FERMENTATION

DR. TIJANI A. S.

Learning Objectives:

After this topic, student will be able to:

Describe fermentation

Explain fermentation techniques

Describe types of fermentation

Know applications of fermentation

Fermentation

Fermentation is characterized by the metabolic processes that are used to transfer electrons

released from nutrients to molecules obtained from the breakdown of those same nutrients.

Fermentation utilizes numerous organic compounds, such as sugars, as endogenous electron

acceptors to promote the electron transfer that occurs.

Fermentation includes the processes by which energy is extracted from the oxidation of organic

compounds. The oxidation of organic compounds occurs by utilizing an endogenous electron

acceptor to transfer electrons released from nutrients to molecules obtained from the breakdown

of these same nutrients.

Fermentation

The international use of fermentation technology for large scale production of

microbial biomass or metabolites is called Industrial fermentation.

Fermented products have immense use in food, medicine and other industries.

Modern industrial fermentation units use genetically engineered microbes for the

production of desired metabolites

Types of Fermentation

Batch fermentation

Continuous fermentation

Fed-batch fermentation

Types of Fermentation

Batch fermentation

Product of growth can be biomass or metabolites

The nutrient environment in the fermenter is continuously changed

Change in the environment in the fermenter enforce change in the metabolism of the

cells

Results in cessation of cell multiplication

Microbes in the batch culture show the following pattern of growth with distinct

phases

Lag phase: microbe adapt to the environment

No apparent growth.

Exponential phase: microbial growth proceeds at the maximum rate

Stationary phase: no overall growth most of the secondary metabolites are

produced

Death phase: no growth at all, cells start to die and their population decreases,

fermentation stops before the death phase

Types of Fermentation

Continuous fermentation

Substrate is added continuously to the fermenter, and biomass or products are

continuously removed at the same time

Under this condition the cells remain in logarithm phase of growth

Used for production of some primary metabolites (e.g, ethanol and organic acids), in

waste water treatment, and fermented foods and for the production of monoclonal

antibodies and recombinant proteins by animal cell cultures.

Types of Fermentation

Fed-batch fermentation

Is a modified version of the batch fermentation

The culture is fed with fresh nutrient medium without removing the growing

microbial culture

Allows one to supplement the medium with such nutrients that are depleted or that

may be needed for the terminal stages of the culture.

this periodical addition of the nutrients prolong the log and stationary phases of the

microbes in the fermenter and

Results in the rapid increase of biomass and subsequent increased production of

metabolites in the stationary phase

The range of fermentation

There are five major groups of commercially important fermentations:

Those that produce microbial cells (biomass production) e.g Yeast

Those that produce microbial enzymes e.g glucose isomerase

Those that produce microbial metabolites e.g. antibiotics (penicillin), vitamins

Those that produce recombinant products e.g insulin, human therapeutics, amino acids

Those that modify a compound which is added to the fermentation in the transformation

process

Applications

Fermentation process is used:

Applications

Other applications include:

8. To produce antibiotics and other related products

9. To produce ethyl alcohol used as gasohol

10. To produce alcoholic beverages like beer and wine

11. Yoghurt is produced from milk

12. Cheese is also produced by fermentation of milk

References

Pharmaceutical Biotechnology First edition by P. R Kavi Kishor, Maruthi Rao and I.

Sampath Kumar.

Advances in Applied Biotechnology Edited by Marian Petre