. The concentration of readily fermentable substrates, measured as BOD5, provide an indicator of this problem. In continuous culture without oxygen limitation the BOD5 can be described by a model derived from the Monod (13) model of microbial growth (14). The supernatant BOD5 (g/1) from treatment at 15 to 45°C, was described by equation 3 and the whole BOD5 by equations 4 and 5(15). 

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