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Environment nutrients, supply

Suspension systems can be operated in different modes batch, fed-batch, chemostat, and perfusion (Fig. 1). These operation modes differ basically in the way nutrient supply and metabolite removal are accomplished, which in turn determines cell concentration, product titer and volumetric productivity that can be achieved [8]. The intrinsic limitation of batch processes, where cells are exposed to a constantly changing environment, limits full expression of growth and metabolic potentials. This aspect is partially overcome in fed-batch cultures, where a special feeding strategy prolonges the culture and allows an increase in cell concentration to be achieved. In perfusion and chemostat processes nutrients are continuously fed to the bioreactor, while the same amount of spent medium is withdrawn. However, in perfusion cultures the cells are retained within the bioreactor, as opposed to continuous-flow culture (chemostat), which washes cells out with the withdrawn medium [9]. [Pg.131]

Nahapetian AT, Thomas JN, Thilly WG (1986), Optimization of environment for high density VERO cell culture effect of dissolved oxygen and nutrient supply on cell growth and changes in metabolites, J. Cell Sci. 81 65-103. [Pg.457]

The fungal remains in the deep karst environment of Warstein exhibit some similarities with the Black Forest occurrences. Ffowever, the nutrient supply in the karst environment was much better than it was in the very deep fractures of the Black Forest granites. [Pg.396]

The stability of minerals has long been of interest to soil scientists. One of the major processes occurring during the development of soils is the formation of secondary minerals from primary minerals. Plant nutrition in natural environments is dependent on mineral nutrients supplied by mineral weathering. Soil acidification, whether it results from natural processes of soil development or is accelerated by anthropic acidic deposition, is mediated by weathering processes. [Pg.151]

On a localized basis, human activity can affect the carbon cycle indirectly by increasing the supply of mineral nutrients to aquatic environments. A large nutrient supply supports high levels of primary productivity by phytoplankton (algae and cyanobacteria), a process described as eutrophication. Under natural conditions, eutrophication is usually seasonal outside the tropics, being related to the stratification of the water column and the succession of phytoplankton (see Section 3.2.4). When nutrients are exhausted in the upper... [Pg.292]

The environment must supply the appropriate nutrients and provide the aerobic or anaerobic conditions required. [Pg.1567]

The final phase. Phase IV, is the death phase where a decrease in live cell concentration occurs. This decline is a result of the toxic by-products, harsh environments, and/or depletion of nutrient supply. [Pg.423]

Water has been applied to several arctic ecosystem types to simulate increased precipitation, with the expectation that the additions would enhance plant production. The production could be stimulated either directly as a response to decreased drought, most likely to occur in dry polar deserts or semideserts (Aleksandrova, 1988 Bliss et ai, 1984), or indirectly by enhancement of nutrient supply to plants. For instance, increase in soil moisture focilitates the transport of nutrients toward the plants roots (Chapin ct al, 1988) and creates favorable environments for N fixation (Gold and Bliss, 1995). [Pg.145]

Because productivity in most arctic ecosystems is constrained by low nutrient availability, the most common responses to nutrient addition are increases in nutrient uptake and plant nutrient mass followed by increased plant production and biomass. Similar effects on growth can be expected in response to warming through direct responses of increased productivity in a wanner environment and through enhanced nutrient uptake as a result of increased nutrient supply rate, as mineralization is likely to increase in the warmed soils (Nadelhoffer et al, 1992). [Pg.145]

Nutrient release into the environment is rapid in nutrient-rich wetlands (eutrophic wetlands) where nutrient supply meets the needs of microbial growth. Nitrogen and phosphorus release is directly related to the decomposition end products methane and carbon dioxide (Figure 5.65). In contrast, nutrients may be held tightly within the microbial biomass component of low-nutrient wetlands. [Pg.177]

Autotrophic BU are more dependent upon their physicochemical environments to supply essential elements than are heterotrophs, but, of course, autotrophs are less dependent upon nutrient uptake to supply their energy needs. Herbivores can usually obtain most of their nutrient requirements from the plants they eat, although nutritional requirements of plants and animals differ somewhat, and this may lead to nutritional deficiencies in the animals. [Pg.295]


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Nutrient supply

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