The document discusses the use of bioreactors for plant cell suspension culture and highlights the importance of plant-derived compounds in pharmaceuticals and other industries. It explains the various bioreactor designs and their specific requirements to minimize shear stress and enhance nutrient availability, emphasizing the role of mixing and aeration. Various types of bioreactors, including airlift, bubble column, and photo bioreactors, are described, along with their operational considerations and implications for cell growth and metabolite production.

1. BIOREACTORS FOR
PLANT CELL
SUSPENSION CULTURE
GRACE FELCIYA S.J
FIRST YEAR
M.TECH – BIOPHARMACEUTICAL TECHNOLOGY
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2. Many thousands of chemicals are produced only in plants.
Only few % of the world’s plant have been scientifically
named and only few compounds have been screened for the
production of novel & useful compounds.
Around 120 drugs are derived from plants.
In western world around 25% of pharmaceuticals are derived
from extraction of plants.
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3. These compounds are chemically complex and non-
proteins, they have separate metabolic pathway.
Due to less knowledge on the metabolic pathway we
couldn’t enhance the metabolic products.
In order to increase this production, bioprocess was
introduced in plant cell cultures.
Some of the plant products :- dyes, food colours,
flavours, fragrances, insecticides and herbicides
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5. CHARACTERISTIC PLANT CELL SUSPENSION
Size 10-200 micrometer
Individual Size
Aggregates up to 2mm
generally form
Growth Rate
Slow, doubling time
2-5 day
Inoculation Density High, 10%
Shear Stress Sensitivity Sensitive and tolerant
Aeration requirement Low
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6. BIOREACTOR CONSIDERATIONS
All mode of cultivation system can be adopted to plant cells.
Plant cell are often found in groups which can alter in size during the
cell growth. Degree of aggregate formation is influenced by the degree
of mixing.
The large size, rigid cellulose based cell wall, and large vacuole make
the plant sensitive to shear stress. Therefore reactors with high shear
stress must be avoided.
Degree of mixing is necessary to achieve equivalent oxygen transfer or
equivalent shear changes from scale up, the degree of aggregation
and productivity may change.
Mixing depends on a combination of sparging & mechanical agitation.
Oversparging can be a problem for plant cell culture.
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7. BIOREACTOR CONSIDERATION
INDICATIONS
IMPLICATION FOR THE REACTOR
DESIGN
Lower respiration rate Lower O2 transfer rate required
More shear sensitive
Require operations under the low shear
conditions.
Cells often grow as aggregate or clumps
May have mass transfer limitations that
limit the availability of nutrient to cells
within the aggregate .
Degree of aggregation may be important
with regard to secondary metabolism
May be an optimal aggregate sizes for
product synthesis
Volatile compounds may be important for
cell metabolism eg. O2 or ethylene
May need to sparge gas mixtures
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8. GROWTH RATE
• Low growth rate increase productivity high biomass levels.
• At high cell densities the culture will be viscous and difficult to mix in
airlift bioreactor. However, for its particular nature, viscosity of plant
cell is low, and mixing in airlift Bioreactors is not greatly affected by
biomass up to 40gl-1
• Formation of dead zones where conditions are anoxic and cells settle
out is a problem.
TEMPERATURE
• Plant cell suspensions grow normally at 250C
• With the slow growth rate, heat input and cooling requirements are
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9. IMPELLER
• In microbial BR, impeller is used:
-to mix the culture
-to break up and distribute air bubble to increase oxygen transfer.
(main)
• With plant cell cultures, these roles are reversed owing to low O2
requirements and high settling rates.
• Mixing achieved under the restraint of shear sensitivity of plant cells.
• Due to shear sensitive of the plant cell culture, it is not suitable to use the
impellers.
• Another method that suitable for mixing of plant culture is by using the
airlift method.
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11.  Aeration – Agitation bioreactor
 Air driven bioreactor
 Rotating drum bioreactor
 Spin filter bioreactor
 Gaseous phase bioreactor
 Light introducing bioreactor(Photo bioreactor)
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12. • The aeration-agitation type bioreactors is widely used in small scale
experiments. However, when the culture volume is increased, many
problems arise in scale up, such as.
• 1.increasing mechanical stresses by impeller agitation
• 2.increasing foaming and adhesion of cells on the inner
surface of the bioreactor.
• Despite these problems, a large scale pilot bioreactor (volume 20 kl)
was constructed. It successfully produced both cell mass and
metabolites.
• This bioreactor is therefore the most important type for bioreactor
systems
AERATION- AGITATION BIOREACTOR
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13.  The simplest design is the air-driven bioreactor equipped with
sparger at the bottom of the vessel.
 It is widely used for plant cell, tissue, and organ cultures. In cases
where the cells grow rapidly and the cell mass occupies 40-60% of
the reactor volume, the flow characteristics become non-
Newtonian and the culture medium can no longer be agitated by
simple aeration.
AIR DRIVEN BIOREACTORS
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14.  In the early cultivation of plant cells, stirred bioreactors were
used with the impellers run at low speed.
 At 1970s, low shear airlift bioreactor develop.
 This was adopted as the bioreactor of choice.
 However, the use of high gassing rates to achieve good mixing
can have problems:
 Plant cell suspensions sensitive to the level of carbon
dioxide.
 Other essential volatiles such as ethylene can be stripped off
with high aeration rates.
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15. a)Draft-tube internal loop
configuration
b)Split cylinder device
c)External loop system
Continuous stirred tank reactor
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16. Alternative designs to the airlift and
stirred tank bioreactor have been used
in the cultivation of plant cells where
mixing or aeration is achieved at low
shear rates.
A bioreactor based on 2 concentric
rotating cylinders as been used to grow
Beta vulguris cells.
Aeration is provided by inner cylinder
which was gas permeable.
Mixing by vortices produced by Taylor-
Couette Flow.
TAYLOR-COUETTE FLOW
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17. BUBBLE COLUMN
• Cylindrical shape
• Axial flow (Eddies)
• Vertical baffle
• Gas is sparged at the base
• Movement of the liquid is caused by the density
differences
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18. SCHEMATIC DIAGRAM:BUBBLE COLUMN
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20.  Another bioreactor is designed to provide bubble-free aeration via rotating
coil of gas permeable membranes.
 It turns on rollers and the oxygen supply mechanism is entirely different from
either the mechanically agitated or the air-lift bioreactor
 It is suitable not only for the growth of plant cell, tissue, and organs but also
for the production of metabolites under high viscosity and high density
cultures.
ROTATING DRUM BIOREACTOR
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21. Alternative design, Spin Filter
Bioreactor has been successfully
used for carrot embryogenesis
where;
 Rotating filter mixed the culture
while allowing medium to be
added or removed from culture.
 The spin filter bioreactor will be
most suitable for the continuous
culture of plant cells.
SPIN FILTER BIOREACTOR
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22.  This type of bioreactor is equipped with filters on
which the culture is supported and with a shower
nozzle for spraying on the medium.
 Seed cultures are inoculated on the filters and
the medium is supplied to the culture by spraying
from a shower nozzle.
 The drained medium is collected on the bottom of
the bioreactor. This type of bioreactor is excellent
for plant cell, tissue, and organ cultures because
there is no mechanical agitation (e.g., driven
impeller, aerator) and, therefore, the growth rate
and the secondary metabolite production are
enhanced.
GASEOUS PHASE BIOREACTOR
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23. LIGHT INTRODUCING BIOREACTOR/PHOTO BIOREACTOR
Plants are susceptible to light irradiation and as a consequence various
metabolic and/or physiological changes are generated. Some important
reactions are
 Photosynthesis,
 Activation of specific enzymes such as phenylalanine ammonia lyase
(PAL) and to induce the production of flavonoids or anthodyanins
 Photomorphogenesis such as development of leaves
For these reasons introduction of light into the bioreactor is required.
A photo bioreactor is a bioreactor that incorporates a light source to provide
photonic energy input into the reactor.
Photo bioreactors are used for the cultivation of photosynthesizing organisms
(plants, algae, bacteria).
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24.  The light was emitted from the surface of the
pipe into the bioreactor.
 The draft tube was constructed as an airtight
tube which consisted of a transparent inner and
outer tube.
 Within the center of the draft tube was a light
introducing optical fiber.
 The light source was a sunlight collector system
which operated automatically by computer
control and the collected light was introduced
into the bioreactor through the optical fibers.
 Introduction of light into the bioreactor will
become an important technique for the
production of specific plant metabolites
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25. REFERENCES
“Fermentation and biochemical engineering handbook”
Principles, Process Design, and Equipment Second Edition by
Henry C. Vogel and Celeste L. Todaro.
“Bioprocess Engineering : Basic Concepts”. 2nd Edition., by
Shuler, M.L. and Kargi, F. Prentice- Hall, 2002.
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