Growth limiting

This is an old, familiar analysis that applies to any continuous culture with a single growth-limiting nutrient that meets the assumptions of perfect mixing and constant volume. The fundamental mass balance equations are used with the Monod equation, which has no time dependency and should be apphed with caution to transient states where there may be a time lag as [L responds to changing S. At steady state, the rates of change become zero, and [L = D. Substituting ... 

The multi-stream multi-stage system is a valuable means for obtaining steady-state growth when, in a simple chemostat, the steady-state is unstable eg when the growth-limiting substrate is also a growth inhibitor. This system can also be used to achieve stable conditions with maximum growth rate, an achievement that is impossible in a simple chemostat (substrate-limited continuous culture). 

Biomass feedback refers to increasing the concentration of biomass in the culture vessel. This is achieved by fitting some device, either internally or externally, to the continuous culture which retains or returns biomass to the vessel. The main advantage of biomass feedback is that the maximum output rate of biomass (and products) in the vessel with a given medium can be increased. This is particularly useful when the growth-limiting substrate is unavoidably dilute, for example if substrate has low solubility or has to be limited because of the formation of an inhibitory product. 

Aim3 aerobic bioprocess was operated in a continuous mode with nitrogen as the growth limiting nutrient. The steady state biomass concentration (x), the biomass yield coefficient (Yx/S) and the product yield coefficient (Yp/t) were determined at a low and at a high dilution rate (D). 

Explain why it would be inadvisable to use the carbon source as growth limiting nutrient in the sucdnoglycan fermentation. 

It has been suggested that fungi grow in filamentous form at an exponential rate with a constant specific growth rate (ji) until some substrate becomes growth limiting, according to the Monod equation 4 6... 

The possible effects of increased atmospheric CO2 on photosynthesis are reviewed by Goud-riaan and Ajtay (1979) and Rosenberg (1981). Increasing CO2 in a controlled environment (i.e., greenhouse) increases the assimilation rate of some plants, however, the anthropogenic fertilization of the atmosphere with CO2 is probably unable to induce much of this effect since most plants in natural ecosystems are growth limited by other environmental factors, notably light, temperature, water, and nutrients. 

It is possible for two or more substrates to become simultaneously limiting. Define a growth limitation factor, G, < 1, for substrate i such that... 

Stress is a broad term often used with animal cells. Frequently mechanical forces are meant using this term but chemical stress is also important cultivating animal cells. The chemical environment of the cell in a reactor have to be considered very carefully. The complexity of the medium requirements and the metabolic pathway cause very often growth limitations. Studying these limitations in order to find the reasons showed to be difficulty because of the complexity of the system. Nevertheless, glucose, glutamine, lactate and ammonia are found to be critical parameter as well as the osmotic pressure. 

A log normal distribution will give a straight line when plotted on this ti pe of paper. This means that the PSD is not limited, i.e.- aU sizes of particles are present from - to +°°. However, if the PSD is growth-limited, it will readily apparent from the graph. Ostwald ripening, a mechanism where large... 

Mars AE, J Houwing, J Dfolfing, DB Janssen (1996) Degradation of toluene and trichloroethylene by Burk-holderia cepacia G4 in growth-limited fed-batch culture. Appl Environ Microbiol 62 886-891. 

M. van Noordwijk and S. C. van de Geijn, Root, shoot and soil parameters required for proeess-oriented models of crop growth limited by water or nutrients. Plant Soil I8S (1996). 

Edgar The endoreplication cycles might be a better example of growth-limited cycles. Christian Lehner has done experiments in which cyclin E is overexpressed in endoreduplicating cells. They get stuck in Gl. We have then expressed Myc in these Gl-arrested cells it doesn t make them grow much. They absolutely require endoreplication for growth. 

If nitrogen (in the form of ammonia) is growth limiting, the potential applications of acetyl-CoA and NAD(P)H are restricted. Liberated NAD(P)H cannot be consumed for reductive syntheses, for instance of amino acids, it remains available and starts to inhibit citrate synthase [45, 46]. To the extent that the TCA cycle is thereby inhibited, acetyl-CoA should become available for the 3-ketothiolase, and could flow into poly(3HB) (Fig. 1, Table 1). 

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