Nutrient supply

Fig. 8. Steady-state model for the earth s surface geochemical system. The kiteraction of water with rocks ki the presence of photosynthesized organic matter contkiuously produces reactive material of high surface area. This process provides nutrient supply to the biosphere and, along with biota, forms the array of small particles (sods). Weatheriag imparts solutes to the water, and erosion brings particles kito surface waters and oceans.

Culture with continuous nutrient supply can be operated in two modes (i) variable volume (ii) fixed volume. 

In fact, significant substrate concentration gradients may exist for cells immobilised in biofilm. Cells located close to the nutrient supply are likely to maintain higher quality and activity compared with cells located relatively further away, leading to differentiation in the quality or activity of the immobilised cell population. This differentiation is more pronounced if there are starvation regions. In practice, zero substrate concentration may exist inside the biofilm, because in these regions the cell physiology may be markedly different from that of the freely suspended cells. 

Vaupel P, Kallinowski F, Okunieff P (1989) Blood flow, oxygen and nutrient supply, and metabolic microenvironment of human tumors a review. Cancer Res 49 6449-6465... 

Scale-up to the industrial scale is only achievable and economical reasonable in stirred or airlift systems. To achieve high cell densities optimal nutrient supply is necessary. Therefore transport limitations have to be avoided by good mixing of cells (microcarrier) and medium. This movement caused by stirrer or aeration leads to mechanical forces evoking severe cell damage or cell death [3,4]. 

Hollow fiber reactors [7] and dialysis reactors [8] avoid shear stress by separating cells and flowing media. In both reactors nutrient supply takes place by diffusion through the capillary wall or the dialysis membrane. 

It is clear that the nutrients in soil are important for plant development and that a good nutrient supply within the soil gives healthy plants. However, no profound research results have yet been pubUshed on the most optimal soil conditions. 

M. C. Drew, L. R. Saker, Nutrient supply and the growth of the seminal root system in barley II. Localized compensatory changes in lateral root growth and the rates of nitrate uptake when nitrate is restricted to only one part of the root system. J. E.xp. Bot. 26 79 (1976). 

Regarding the conditions for the biological oxidation, the optimum pH is in the range of 7-9, temperature of about 30°C, nutrients supply and the electric conductivity of the washing liquid must be kept between 30 and lOOmS/cm. In general, neutrophilic sulfide-oxidizing cultures of Thiobacillus species can be used, especially T. denitrificans. 

Although the microbiota are not as essential for nutrient supply to the pig as they are in ruminants, these organisms do provide some benefit to their... 

Oschlies A (2008) Eddies and upper-ocean nutrient supply, pp 115-130. In Hecht and Hasumi... 

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