Fermentation System

Types

There are 3 types of fermentation system: Batch, Fed-batch and Continuous

 Batch Fermentation

The operation

  1. Medium contain substrate and nutrients were add at time = 0
  2. Medium is sterilized and cooled
  3. Then add the microorganism
  4. After that, add chemical agents to control pH, foam formation and contaminated bacteria.
  5. The result show minimal change in net volume of medium

Advantages

  1. Easier set-up and operation
  2. Less complication in process control
  3. Less susceptibility to microbial contamination
  4. High yield

Disadvantages

Low productivity because take long time for:

  1. Cleaning fermenters
  2. Prepare of fermenters
  3. The initial lag phase during growth of the desired medium
  4. The operation run until complete and no product be taken out during fermentation

 

Fed-Batch fermentation

  1. Same as batch fermentation
  2. But the concentrated medium is added into fermenter until desired volume is reached.
  3. Volume inside the fermenters is changes
  4. Advantages and disadvantages same with batch fermentation
  5. The operation run until complete and no product be taken out during fermentation

 

Continuous fermentation

  1. Low substrate concentration + high biomass concentration
  2. Involve 2 stages: Start-up & Steady state

Operation

  1. Start-up stages, same with batch mode until cell grow to the desired cell concentration
  2. Cell grow until active culture established
  3. Substrates and nutrients continuously fed into fermenter and at the same time, product is removed
  4. Volume at fermenter keep constant at steady state operation
  5. Cell can be suspended or immobilized in the fermenter

Recycle system

Membrane module: Separate cell in the product and recycle back in fermenter to keep its cell mass concentration high

How to ensure consistent performance?

  1. Feed rate should be properly controlled population
  2. Microorganism population should be maintained
  3. Avoided contamination

Advantages

High Productivity

Disadvantages

  1. Contamination
  2. Wash out of cell from bioreactor at high flow rate
  3. Final product yield lower than batch fermentation
  4. Higher cost

 

Example of fermentation system

Reference: Book: Nurhan Turgut, “Food and Industrial Bioproducts and Bioprocessing”, Wiley-Blackwell 2012

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