Oracle Stream Explorer - Simplifying Event/Stream Processing
Down Stream Processing
Transcript of Down Stream Processing
o After the fermentation has been completed, the product is
harvested and recovered. This is called (DSP).
o The fermenter is mainly determined by the DSP operations,
viz., how well the fermented product, and by-products, are
separated from the broth.
o OTA (1984) mentions the interesting case of the humulin
(human insulin) plant built by Elililly and company in which
over 85% of the company staff is employed in the DSP
phase of the plant processes.
o A representative sample of some DSP operations
may include most or all of the operations:
Separation operations
o filtration, centrifugation, flotation, disruption
Concentration operations
o Solubilisation, extraction, thermal processing
membrane filtration, precipitation.
Purification operations
o Crystallization, chromatography
Marketing operations
o Drying, packing, storage
ETHANOL FERMENTATION PROCESSESFEED
Glucose Medium
Lactose Medium or
Whey permeate
PRETRETMENT
Adjust pH
Added Nutrients
STERILIZATION
FEED STORAGE
MEMBRANE
BIOREACTIONS
PRODUCT (Ethanol)
o The sale price of most biotechnology products is
inversely proportional to their concentration leaving the
bioreactor.
o This circumstance has created an incentive to develop
reactor configurations, designs, and conditions that
yield a higher product broth or culture concentration.
o Considerations of this type have particularly influenced
the programmes involving mammalian cell culture.
In this culture, several different mass culturing
technologies are being tried for scale up and
commercialization.
These include free suspension cultures in mixed batch
flow reactors.(i.e.,)these reactors include spinner
flasks, airlift reactors in which the cells are entrapped
in spherical microcapsules.
Free cell suspension cultures require rigorous DSP
processing because they usually attain rather low cell
and product concentration.
In general, greater emphasis has been placed on
genetic engineering and fermentation technology as
compared to downstream processing aspects.
The recovery of microorganisms from fermented broth
presents a fairly difficult solid-liquid separation
process.
Some representative solid phases that may have to be
separated from various fermenters include cells of
bacteria, fungi, algae, plants, animals, and cellular
debris.
The separation process to be applied to these various
forms depends on the concentration and size of the
solids.
Plant and animal cells usually do not withstand the
same extent of applied shearing force as do microbial
cells.
The primary stages of separation are greatly
influenced by broth conditioning, whose major
objective is to aggregate the cells to from larger
clumps or flocs and hence reduce the separation
costs.
Broth conditioning techniques are based on physical,
chemical or biological principles.
Examples of physical techniques include heating,
freezing, mechanical (e.g., homogenizers),
ultrasonic's, and electrical treatments.
Chemical techniques are exemplified by
coagulation(by multivalent metal ions), flocculation (by
organic polymers or polyelectrolyte's), pH change, and
lysis (by surfactants).
Biological techniques of broth conditioning include the
use of enzymes such as proteases, lipases, and
amylases, ageing, lysis (by antibiotics, e.g., penicillin),
antigen-antibody interaction between cells, and genetic
(e.g., incorporation of genes responsible for
flocculation.
o the following operations to facilitate cell separation:
1. sedimentation-used in yeast production and ethanol
production industries.
2. Flotation-Mainly used in alcoholic beverages industry.
3. Filtration and ultra filtration-Filter presses are used in
the older, brewing and distillery industries whereas
rotary vacuum drums are more often employed in the
modem bio-technological processes ,e.g.,
pharmaceutical and food industries.
Ultra filtration(UF)is a pressure-driven membrane
separation process for dissolved and suspended
materials.
o UF can be used for (a) purification of culture medium
prior to bioconversion or fermentation, (b) harvesting
of cells after fermentation, (c) removal of cell debris
after lysis, (d) concentration of product, and (e) making
pyrogen-free water for final product make-up and final
rinsing of vials.
(4) Centrifugation- this is perhaps the most popular DSP
technique, especially in cases involving large cells
fermented on a large scale.
o In general, disc nozzle machines are used for large-
scale production, e.g., of yeast, and are not very
suitable for bacteria.
(5) Cross–flow membrane filtration- This is especially
suitable for the small-scale high-value applications.
o The principle of electro-phoretically assisted cross-
flow filtration technique is illustrated.
The cross-flow technique include applied voltage,
degree of turbulence
The makes membrane processes specially suitable for
the treatment of thermally-or chemically-sensitive
biological.
In any typical microbial production system, there are
four chief areas where membranes may used to
advantages;
These are(1) sterilisation of bioreactor feed
streams(e.g., nutrients, enzyme, oxygen, air, water);(2)
DSP of spent medium;(3) enzyme immobilization; and
(4) on-line monitoring of bioreactor constituents.