Fermentation is defined as the conversion of organic substances into products of economic value in an aerobic and anaerobic environment with the help of microorganisms such as fungi, bacteria, yeast, etc.

Eg:- Microorganisms such as bacteria and fungi, yeast are generally used for the production of beer, wine, vaccines, probiotics, bread, kimchi, & fermentation process, etc.


You can also say that fermentation is an operation used for the cultivation of microorganisms or other organic substances into important and significant pharmaceuticals or APIs such as therapeutic, antibiotics, enzymes, proteins and insulin.

Two Main Stages involved in Fermentation

Generally, there are 2 stages in bioprocessing for converting raw material / untreated product (either biological or non-biological origin) to final product:- 

1. Upstream processing

Generally, this step contains three processes i.e., biomass production, biosynthesis of metabolites and bioconversion. Upstream processing includes particulates separation, air purification, chemical hydrolysis, liquid medium preparation, and all other preliminary operations.

Upstream Processing is related with all components and procedures leading to and including the fermentation.

Contain three main areas:-

 1. The cultured microorganism 

  • This involves the procedure for selecting a suitable microorganism 
  • strain improvement to enhance the yield & productivity 
  • maintenance of strain sterility
  • preparation of suitable inoculum

 2. The fermentation medium 

 3. The fermentation process


2. Downstream processing

Final product that is produced or processed in the bioreactor/fermenter must be further operated in the downstream stage to transform it into a beneficial product. Processes or operations that take place in downstream processing include the process of physical separation which contains adsorption, liquid-liquid extraction, solid liquid separation, distillation, drying, etc.  

Downstream Processing involves all the procedures that follow fermentation.

They include:-

  • Harvesting of cells
  • Disruption of cells 
  • Purification of products from cell extracts or the growth medium 
  • Disposal of the effluent wastes

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