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Monday, November 26, 2007

Day One - Experiment One

11:08:00 AM

Day 1

Experiment 1: Familiarization with the Bioreactor and its Operation

Objectives

1. To familiarize students with the parts and components of microbial and mammalian bioreactors

2. To introduce the basic operation procedure of a bioreactor

A photo of Our Savior: the beloved bioreactor

Our Savior has many different important parts that serve different functions. Long live the bioreactor!

*click on the photo to see the enlarged version

1. Motor - to drive the motion of the impeller by supplying electrical power

2. Impeller - to mix the media such that cells are prevented from settling at the bottom of the fermenter, and to distribute the bubbles evenly throughout the broth

3. Sparger - to supply sufficient oxygen and other essential gases required by sparging in air

4. Baffles - to ensure even gas and nutrient distribution, such that there is good mixing

5. Inlet air filter - to sterilize the inlet air stream and remove any possible contaminants using a 0.22nm filter

6. Exhaust air inlet - to sterilize the outlet air stream by also using filter

7. Rotameter - to measure the gas flow rate

8. Pressure gauge - to measure air pressure in the fermenter

9. Temperature probe - to measure the temperature of the media

10. Cooling jacket - to cool or heat the water

11. pH probe - to measure pH of media

12. Dissolved oxygen probe - to measure the amount of dissolved oxygen in the broth and ensure cells have obtained sufficient oxygen and other essential gas components

13. Level probe - to measure the level of the liquid in the bioreactor

14. Foam probe - to detect increasing levels of foam that may form during the run, such that the appropriate action can be taken

15. Acid / Base - to neutralise the changes incurred during the fermentation process

16. Antifoam - to prevent build-up of foam and break the surface tension to break bubbles that may coagulate during the run

17. Sampling tubes - for sampling of cultures at consistent intervals in order to monitor the growth of cells and their constituent products

18. Control panel - to settle parameters

Further questions...

1. State the differences you observe between a microbial bioreactor and a mammalian cell bioreactor.

Microbes (such as bacteria) are mostly robust and able to resist shear damage. Hence, high-shearing radial impeller systems and high agitation rates can be used as part of the properties of the bioreactor. This provide high mass transfer capability and allow rapid metabolising with high-cell density microbial cell cultivations to be supported. Rushton turbines can be used to scale-up microbial cells.

However, mammalian cells are must more gentle and more susceptible to shear force thus gentle handling is required. Stirred tank bioreactors with marine-type impellers can be used to scale-up mammalian cells.

2. Describe the typical activities that are performed on each stage in the fermentation process.

Back to Homepage

Day 1, Experiment 2: Equipment, media and seed culture preparation

Day 2: Inoculation, fermentation and monitoring

Day 3: Sampling and monitoring of cell growth

Day 4: Harvesting the cells

Day 5: Isolation and purification of product