1. CONTINUOUS CULTURE

2. INDEX :- INTRODUCTION DEFINATION SPECIAL CASES ADVANTAGES
DISADVANTAGES

3. Continuous culture :-
The exponential growth in batch culture can be prolonged by the addition of more substrate but it will lead to the overflowing from culture vessel .
Hence , a overflowing device is fitted to the fermentor such that the added medium displace an equal volume of culture from vessel than continuous production of cells can be taken place & thus system called CONTINUOUS CULTURE .

4. If the medium is fed continuously to batch culture at a suitable rate , then a steady state is achieved that formation of new biomass by the culture is balanced by the loss of cell from the vessel .
The flow of media in the vessel is related to volume of vessel in the form of dilution factor .
D = F/V where
F= flow rate
V= volume of vessel
D= dilution factor

5. Change in cell biomass concertration :-
Change in cell biomass= Growth – Output
dx/dt = µx – Dx
Under steady state , the cell concertration remains constant that is dx/dt = 0 , so
µx = Dx
cut x both side
µ = D
Under steady state the specific growth rate is controlled by dilution rate .

6. Special case :- if D > µ
The cell washout rate will be higher than the cell being produced .
The slowly cell will grow at a higher growth rate due to the availability of the substrate to the fewer cell present inside the vessel .
Ultimately the growth rate will be equal to the value dictated by dilution rate and biomass concertration will increase .
The steady state will be re-established .

7. Advantages :-
Cells can be maintained at a constant physiological state because the specific growth rate and the substrate concertration can be set simply by setting the dilution rate [ µ=D ] .
It can take advantage of cell immobilization which allows the maintenance of high concertrations of cells in the reactor at low substrate concertrations.

8. Most downstream processing operations operate in a continuous manner .
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 .

9. Disadvantages :-
These 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 .
They are unsuitable for producing various fermented foods and beverges which depend on a complete batch cycle to produce full flavours .
Large scale continuous cultures are still regarded as risky ventures .

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