Downstream processing involves treating culture broth post-fermentation to concentrate and purify products, which includes cell disruption, separation, and purification methods. Techniques such as centrifugation, filtration, and various chromatography forms are employed to recover and refine products. Final processing steps, known as product polishing, ensure the product is stable and transportable through methods like crystallization and drying.

1. Downstream Processing

2. Downstream processing, what and why
Downstream processing is any treatment
of culture broth after fermentation to
concentrate and purify products.
2

3. Downstream Processing
Crude product
Product recovery
Purify the product
Removal of insoluble
Finished
product
Cell disruption
Market

4. Cell disruption
• Some product are intracellular including many
enzymes and proteins required to disrupt the cell
and release these products e.g. Yeast
• Cell disruption can be achieved by both
mechanical and non-mechanical methods.
• Mechanical- sonication and liquid shear
homogenization etc
• Non mechanical- autolysis, osmosis shock etc.

5. Removal of insoluble's
Separation of cells, cell debris or other
particulate matter from fermentation broth
culture.

6. Filtration
Separation of particles from liquid by applying
a pressure to the solution to force the solution through
a filter. Filters are materials with pores.
Particles larger than the pore size of the
filter are retained by the filter.
Particles smaller than the pore size of the filter pass
through the filter along with the liquid.

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Membrane Fraction Technologies
Reverse Osmosis
(<200 MW)
Ultrafiltration
(2000 - 50,000 MW)
Nanofiltration
(200 - 700 MW)
Micro filtration
(100,000 MW)

8. Centrifugation
 Centrifugation used to separate particles as
small as 0.1μm diameter and is also suitable
for some liquid-liquid separations.
 Higher speed centrifuge are required for the
separation of the smaller particles
 Use of the centrifugal force for the separation
of mixtures

9. Disc stack centrifuge

10. Coagulation and Flocculation
Coagulation:
Forming semisolid lumps in a liquid.
Flocculation:
Forming woolly cloudlike aggregations.

11. Product purification
• Removing components with properties similar
to those of the products
Chromatography
• Separates molecules by their chemical and
physical differences
E.g. – adsorption chromatography
•
affinity chromatography
•
ion exchange chromatography etc.

12. Gel Filtration Chromatography

13. dialysis
• These membrane separation techniques are
primarily used for the removal of low molecular
weight solutes and inorganic ions from a
solution
Distillation
• Separating components with different
volatilities. Such as organic solvents , beer, wine
and sprits.

14. Product Polishing
 Final processing steps which end with
packaging of the product in a form that is
stable and easily transportable
 Crystallization, concentration and drying
are typical unit operations

15. Crystallization Process
Liquid
Mixture
Generation of
Supersaturation
:Driving force
Final Product
Nucleation:
Birth of
Solid Phase
Crystal Growth

16. Crystallization
- by cooling saturated solution

17. Drying
Drying involves the transfer of heat to the
wet material and removal of the moisture as
water vapor.
Drying Methods
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Atmospheric drying
Vacuum drying (Decompression )
Freeze-drying (lyophilization)
Spray drying

18. lyophilization
Freezing the material
Reducing the surrounding pressure and
adding enough heat to allow the frozen
water in the material to sublime directly
from the solid phase to gas.

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