Fermentation types.. For msc students

1. Aerobic fermentation
Anaerobic, Batch, Continuous
fermentation
By
Harinatha Reddy A
Department of Biotechnology
biohari14@gmail.com

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3.  The term “Aerobic fermentation” is misnamed because
fermentation is an anaerobic process.
 Simply, this is a process of burning simple sugars to energy in cells;
more scientifically, it can be called aerobic respiration.
 Yeast cell ferment glucose in the presence of oxygen and without
oxygen.

Aerobic Fermentation:

4.  The key difference between aerobic and anaerobic fermentation
is that aerobic fermentation uses oxygen whereas anaerobic
fermentation does not use oxygen.

5.  Aerobic” fermentation means that oxygen is present.
 Wine, beer and acetic acid, vinegar need oxygen in the “primary”
or first stage of fermentation.
 When creating vinegar, for example, exposing the surface of the
vinegar to as much oxygen as possible, creates a healthy, flavourful
vinegar with the correct pH.

6. Anaerobic fermentation:

7.  Fermentation is a metabolic process that consumes sugar in the
absence of oxygen.
 The products are organic acids, gases, alcohol, lactic acid.
 It occurs in yeast and bacteria, and also in oxygen-starved muscle
cells, as in the case of lactic acid fermentation.
 In 1857, Louis Pasteur concluded that alcoholic fermentation can be
caused by living yeast under anaerobic conditions.

8. 1. Ethanol fermentation
2. Lactic acid fermentation
3. Methane gas production in fermentation
 In methane gas production Acetic acid can undergo reduction by
Methanogenic bacteria and produce methane and carbon dioxide:
CH3COO− + H+ → CH4 + CO2
 The reduction of carbon dioxide into methane in the presence of
hydrogen can be expressed as follows:
CO2 + 4 H2 → CH4 + 2H2O

10. Batch Fermentation:

11. Batch Fermentation:
 A batch fermentation is regarded as a
closed system.
 The fermenter is first filled with the raw
material (carbon source).
 Then the microbes are added and
allowed to ferment of the raw material
under optimum pH and Temperature.


12.  The products remain in the fermenter until the completion of
fermentation.
 After fermentation, the products are extracted and the fermenter is
cleaned and sterilized before next round or batch.
 Thus here the fermentation is done as separate batches.

13.  Setup is not changed from outside once the fermentation is started.
 Nutrients are added only in the beginning and not added in between
the fermentation process.
 Environmental conditions in the fermenter will not be constant.

14.  Relatively larger size fermenters are used.
 Suitable for the production of secondary metabolites whose
production is not associated with the growth of the microbes.
Example: antibiotics
 Less investment required.
 Chance of contamination is less.

15. Under optimal conditions there are four typical phases of
growth was observed in batch fermentation:
 Lag phase
 Log phase or Exponential phase
 Stationary phase
 Death phase

16. Lag phase:
 No cell division and there is no net increase in mass, But cells
increase in size.
 The cells are synthesizing new components.
 Lag phase also know as Phase of cell enlargement or Preparation
phase/cell adjustment phase.

17. Log phase:
 Microorganisms are dividing at the maximal rate .
 Their growth rate is constant during the log phase.
 The population is most uniform in terms of chemical and
physical properties during this phase.
 Cells are small in size, and produce primary metabolites.

18.  In the stationary phase the total number of viable
microorganisms remains constant. This may result from a
balance between cell division and cell death.
 In this phase bacteria growth rate is decreases, Due to the,
deposition of toxic waste products and empty of nutrients.
 The secondary metabolites are produced in this phase.
Stationary Phase:

19. Death Phase:
 The number of viable cells are decline death phase.
 Environmental changes like nutrient deprivation and the buildup
of toxic wastes lead to the decline in the number of viable cells.

20. FED BATCH FERMENTATION:

21. fed batch fermentation:
• Fed-batch fermentation defined as an operational technique in
biotechnological processes where one or more nutrients
(substrates) are fed (supplied) to the bioreactor during cultivation
or fermentation.
• FBF is Semi-closed type………but not semi continuous.
• Periodical substrate addition prolongs log and stationary phases.

22.  It is difficult to measure substrate concentration in fed
batch fermentation.
 But production CO2, Tmp and Changes in pH may be measured.
 Addition of substrates (Carbon and nitrogen and trace metals)
increases the product yield.
 Fed-batch fermentation has become popular for the production of
alcohol and recombinant proteins.

23. Product inhibition:
 End products of fermentation such as methanol, ethanol, acetic
acid and lactic acid inhibit the growth of microorganisms.
 By adding such substrates or nutrients to fermenter properly log-
time can be increase the cell growth.

24. Characteristics Fed-batch culture
Cultivation system Semi-closed type
Addition of fresh nutrition Yes
Volume of culture Increases
Chance of contamination Maximum
Log phase longer
Product yield High

25. Semi Continuous fermentation:

26. Semi Continuous fermentation:
 In semi-continuous fermentation, a portion of the culture medium
is removed from the bioreactor and replaced by fresh medium
(identical in nutrients, pH and temperature etc.).

27.  In the semi-continuous fermentation, the lag phase and other
non-productive phases are very much shortened.
 The product output is much higher compared to batch culture
systems.
 Semi-continuous fermentation technique has been successfully
used in the industrial production of alcohol.

28.  These include the technical difficulties of handling bioreactors.
 Addition of nutrients that may cause contamination and
changes in physiological and metabolic characters of
microorganisms.
Disadvantages of semi-continuous fermentation.

29. Continuous culture or Continuous fermentation:

30. Continuous culture or Continuous fermentation:
 In Continuous fermentation the fresh medium is continuously
added and metabolic end products and microorganisms are
continuously removed at the same rate.
 It is an open system.
 Here the log phase of the microbes is maintained in the fermenter
for prolonged periods of time in by the addition of fresh media
are regular intervals.

31.  The continuous fermentation process never stops in between and
it continues to run for a long period of time with the addition
of nutrients and harvesting the metabolites at regular intervals.

32.  Nutrients are added many times (in the beginning and in between
the fermentation process).
 The process is not stopped for the collection of the products, but
it is continuously taken out from the fermenter.

33.  Smaller size fermenter is required.
 The yield of the product is very high.
 Environmental conditions (pH, Tmp, con.CO2) in the fermenter will be
kept constant.
 Suitable for the primary metabolites whose production is associated
with the growth of the organism.
 Example: organic acids, amino acids.

34.  Less commonly used for large scale production.
 Chance of contamination is more.

35.  Two types of Continuous bioreactors:
1. Chemostat bioreactors
2. Turbidostat bioreactors

36. Chemostat bioreactors:
 A chemostat is a bioreactor to which fresh medium is continuously
added, and metabolic end products and microorganisms are
continuously removed.
 One of the most important features of chemostats is that
microorganisms can be grown in a physiological steady state
under constant environmental conditions and culture parameters.

37.  Chemostats are frequently used in the industrial manufacturing
of ethanol.
 Chemostats in research are used for investigations in cell
biology, as a source for large volumes of uniform cells or
protein.
 Chemostats can also be used to enrich specific types of
bacterial mutants in culture such as auxotrophs.

38. Turbidostat bioreactors:
 A turbidostat is a continuous fermentation device, similar to a
chemostat.
 In this case turbidity measurement is used to monitor the addition
of nutrients, removal of end products and biomass concentration.

40. Applications of continuous fermentation:
 Continuous fermentation process have been used for the
production of antibiotics, organic solvents, single cell protein,
ethanol and waste water treatments.

41. Advantages of continuous fermentation:
 The size of the bioreactor are smaller than compared to batch
fermentation.
 The yield of the product is constant.
 Continuous fermentation may run continuously for a period of
30 to 40 days.

42. Disadvantages:
 It is not used widely in industries.
 Maintenance of sterile conditions is difficult.
 Nutrient variations also alter the growth and physiology of the cells
and product yield.

43. Or Increase

44. Thank you