Sci

1. Advances in Fermentation
"The role of the infinitely small in nature is
infinitely large"
- Louis Pasteur

2. Definition
Fermentation
- Traditionally, defined as the process for the production of alcohol or
lactic acid from glucose.
- Broadly, defined as “an enzymatically controlled transformation of
organic compound” (Webster’s New College Dictionary)
• Biotechnology
- Traditionally, implies the use or development of methods of direct
genetic manipulation for a socially desirable product.
- Broadly, “Commercial techniques that use living organisms, or
substances from those organism, to make or modify a product…”
(Congress of the United States, 1984)

3. • Fermentation has always been an important part
of our lives
– products for use by humans
– foods spoilage by microbial fermentations
– foods be made by microbial fermentations
– Fermentation could be called the staff of life because it gives us
the basic food: bread, idli
– muscle cells use fermentation
• But how fermentation actually works was not
understood until the work of
Louis Pasteur

4. • What is fermentation?
• For a cell, fermentation is a way of getting
energy without using oxygen
• In general, fermentation involves the breaking
down of complex organic substances into
simpler ones
• Commonly used to describe the
production of biomass or specific
molecules in vessels
• Fermentation is the process that produces
alcoholic beverages or acidic dairy
products
• Fermentation products have value

5. Fervere (L)
Yeast - fruit juice - wine
Brewing beer - CO2
Baking bread, alcohol
Egyptians used yeast in 1500 B.C.
1915-1920 Baker’s Yeast
Early farmers cultivated wheat, barley, and possibly rye
9000 B.C. - Drawing of cow being milked
Yogurt - 4000 B.C. Chinese
Cheese curd from milk - 5000-9000 years ago
Fermented dough was discovered by accident
when dough was not baked immediately
Fermented beverages
Beer making began as early as 6000-5000 B.C.
Egypt ~5000 B.C made wine from grapes
Barley malt – earthenware - Yeast found in ancient
beer urns
Monasteries - major brewers
1680 - Leeuwenhoek observed yeast
Between 1866 and 1876 - Pasteur

6. Classical Fermentations
Describes the development that fermentation has taken
place from ancient times to the present
Top fermentation - developed first, yeast rise
to top
• 1833 - Bottom fermentation - yeast remain
on bottom
• 1886 – Brewing equipment made by E.C.
Hansen and still used today
• World War I – fermentation of organic
solvents for explosives (glycerol)
• World War II – bioreactor or fermenter
•Antibiotics
•Cholesterol – Steroids
•Amino acids

7. Classical biotechnology advances
• In the 1950’s, cholesterol was converted to cortisol and
hormones by reactions such as microbial hydroxylation
(addition of -OH group)
• By the mid-1950’s, amino acids and other primary
metabolites (needed for cell growth) were produced, as
well as enzymes and vitamins
• By the 1960’s, microbes were being used as sources of
protein and other molecules called secondary
metabolites (not needed for cell growth)
• Today many things are produced:
– Pharmaceutical compounds such as antibiotics
– Amino Acids
– Many chemicals, hormones, and pigments
– Enzymes with a large variety of uses
– Biomass for commercial and animal consumption
(such as single-cell protein)

8. World Market for Some
Products of Enzymatic
Reactions
High fructose corn syrup: $ 1 bil.
Aspartame: $ 850 million
Acrylamide: $ 300 million
Food and starch
processing: 45%
Detergents:
34%
Textiles:
11%
Leather:
3%
Pulp and paper:
1.2%

9. Chemical Vs Biolog (chem) ical

10. Typical Bioprocess
Stock culture
Shake flask
Seed fermenter
Raw materials
Medium formulation
Sterilization
Computer control
Production fermenter
Air
Recovery
Purification Products
Effluent treatment
Microorganism
cell preparation
Medium
preparation

11. Upstream -Downstream

12. Cell culture
Enzymatic
Feedstock Bioprocessing Product
GAS
LIQUID
SOLID
PRODUCT
LINES
Biocatalyst Bioreactor
Recovery
product
Feedstock Biochemical processing
 Gas
− Syn. Gas
− CO2
− Organic vapor
 Liquid
− Organic
− Sugar solution
 Solid
− Biomass
− Consumer Waste
 Immobilized Enzymes
− Ambient to Extreme
 Fermentation
− Immobilized
− Free cell
− Ambient to Extreme
 Bioreactors
− Continuous Systems
− Membrane
− Batch or Fed-batch
 Separation
− In situ
− Secondary
 Media
− Gaseous
− Aqueous
− Organic
 Pharmaceuticals
 Fine chemicals
 Specialty Chemicals
 Feedstock
 Bulk chemicals
General Bioprocess
Product

13. Range of fermentation
produce microbial cells – yeast
produce microbial enzymes – amylase
produce microbial metabolite
•primary metabolite: alcohol, organic acids, AA
•secondary metabolite: bacteriocins, antibiotics
produce high-value compounds –
hormones
Processes producing transformed
products
produce genetically modified products

14. •use dissolved
substrates or solid
substrates suspended
in a large amount of
water (e.g., wine,
yoghurt, antibiotics)
Submerged
fermentations
•microorganisms grow
on a moist solid with
little or no free water
(sausage, salami,
mould-ripened
cheeses, enzymes)
Solid state
fermentation

15. Solid state fermentations
• Substrate characteristics
o Water activity
o Particle size
o Substrate pH
• Aeration and agitation
• Heat transfer

16. Types of fermentations….
• Aerobic processes
o e.g., submerged culture - citric acid
production
• Anaerobic processes
o Solid state, e.g., Fermented meat
products
o Submerged, e.g., yoghurt, solvents
Aerobic
C6H12O6 + 6O2
___> 6CO2 + 6H2O
Anaerobic
Yeast:
C6H12O6
___> 2C2H5OH + 2CO2
Acetobacter aceti:
C2H5OH ___> CH3COOH + H2O

17. Types of fermentations ….
Single species fermentations (aseptic)
• May use sterile substrate
Most food fermentations are non-sterile (non-
aseptic)
• Require participation of several microbial species, acting
simultaneously or sequentially
• Modifications of culture environment (salt content, pH, water
environment) allow selection of desired microorganisms
• Controlled starter cultures (single strain or multi strain versus
“wild fermentations”)

18. Microbial growth during
fermentations

19. Submerged fermentations
• Batch culture
• Fed-batch culture
• Continuous culture

20. Batch Culture
• Nominally a closed system
• Medium and inoculant are placed in fermenter and left
until harvest
• At end of fermentation period fermenter is emptied and
product is harvested
Advantages to Batch Culture
• Simple system
– once sterilized unlikely to become
contaminated
– lower cost equipment
• Uniformity of production - consistency
Disadvantages to Batch Culture
• Lag time
• Toxin buildup
• Limited production potential for many
products

21. Continuous Fermentation
• Open system
• New media enters, old media leaves
• Gas exchange is possible
• Allows for extended growth and production
• Producing organism can be removed with the
old medium
Advantages to Batch Culture
• Extracellular compounds
• Continuous monitoring and modifying culture
environment
• Useful when production of molecule is not
developmentally regulated
Disadvantages to Batch Culture
• Expensive to operate
• More difficult to maintain sterility
• Little value if product is not secreted or not present
for an extended period of time in the cell

22. Immobilized Fermenters
• Open system
• Organisms are cultured within a matrix so that they are removed with the old
medium
• Generally used for bioconversions
Limitations
• Slow flow rates necessary
• Not all precursor molecules will be converted
• Limited organism growth - restrained within matrix

23. biocatalyst
environment
downstream

24. A Typical Fermentation Process
Feed
Acid
Alkali
Motor
DOT
Temp
pH
Speed
P
P
Press
Gas
Shake flask Seed culture Fermenter Filter Cooler Holding tank