1. Lec # 8 Fermentation biotechnology
Dr. Shah Rukh Abbas

2. Fermentation Definition by biochemist by indusrial users
anaerobic process that generate energy by the breakdown of organic compounds.
Any process that generate bacterial metabolites as end products: lactic acid, enzymes, ethanol, butanol, and acetone.
by indusrial users
Any aerobic process that produces microorganisms (biomass)as the end product.
Biotransformation--transformation of a compound by microbial cells

3. Industrial biotechnology, application of modern
biotechnology for industrial production, is always
referring to Fermentation technology.
Less waste generation
Reduced energy consumption
Fermentation biotechnology involves partnership between
Molecular biologists; responsible for isolating, characterising, modifying and creating effectively expression of industry desirable genes
Biochemical engineers; to ensure that the GE of microorganisms can be grown in large quantities under the conditions that give optimal product yeild.

4. Bioreactor (Inductrial fermenters)
Aerobic and anaerobic microorganisms are cultured under controlled conditions in large chamber called bioreactor or fermenter.

5. Steps involved in fermentation
Sterilization of fermenter and associated equipment.
Preparation and sterilization of the culture medium
Preparation of the pure culture for inoculation of the medium culture in the fermenter vessel
Cell growth and synthesis of the desired product under a specific set of conditions.
Product extraction and purification or cell collection
Disposal of expended medium and cell, and cleaning of the bioreactor and equipment

6. Principle of fermentation
Fermentation technology is linked with the improved productive performance of microorganism by optimizing their growth conditions.
Scale-up is not just a mere multiplication of growth culture; the optimum conditions for a 200mL culture won’t be same as for 10,000 L culture.
A number of parameters must be precisely regulated to obtain maximum yeilds either from small (1-10L) or large (>1000L) bioreactors.

7. General factors of industrial fermentation
Most of the organism used in fermentation are aerobic; because aerobic metabolism is more efficient than anaerobic metabolism.
Oxygen demand
consistent pH
temperature control
Rate and nature of mixing
a supply of nutrients for rapid growth
antifoaming agent to alleviate excess foaming
Moreover, optimal conditions generally change with each 10-fold increase in the volume of a bioreactor.

10. Bioprocess/ Bioreactor: Bioreactor design and process control
Industrial fermentation process is generally divided in to three stages:
Upstream : First step in which biomolecules are grown (innoculum development, media formulations, shake flasks experiements etc.)
Bioprocess/ Bioreactor:
Bioreactor design and process control
Downstream:
A process to obtain the product
Upstream
Bioprocess
Downstream

11. Methods used to collect products and cells from fermenters
Depends on the principle of microbial growth
Microorganisms can be grown in
Batch fermentation
Fed-Batch fermentation
Continuous fermentation

12. I. Batch fermentation
In batch fermentation, the sterile growth medium is inoculated with the appropriate microorganisms, and the fermentation proceeds without the addition of fresh growth medium.
(1) The composition of culture medium, the concentration of microorganisms, the internal chemical composition of the microorganisms and the amount of metabolite are all change during fermentation. (2) All 6 phases of bacterial growth cycle are observed.

13. II. Fed-Batch fermentation
In fed-batch fermentation,
fresh growth medium is added continuously during fermentation, and no growth medium is removed until the end of the process.
(1) The continuous addition of medium prolongs both the log and stationary phases, thereby increasing the biomass and the amount of metabolites. (2) However, microorganisms in stationary phase often produce proteolytic enzymes (proteases) to degrade proteins. (3) A fed-batch fermentation strategy can increase the yield from 25% to more than 1,000% compared with batch fermentation.

14. III. Continuous fermentation
In continuous fermentation, fresh growth medium is added continuously during fermentation, but there is also continuous removal of an equal volume of medium containing suspended microorganisms.
(1) A steady-state condition of the total number of cells and the total volume in the bioreactor is maintained. (2) A single reaction can be maintained for a much longer period. (3) However, potential drawbacks are loss recombinant plasmid constructs in some cells, difficulty in maintenance of an industrial scale and variation from batch to batch.

15. Types of bioreactors/fermenters
There are 3 fundamental classes of bioreactors
Stirred-tank reactors (STRs),
Bubble columns and
Airlift reactors.
STRs:
(1)        STRs have internal mechanical agitation and are the most commonly used.
(2)        STRs are usually constructed from stainless steel or glass for laboratory-scale.
(3)        Heat generated from metabolism of the growing cells or the energy input by agitation is a limitation of the size of a bioreactor.

16. B. Bubble columns: C. Airlift reactors:
(1)        It relies on the introduction of air or another gas for agitation.
(2)        The smaller air bubbles introduced under high pressure near the bottom become larger ones as they rise through the column, leading to uneven gas distribution.
C. Airlift reactors:
(1)        There are two main types: internal-loop reactors and external-loop reactors.
(2)        The motion of an introduced air causes density differences within the different parts of the bioreactor.
(3)        Internal-loop airlift reactors are simple in design, but both the volume and the circulation rate are fixed once they are constructed.

17. (4)        External-loop airlift reactors can be easily changed or modified by altering its volume to suit the requirements of different fermentations.
(5)        Airlift bioreactors are generally more efficient than bubble columns.

18. Types of bioreactors/fermenters
Stirrer Tank
Reactor
Bubble column
reactor
Air lift
reactor

19. Internal and external loop air lift bioreactor

20. Solid Substrate Fermentation
Microorganism are grown on solid substrate that are not submerged in liquid media
Oxygen is more readily available to the cell as they are direct in contact with it
Product recovery is much easy in this procedure
corn-soybean meal based diets
By Solid substrate fermenter for animals

22. Single Cell Protein
A monoculture of algal, bacterial or fungal cell has a protein content that is 70-80% of its dry weight
When such culture are grown in large volume for use as human or live stock feed supplements, it is called single cell protein
SCP is rich in nutrients as minerals, vitamins, carbohydrates, lipids as well essential amino acids like lysine and methionine which are absent in plant protein

24. Single Cell Protein
SCP is produced by using inexpensive substrate to supply nitrogen and carbon
For example carbohydrate containing raw materials, waste from cheese production and pulp mils
SCP may contain toxic compound
Nucleic acid, hepatoxins, heavy metals absorbed from the substrate
Effective research is needed to remove these toxic compound from SCP