bioprocess lecture 1

7/29/2019 Bioprocess lecture 1

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CHAPTER 1

INTRODUCTION TO BIOPROCESS

A) INTRODUCTION

1) Classical Biotechnology

The use of carefully cultured microorganisms, animal

cells, and plant cells to produce products useful to

humans.

2) Modern Biotechnology

Often associated with the use of generically altered

microorganisms such as E. coli or yeast for the

production of substances like insulin or antibiotics.

3) There are 5 sub-fields of biotechnology


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4) Biotechnology

- Originally, produce organic chemicals byfermentation (e.g. acetone, citric acid)

- Then, antibiotics become the principal productsof biotechnology.

- Example: E. coli is used to produce insulin(recombinant DNA technology)

5) Biological products come from many sources:

- human & animal tissue

- body fluids (e.g. milk)

- plant material (e.g. oils)

- microbial fermentations

- culture of higher eukaryotes

- raw broths from enzyme reactor


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6) Current trend prefers recombinant cells rather than

direct extraction from human and animal sources

- because of contamination, supply consideration and

ethical issue.

B) Characterisation of biomolecules

Biomolecules differ greatly in nature, different

separation principles are required for their recovery

and purification

1)Their relative molecular masses vary fromapproximately 60 to over 2,000,000.

2)Rather unstable and their stability depend ona)pHb)

Temperature

c)Ionic strengthd)Type of solvent usede)Presence of surfactant


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f)Metal ion, etc3)Many biomolecules are sensitive to shear and

hydrophobic.

4)Sometimes present in low concentrations5) Example of biomolecules produced by microbe

Products produced by microbial activity

Amino acids Lipids

Antibacterial agents Nucleotides and precursors

Antifungal agents Organic synthesis intermediates

Antiprotozoal agents Pharmaceutical significant compounds

Carbohydrates Plant growth factors

Dyes and cosmetics Steroids

Enzymes Toxins

Vitamins and coenzymes

Products being addressed by recombinant technology

Human therapeutics

Enzymes

Amino acids


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C) Common Features of Biological Material that

influence their processing

1)Most of the reactions and processing occur inliquid phase

2)Adsorption , chromatography, membrane and solidphase formation are important for bioproduct

recovery

3)Solids are low in density, highly hydrated & softparticles of small diameter (e.g. cells)

4)Macromolecular & cellular constituents have lowdiffusion rates & high viscosity at low

concentration.

5)Many of the biological materials are sensitive tochanges in pH and temperature (easily denatured)

6)Concentration of product is usually low.

7)Usually high purity is required.


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D) Characterisation of Bioprocesses

1)Almost exclusively batch2)Small scale relative to chemical industry3)Multifunctional equipment4)Very flexible and easy to extend5)Equipment sterilisable6)Suited for containment production7)Validated equipment in case of pharmaceutical

production

Classical example: recovery should be easy to

extend, penicillin production increased from 0.4 to 80

mol/m3 in 40 years. (Due to process optimization,

medium and strain selection)


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E) Elements of Bioseparation

1) Bioprocess = Bioreaction + Bioseparation

2) Processing beyond the bioreaction step is termed

downstream processing. (use bioseparation to

differentiate from conventional process in chemical

engineering).

3) Bioseparation: recover the bioproduct in desired

form, concentration, and purity.

What purity is necessary?

acetic acid or alcohol: little purificationindustrial enzymes: moderate purityfood additives: high puritypharmaceuticals: very high purity


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4) Bioseparation costs a substantial fraction of the

total cost of the final product (40-80%)

5) Bioseparation involved 5 steps:

- Pretreatment- Removal of insolubles- Isolation & concentration of product- Purification- Polishing

A) Pretreatment (cell disruption)

- Necessary for recovery of intracellular materials

B) Removal of insolubles (solid/liquid separation)

(filtration, sedimentation, centrifugation)

- Removal of cell debris etc- Relatively little product concentration @

improvement of product quality occurs


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C) Isolation & concentration of product

(adsorption & solvent extraction)

- Relatively non-specific, remove materials of widely

divergent properties compared to the desired product.

D) Purification (chromatography, membrane

filtration, osmosis, electrically enhanced

bioseparations)

- highly selective- remove impurities of similar chemical

functionality and physical properties

E) Polishing (crystallization, drying)

- Provide the desired product in a form suitable forfinal formulation & blending for direct shipping.

-

Most products must also be dried.


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n/t: Biggest increase in concentration in isolation

step; biggest in quality during purification.

6) Although only one component, the product is

usually wanted, several components need

separating.

7) Example of such products are cells, water, cell

debris, nucleic acid polymers, added salts, and the

remainder of the proteins.

8) chemical process vs fermentation


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Chemical process Fermentation

Component Unreacted substrate,

byproduct, catalyst,

solvent

Unconsumed substrate,

various metabolic

byproducts (from different

pathways), many others like

mineral for the survival of

the cell

9) intracellular vs extracellular


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F) Yield

1) As far as possible, the bioseparation should be

achieved with fewest processing steps (generally 6 to

7 steps are used)

2) The overall yield of an n-step process with step

yield of x percent is (x/100)n. Therefore n must be

minimized for a high overall yield.

3) Example

Calculate the overall recovery for a train of 5 steps,

each with 90% step yield.

G) Example (Process)


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G) Epilogue

Non-conventional Bioseparation

Combination of reaction & separation

bioprocess lecture 1

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