Batch and continuous culture are two common methods for cultivating microorganisms. Batch culture involves inoculating microbes into a closed vessel containing growth medium. As nutrients are consumed, the culture progresses through lag, exponential, stationary, and death phases. Continuous culture maintains microbes in a steady state by regularly replacing spent medium with fresh medium using systems like chemostats and turbidostats. This allows for constant growth rates and tighter environmental control. Kinetics models can describe microbial growth in continuous culture using parameters like dilution and specific growth rates.

1. Presented by
Arantha. J. joseph
M. Pharm
Pharmaceutics
1
CONTINUOUS CULTURE
BATCH CULTURE
AND
KINETICS

2. INTRODUCTION
• Agent Org substance Simple substances.
• large scale production tanks( fermenters ).
• 3 Stages .
• The organisms are maintained at a required temperature, PH,
oxygen & substrate concentration.
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3. • The growth of microorganism can be achieved by 3 ways.
Batch culture.
 Continuous culture.
 Fed batch culture.
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4. Batch culture
• Closed culture system.
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5. 5
Sparger to increase
efficiency of aeration
Air in
Air out
Air filter
Syringe for
withdrawing
samples
Syringe for adding
buffer, nutrients
etc.
Air filter
Culture
medium
Nutrients given to these
organisms are utilized for
the reproduction and
accumulation of metabolic
products.

6. • Eventually conditions in the culture will become too unfavourable
for the organisms to survive, and the population will die out.
• School-based experiments on microbial growth.
• Used industrially in many processes that harvest the secondary
metabolites of micro-organisms (such as antibiotics).
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7. • The various phases includes,
1. Lag phase
2. Accelerated growth phase
3. Exponential growth phase
4. Decelerated growth phase
5. Stationary phase
6. Death phase
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8. Lag phase
 Initial period of cultivation.
 change of cell number is zero or negligible.
 Even though the cell number does not increase, the cells may grow in
size during this period.
 When cells are placed in the fresh medium, the intracellular
concentrations of cofactors, amino acids, ions will decrease and these
have to be synthesized / transported first before cell division to occur.
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9.  When the cells are inoculated into medium containing different
carbon source enzymes for its metabolism have to be
transported.
 Diauxic growth.
 When glucose and lactose are present then glucose will be utilized
first then lactose.
 Presence of glucose will have catabolite repression on galactosidase
enzyme which is required for lactose utilization.
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10. Accelerated growth phase
 At the end of Lag phase.
 when growth begins the division rate increase gradually and
reaches a maximum value.
 Growth rate increases to maximum in this phase.
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11. Exponential growth phase
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X
dt
dX 
 Cell division occurs in this phase.
 Often cell dry weight is used for cell concentration.
 Exponential phase we write as
 where µ - Specific growth rate
X- cell dry weight

12. Other phase
• The end of the exponential phase occur when any of the essential
nutrients is depleted or toxic metabolite accumulated in the system.
During this phase the growth rate declines.
• Stationary phase will follow this phase. The length of stationary phase
may vary with cell type, previous growth conditions etc., In certain cases
the product formation will occur during this phase
• Following this is the death phase where the cells will start to lyse and the
cell density decreases.
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13. Advantages of batch culture
 The culture is easy to set up.
 The environmental conditions are easy to control.
 The types of vessels used can be used for different processes at
different times.
 If the culture becomes contaminated, only one batch that is lost.
 The level of nutrients drops, which can create the conditions necessary
for the microorganism to manufacture secondary metabolite such as
penicillin.
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14. Continuous culture
 Steady state by regularly replacing a portion of the used or spent
medium by the fresh medium.
 Open type: Both cells & used medium are taken out and
replaced by the fresh medium of equal volume.
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15. 15
• The open cultures are of ,
1) Turbidostat
2) Chemostat.
3)Plug flow reactor.
• In a Turbidostat, cells are allow to grow up to a preselected
turbidity, when a predetermined volume of culture is replaced by
normal culture medium.

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17. MEASUREMENTOF TURBIDITY
 Manual cell counting.
 plating and CFU counting.
 Coulter counter.
 spectrophotometer
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A picture of Staphylococcus aureus colonies
growing on an agar plate (transmitted light).
Such homogeneously spread colonies are
suitable for CFU enumeration
The electrode of a Coulter counter

18. Chemostat
• In a chemostat, a chosen nutrient is kept in concentration so that it is
depleted very rapidly to become growth limiting,
• While other nutrients are still in the concentrations higher than
required.
• In such a situation, any addition of growth limiting nutrients is
reflected the cell growth.
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• Chemostat are ideal for the determination of the effects of
individual nutrients on the cell growth and metabolism.

19. • In batch culture, all the cells are not in the identical physiological state.
• The effect of chemical substances and physical conditions on the
organisms is not identical in all phases of growth.
• The growth rate of a culture and so its physiological conditions may be
maintained constant by the process of continous culture, usually in a
Chemostat.
• The level of the growth is controlled by maintaining a fixed limiting
concentrations of particular nutrient.
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21. Advantages of continuous culture
• It can be carried out in smaller vessels (productivity high)
• The high productivity for biomass.
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22. Disadvantages of continuous culture
• Microbial growth, clumping of cells and foaming tend to block
up inlet pipes.
• Can be difficult to control all the environmental factors –
could lead to considerable amount of waste.
• Not possible to create the low-nutrient, high-stress conditions
under which secondary metabolites such as penicillin are
produced.
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23. KINETICS OF CONTINUOUSCULTURE
• Chemostat is usually operated at different dilution rates.
• The dilution rate is the ratio of inflowing amount of nutrient medium
per hour to the volume of culture.
• The dilution rate D=F/V
D=Dilution rate, F = Flow rate, V = Volume
• The change in the cell concentration in the fermenters in a given
period becomes,
dx/dt = growth – output
dx/dt = µx - Dx 23

24. • Medium is added continuously at a suitable rate and displacement of culture is
balanced by the production of new biomass.
• The steady state can be expressed as ,
dx/dt = 0
µx = Dx
µ = D ………………………….. ( 2)
• The steady state in a system is controlled by the flow of medium through the system
( dilution rate ).
µ = µmax S/Ks+s
From the equation 2, µ =D.
So, D = µmax/Ks’+s’ ……………… (3) 24

25. • s’ = Steady state residual conc. in the medium.
s’ = KsD/µmax-D………………………... (4)
• The substrate conc. in the chemostat is determined by the dilution
rate.
• The concentration of the cells in the system at steady state
X’= Y(Sr – s’) ………………………(5)
• From 4 &5, we get
X’ = Y(Sr – KsD/ µmax - D )
• Sr&D is the operational variables which control the steady sate of
biomass concentration.. 25

26. REFERENCES
• Industrial microbiology by L.E CASIDA, JR page number 165-174.
• Pharmaceutical biotechnology by Purohit page number 188.
• Industrial microbiology by A.H PATEL page number 224-231.
• Pharmaceutical Biotechnology. Fundamentals and applications by S.S
Kori, M.A Halkai.pg-135-156.
• Principles of Fermentation technology, 2nd edition by P.F.Stanbury ,A.
Whitaker, S.J Hall. Pg no. -13-21.
• WWW.Slide share . [may 2017]
• WWW.Wikipedia.org [may 2017] 26

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