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SCALING UP OF
BATCH
STERIALISATION
Batch culture: Growth Kinetics
During log phase growth reaches maximum (max)
After depletion of substrate, growth rate decreases and finally ceases
m = m max s
(Ks +s)
m
m= specific growth rate
m max
1/2
m max
Ks = substrate concentration
Residual substrate conc. [s]
As growth increases biomass increases: during log phase
dx = mx
dt
1
dx. 1
dt x
x = cell conc (biomass) (mg/m3)
t = incubation time (h)
m = specific growth rate (h-1)
=m
dx
dt
m =slope
x
Beginning of log phase t=0 biomass X0
On integration of equation 1
∫dx
x
= ∫ mx
Loge X = mt + K (integration constant)
2
when t=0
Log X0 = K
put this value in equation 2
loge X = mt + loge X0
Loge X –loge X0 = mt
ln X
X0
= mt
ln X . 1 = td
X0 m
3
When
t = td
X = 2X0
Then
ln X . 1 = td
X0 m
ln 2X0 . 1
X0 m
ln 2
m
= td
= td
0.693 = td
m
m
= 0.693
td
m is inversely proportional to td
If td is high m is low and vice versa
X0 cells inoculated at time t0
X cells at time t
dx = mx
dt
Can be written as equation 3
ln X
X0
= mt
ln X –ln X0 = mt
Converting natural log
(log10 X –log10 X0) 2.303 = mt
(log10 X –log10 X0) 2.303 = tt-t0
m
(log10 X –log10 X0) 2.303 = m
tt-t0
m = m max s
(Ks +s)
m= specific growth rate
m
m max
1/2
m max
Ks = substrate concentration
Residual substrate conc. [s]
Disadvantages of batch
cultures
Temperature of batch culture cannot be
increased beyond 121oC
 In case increased
 Heating & cooling periods will increase
 Degradation of nutrients

Problem overcomed by switching to continious
sterialisation because
 Media to be sterialised is dealth in small
increments
 Shorter heating & cooling period
 Lesser nutrient degradation
Development of industrial
fermentation processes
•
•
•
•
•
Money making
Competition
Economically feasible on large scale basis
Recovery of product ready for open market
Competitive advantage
What are the R&D approaches for finding of a MO of
economic value, and large scale fermentation
process?
Micro-organism
Stock culture
collections
Source
Screening
Primary screening
Secondary screening
Environment (soil)
Preservation of Industrially
important MO
• Viable and Free from contamination
• Stored in such a way so as to eliminate genetic change and retain
viability
• Viable by repeated sub-culture (avoid mutations by keeping stocks
and strain degeneration and contaminations)
Preservation of Industrially
important MO
1. Storage at reduced temperature
a.
Agar slopes at 50C or in -200C freezer: viable for 6 months
b. Liquid nitrogen (-1960C): problems of refilling, advantages
2. Storage at dehydrated form
a.
Dried cultures
b. Lyophillization
Quality control of preserved stock: batch system, single colony,
typical pattern, large number, purity, viability and productity
If sample fails entire batch is destroyed
Types of Low molecular weight compounds by MO
SUBSTRATE
Primary
metabolites
Secondary
metabolites
Antibiotics
Essential metabolites
Amino acids
Nucleosides
vitamins
Ethanol, acetone, lactic
acid, butanol
Steroids
Amino acids
Alkaloids
Gibberlins
Pigments
Metabolic end products
Bioconversions
Ascorbic acid