Growth and Production

Semifermentation Process. In this process, the metaboHc intermediate in the amino acid biosynthesis or the precursor thereof is added to the medium, which contains carbon and nitrogen sources, and other nutrients required for growth and production, and the metaboHte is converted to the... 

As you might have already gathered, the majority of industrial fermentations are batch processes. In closed batch systems, the growth medium is inoculated with cells and growth and product formation is allowed to proceed until the required amount of conversion has taken place. After harvesting the culture the vessel is cleaned, sterilised and filled with fresh medium prior to inoculation. For some processes, addition of all the feedstock prior to inoculation, as is done in closed batch fermentations, is undesirable and it is preferable to incrementally add the carbon source as the fermentation proceeds. Such a process is known as fed-batch culture and the approach is often used to extend the lifetime of batch cultures and thus product yields fed-batch cultures are considered further in Section 2.7.4. 

Continuous culture is not considered suitable for citric add production the requirement for a multi-tank system to separate growth and product formation would make the process uneconomic. 

Before we leave this description of the production of penicillin, we should point out that it is not essential that growth and production phases are physically separated. It is possible by using a pre-set feed pattern to carry out both processes in the same vessel. 

These criteria have been found to give comparable growth and product rates compared with the pilot-scale operation. If we need to control maximum shear, the value of NDj should be the same in both the pilot- and large-scale vessels. 

PET is the maximum ET that can result from a set of climatic conditions. It is limited by the amount of energy available to evaporate water. The equivalent term reference crop evaporation is used by research workers who investigate the physics of ET. For the purposes of plant growth and production, PET is defined as the amount of water that would return to the atmosphere if abundant, freely transpiring plant leaves are available, and the water supply to the plants is abundant and unrestricted. The magnitude of PET is useful for preliminary planning to identify the maximum possible performance that might be expected from an ET cover. 

The continuous regime of poly(3HB) production has some important advantages. High and constant productivities are obtainable because high rates of growth and product formation can be maintained over long periods. Continuous cultivation methods are also convenient for the use of toxic substrates, and constant product quality should be easily obtained. 

Fig. 3.9 The positive effect of nitrogen fertilizer (potassium nitrate) on the growth and productivity of transgenic sprouts (A.) The growth rate, measured as the increase in fresh weight during sprouting.

Chang YC, Chou CC (2002) Growth and production of cholesterol oxidase by alginate-immobilized cells of Rhodococcus equi No 23. Biotechnol Appl Biochem 35 69-74... 

Exact nutrient requirements of producer cell line to maximize cell growth and product production. 

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