Substrate uptake

In these equations, [L = specific growth rate coefficient, v = specific rate of substrate uptake, t = time, x = biomass concentration, Sj = intracellular substrate, and Cj = concentration of intracellular substrate. Several examples where these equations can be applied include nitrogen hmitations in M. citrifolia cultures and phosphate hmited growth in C. roseus, N. tahacum, a.nd Papaver. somniferum. 

Ideally, we would wish for high substrate uptake in the absence of growth and in the absence of maintenance energy requirements. Since aerobic micro-organisms control their rates of substrate uptake when growth is slow or absent, manipulation of substrate uptake may be necessary. 

K+ has a role in substrate uptake and during effident exopolysaccharide synthesis, adequate supplies of this ion is essential for ensuring suffident intracellular carbon substrate is maintained. Other ions, such as phosphate and magnesium, have roles in the acylation of exopolysaccharides and influence their physical properties. 

Bubble size distribution Growth stimulants Specific substrate uptake rate... 

Media flow rate, ml/h Retention time, t, h Cell Density, gd Substrate concentration (S), gd 1/5, 1/g - rA, Rate of substrate uptake, g/l.h l/-rA Ethanol concentration, gd... 

As mentioned above, pH directly influences substrate uptake rates of PAOs and GAOs. Filipe et al. (2001a) suggested that the ratio of phosphate release to acetate uptake by PAOs is directly influenced by pH with following the relationship [3]. 

Schut F, M Jansen, TMP Gomes, JC Gottschal, W Harder, RA Prins (1995) Substrate uptake and utilization by amarine ultramicrobacterium. Microbiology (UK) 141 351-361. 

Equation 7.40 suggests that the specific growth rate (p) can be obtained as the slope in a plot of /nXv(t,) + jDdt versus t,. Equation 7.41 suggests that the specific substrate uptake rate (qs) can also be obtained as the negative slope in a... 

The determination of the COD components depends on the fact that the substrate uptake can be experimentally related to the OUR curve. The heterotrophic yield constant, YHw, that is experimentally determined from procedure number 1, Section 7.2.1, relates the oxygen uptake to the readily biodegradable substrate that is consumed irrespective of its origin, being either directly available or continuously produced from hydrolyzable COD fractions. 

Figure 3. Schematic view of the substrate uptake rate versus concentration relationship as described by the whole-cell Michaelis-Menten kinetics. Q is the substrate uptake rate, <2max the biologically determined maximum uptake rate per biomass, c the substrate concentration, and Kj the whole-cell Michaelis constant, i.e. the concentration resulting in 2max/2 (mass of substrate per volume). At c

Model calculations have demonstrated that active cells are surrounded by zones containing substrate concentrations lower than those of the bulk liquid [12-14], This concentration gradient results from the dynamic interplay between the rates of substrate uptake and diffusion through the diffusion layer surrounding the cell (see [15] for details). Boone et al. [13] developed a model using spherical coordinates that allows calculation of the diffusive substrate flux to a suspended spherical cell. In their model calculations, the cell surface concentration was set to arbitrary values between zero and about half of the bulk concentration. It... 

Figure 4. Calculation of the substrate uptake driven diffusive transfer of the polycyclic aromatic hydrocarbon anthracene to Mycobacterium sp. LB501T (solid line) and three other imaginary bacterial strains differing from strain LB501T by their 100-fold lower (dots), 10-fold lower (long dashes) and 10-fold higher (short dashes) specific affinities,...

Tune, B.M., Sibley, R.K. and Hsu, C.Y. (1988). The mitochondrial respiratory toxicity of cephalosporin antibiotics. An inhibitory effect on substrate uptake. J. Pharmacol. Exp. Ther. 245 1054-1059. 

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