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FERMENTATION TECHNOLOGY

Fermentation - the process of chemical transformation of
organic substrate using enzymes of microorganisms
...

• Industries producing medicine, organic acids (butyric
acid, lactic acid, oxalic acid etc
...


Glycolysis and fermentation do not require oxygen (anaerobic)
...


Glycolysis: Embden-Meyerhof pathway
• Cytoplasm
• Anaerobic: Does not require oxygen
• Involves the splitting of a glucose molecule in a series of
ten steps which ultimately results in:
– two molecules of pyruvate
– and a net gain of two ATP
– and two NADH molecules

• The ten steps of glycolysis can be divided into three stages:
energy-investment, lysis, and energy-conserving

The 10 steps in Glycolysis
Energy investment stage:
• Step 1
...
The atoms of glucose-6-phosphate are
rearranged to form fructose-6-phosphate

• Step 3
...
Fructose 1,6-biphosphate is cleaved
form:
glyceralaldehyde 3- phosphate (G3P)
and dihydroxyacetone phosphate (DHAP)
• Step 5
...
Inorganic phosphates are added to the two G3P,
and two NAD+ are reduced to form 1,3-biphosphoglyceric
acid
• Step 7
...
The remaining phosphates are moved to the
middle carbons and a water molecule is removed from
each substrate to form phosphoenolpyruvic acid (PEP)
• Step 10
...
Two pyruvate molecules
are formed
Note: Glycolysis provides relatively small amount of energy (ATP & NADH)
...
Electrons are removed from NADH during
fermentation, producing NAD+ which is needed to keep glycolysis going
...

•
• It reduces 2 molecules of NADP+ to NADPH and nets a
molecule of ATP from each molecule of glucose
...

• It catabolizes glucose to pyruvic acid (utilised in Kreb’s
cycle for fermentation) using different enzymes from
those used in either glycolysis or PPP
• It yields precursor metabolites and NADPH, and a single
molecule of ATP for each molecule of glucose

•
•
•
•

Glycolytic
Cytoplasm
Anaerobic
Different enzymes
– Pseudomonas
– Enterococcus

• End products
–
–
–
–
–

2-1 = 1 net ATP
NADPH
NADH
2 Pyruvic acids
H2 O

Bacteria: Pseudomonas, Rhizobium, Azotobacter, Agrobacterium,
Enterococcus faecalis

Fermentation Pathways

– A process by which living cell is able to obtain energy via the
breakdown of glucose and other simple sugar molecules
without requiring oxygen
– Results in the production of energy in form of two ATP
molecules and produce less energy than the aerobic process of
cellular respiration
– Pyruvic acid is reduced to form reduced organic acids or
alcohols
...

– Gases (CO2 and/or H2) may be released
• Fermentation pathways are useful as tools in biochemical
identification
...


Fermentation = metabolism of pyruvate in the absence of oxygen
...
Very important
because NAD+ must be recycled for glycolysis
...

The products are used
in
diagnosis
...

The production of
butyric
acid
by
Clostridium
perfringens
causes
severe tissue damage
of gangrene

Lactic acid fermentation
...

(a) Homolactic fermentation
...
Occurs in
some types of bacteria called lactobacilli, in streptococci, and in
mammalian muscle cells
...


NADH from step 6 of glycolysis

NAD+ can now be reused in glycolysis,
step 6
...
e
...
Escherichia coli, Salmonella, Shigella
...
Pyruvic acid undergoes decarboxylation (CO2 is given
off) and reduction by NADH to form ethanol
...


Fig
...
coli; Salmonella; Shigella etc
...


Requirement for fermentation process
• Specific strain of microorganisms or its mutants
capable of showing fermentation efficiently at a
much faster rate
...


for

optimal

rate

of

TYPE OF FERMENTAION
1
...
SUBMERGED FERMENTATION
3
...
AEROBIC FERMENTATION
5
...
Examples of such fermentation are
mushroom cultivation, mold-ripened cheeses, starter cultures etc
...

• Traditional substrates are several agricultural products eg- rice,
maize, soy bean, cassava etc
...

• Such substrate selectively supports mycelial organisms, which can
grow at high nutrients concentration and produce a variety of
extracellular enzymes
...

• Some food fermentations involving SSF: Wheat by Aspergillus,
Soybean by Rhizopus, Soybean by Aspergillus
Phases of solid state fermentation
The are 3 phases:
1

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