What are the advantages and disadvantages of using continuous culture.?

Answer 1

adv and disadvantages of continuous cultThe advantages include:

• Cells can be maintained at a constant physiological state because the specific growth rate and the substrate concentration can be set simply by setting the dilution rate (µ = D)
• Continuous cultures can take advantage of cell immobilization which allows the maintenance of high concentrations of cells in the reactor at low substrate concentrations
• Most downstream processing operations (apart from chromatography) operate in a continuous manner. Continuous bioreactors thus fit in will with overall operation of a bioprocess plant
• Continuous reactors do not need to be shut down and cleaned as regularly as a batch reactor and thus have a shorter "turn-around" time. This also reduces costs associated with cleaning and filling of the reactor.

The above advantages give continuous bioreactors a greater productivity than batch bioreactors and thus continuous reactors can be smaller (and thus cheaper) to construct and operate

There are number of reasons why continuous cultures are not widely used in industry. These include:

• Continuous cultures are unsuitable for products which are predominantly produced when growth ceases. Such products include many antibiotics, toxins produced during endospore production by Bacillus spp. and Clostridium spp. and monoclonal antibodies.

When growth ceases, the specific growth rate (µ) = 0. Since at steady state the specific growth rate = dilution rate, any dilution rate greater than zero will cause the population to be washed out. (If µ < D the cells will be washed out).

• They are unsuitable for producing various fermented foods and beveridges which depend on a complete batch cycle to produce full flavours. You should remember that unlike a batch culture, a continuous culture maintains the cells at a single physiological state (ie. the specific growth rate is set by the dilution rate :µ = D)

• Contamination or mutation can have a disasterous effect on the operation of a continuous cultures, especially if the contaminant or mutant is able to maintain a lower concentration of the growth limiting substrate than the desired organism.

• The US-FDA at present will not approve the liscencing of pharmaceuticals produced in continuous cultures. This is because pharmaceuticals must be able to be linked to a batch identification. This is not as easy with continuous cultures.

• Large scale continuous cultures are still regarded as risky ventures. Many managers are unwilling to take such risks.