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By: Mdm. Noor Amirah Abdul Halim BIOREACTION AND BIOREACTOR

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WHAT IS BIOREACTOR? A special reactor that sustains and supports life for cells and tissue cultures. Used in industrial processes to produce pharmaceuticals, vaccines, or antibodies Bioreactors are commonly employed in the food and fermentation industries, in waste treatment, and in some biomedical operations - the heart of any industrial fermentation process. The advantages are mild reaction conditions, high yields and stereospecific compounds. Bioreactors supply a homogeneous (same throughout) environment by constantly stirring the contents. Bioreactors give the cells a controlled environment by ensuring the same temperature, pH, and oxygen levels. A special reactor that sustains and supports life for cells and tissue cultures. Used in industrial processes to produce pharmaceuticals, vaccines, or antibodies Bioreactors are commonly employed in the food and fermentation industries, in waste treatment, and in some biomedical operations - the heart of any industrial fermentation process. The advantages are mild reaction conditions, high yields and stereospecific compounds. Bioreactors supply a homogeneous (same throughout) environment by constantly stirring the contents. Bioreactors give the cells a controlled environment by ensuring the same temperature, pH, and oxygen levels.

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BIOREACTOR AND ITS PARTS

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THE CELL

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A cell uses its nutrients to produce energy and more cells. The cell consists of a cell wall and an outer membrane that encloses cytoplasm containing a nuclear region and ribosomes. The cell wall protects the cell from external influences. The cell membrane provides for selective transport of materials into and out of the cell THE CELL

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CELL GROWTH The growth of an aerobic organism follows the equation; SUBSTRATE

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STAGES OF CELL GROWTH

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RATE LAW FOR BIOREACTOR The most commonly used expression is the Monod equation for the exponential growth The specific growth rate can be expressed as; Thus,

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For most of the bacteria, Ks is small ( ) Thus, it can be neglected to give; Growth rate, r g depends on the nutrient concentration (C s ) RATE LAW FOR BIOREACTOR

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INHIBITION OF THE GROWTH RATE (r g ) In many systems, product inhibits the growth rate. Wine production is an example where fermentation of glucose to produce ethanol is inhibited by the product ethanol (ethanol kills the yeast)

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TESSIER AND MOSER EQUATION Tessier & Moser equations are another equation used to describe the cell growth rate. They fit the experimental data better. and k are empirical constants TESSIER MOSER

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CELL DEATH RATE (r d ) The cell death is a result of; - harsh environments - depletion of nutrients - presence of toxic substance The rate law for cell death is given by;

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EFFECT OF TEMPERATURE The cell growth at temperature =T

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STOICHIOMETRY FOR BIOREACTIONS

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RATE OF PRODUCT FORMATION (r p ) Product formation can take place during different phases of the cell growth cycle. When product formation only occurs during the exponential growth phase, the rate of product formation is:

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Rate of product formation (r p ) during growth phase

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Rate of product formation (r p ) during stationary phase

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MASS BALANCES

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Batch operation Cell

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Substrate Growth phase stationary phase

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Product

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Chemostat

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DESIGN EQUATION CSTR (chemostat) The case where the volumetric flow rates in and out are the same and no live cells enter the chemostat Dilution rate Dilution rate is a parameter used in bioreactor. It is reciprocal of space time

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CSTR Mass Balance Using Monod Eqn;the growth rate,r g

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For steady state operation; Mass flowrate of cells out of the system, Fc Divide by Cc V, Neglect death rate The specific growth rate of the cell can be controlled by the dilution rate,D The specific growth rate of the cell can be controlled by the dilution rate,D

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From Monod Equation, If a single nutrient is limiting, - cell growth is the only process to substrate consumption. -cell maintenance is neglected. Then,

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WASH OUT To learn the effect of increasing the dilution rate; Assume; the dilution rate at which wash-out will occur is:

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D for the maximum cell production: {Cell production per unit volume is the mass flow rate of cells out of the reactor} :

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Cell growth takes place in bioreactors called chemostat. A substrate such as glucose is used to grow cells and produce a product which is CO2. Glucose cell More cells + CO 2 By assuming 1 mole of glucose (180g/dm3) reacts, to produce 0.909 mol/dm3 of cells (MW: 91.34 g/mol) and 1.47 mol/dm3 of CO2 Calculate: (a) The yield coefficient Y C/S (b) The yield coefficient, Y c/p (c) The rate of cell growth r g ( k = 1.3 h-1 and max = 2.2 x 10-5 s-1) (d) The rate of product formation, r p during the exponential growth (e) The rate of substrate consumption (-r s ) during the exponential growth (m = 0.05 h-1) Exercise