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Summarise and explain what environmental parameters are required for mammalian cells to grow in a bioreactor. (200 words max).

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List the main component parts of a bioreactor and their functions. (200 words max).

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1. Baffle

- Prevents vortex formation

- Helps mitigate excessive shear stress on cells

2. Impeller

- Rotates to create fluid movement and prevent stratification.

- Ensures uniform distribution of nutrients and gases.

- Prevents settling of cells to maintain a homogeneous culture.

Radical: high shear (aerobic bacteria)

Axial: Low shear (animal)

3. Gas supply system

- Supplies oxygen to support aerobic cellular respiration.

- Removes excess carbon dioxide.

- Ensures uniform distribution of gases.

4. Speed control system

- Regulates the speed of impellers for optimal agitation.

- Prevents excessive shear stress on cells.

- Prevent settling of cells.

- Maintains a homogeneous cell suspension

- Fine-tuning of shear forces exerted on cells.

(101 WORDS)

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5. Sparger

- introduces air to provide adequate oxygen to the cell culture.

- uniforms the cell culture by mixing it for the optimal growth and productivity of the cells. spargers create a stream of gas bubbles that rise and agitate the cell culture.

6. Thermal jacket

- ensures and maintain temperature control of the culture.

- uniforms temperature distribution throughout the bioreactor.

7. Agitation system

- mixes homogenously to ensure the uniform distribution of gases, nutrients and other components in the culture.

8. Sampling ports

- allow samples to be collected for analysis without disturbing the entire bioreactor.

(99 words)

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dissolved oxygen is needed for respiration and cell division while CO2 is produced as waste. both factors affect the pH. oxygen level has to be controlled as having a high level of oxygen will have a detrimental effect on the cells as reactive oxygen species will chemically degrade the protein of interest. the optimal range of oxygen is between 30-40%. more than 20% of CO2 is also undesirable, as it will cell growth and protein production. Thus, the optimal range is 5-10%

SKY

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Cellular processes such as:

1) Metabolism

2) Respiration

lead to the formation of lactic acid and CO2 which causes drop in pH.

Drops in pH may disrupt cell growth and lead to cell death as several proteins may be degraded.

A regular culture contains approximately 5-10% of dissolved CO2 which are trapped in nitrogen gas bubbles.

pH is increased back to optimum level (about 7.2 - 7.3) by adding a small amount of base into the medium as high concentrations of the base may also disrupt the growth of the cells.

Several factors need to be understood in order to control pH.

Media Buffering capacity

Cell growth and cell density

sparging and mixing of gases

Build-up and utilization of lactate