BACE Bioprocessing and Fermentation 1 — Questions and Answers
Question 1: What is a bioreactor primarily used for in biotechnology?
- To provide a controlled environment for growing microorganisms or cells to produce biological products (Correct answer)
- To store biological samples at low temperatures
- To separate proteins by molecular weight
- To amplify DNA sequences
Correct answer: To provide a controlled environment for growing microorganisms or cells to produce biological products
A bioreactor is a vessel designed to maintain optimal conditions (pH, temperature, oxygen, nutrients) for biological processes such as fermentation or cell culture.
Question 2: What does the term 'sterile technique' mean in the context of bioprocessing?
- Using methods that prevent contamination of cultures by unwanted microorganisms (Correct answer)
- Using high-temperature processes to kill all biological agents
- Filtering all media through a 0.45-micron filter
- Adding antibiotics to all growth media
Correct answer: Using methods that prevent contamination of cultures by unwanted microorganisms
Sterile technique encompasses all practices used to prevent introduction of contaminants into biological cultures during bioprocessing operations.
Question 3: Which parameter is most critical to monitor during aerobic fermentation in a bioreactor?
- Dissolved oxygen (DO) concentration (Correct answer)
- Light intensity inside the vessel
- Atmospheric pressure outside the bioreactor
- Color of the media
Correct answer: Dissolved oxygen (DO) concentration
Dissolved oxygen is critical because aerobic organisms require adequate oxygen for metabolism, and DO depletion can halt growth or shift metabolism.
Question 4: What is the purpose of an autoclave in bioprocessing?
- To sterilize media, equipment, and waste using steam under pressure (Correct answer)
- To centrifuge large volumes of culture broth
- To filter sterile air into the bioreactor
- To measure pH of growth media
Correct answer: To sterilize media, equipment, and waste using steam under pressure
An autoclave uses saturated steam at 121°C and 15 psi for typically 15–20 minutes to kill all microorganisms including heat-resistant spores.
Question 5: In batch fermentation, when does the 'stationary phase' occur?
- When nutrient depletion causes the growth rate to equal the death rate, with no net change in cell number (Correct answer)
- When cells are first inoculated into fresh media
- When cells are growing at their maximum rate
- When the bioreactor is being cleaned between runs
Correct answer: When nutrient depletion causes the growth rate to equal the death rate, with no net change in cell number
The stationary phase occurs after exponential growth when nutrients become limiting and the rate of cell growth equals the rate of cell death.
Question 6: What is 'upstream processing' in bioprocessing?
- All steps involved in growing and harvesting cells or microorganisms, including media preparation and fermentation (Correct answer)
- The purification of the final biological product
- Quality control testing of the finished product
- Formulation and packaging of the product
Correct answer: All steps involved in growing and harvesting cells or microorganisms, including media preparation and fermentation
Upstream processing encompasses all steps before product recovery, including strain selection, media preparation, inoculum development, and bioreactor operation.
BACE Bioprocessing and Fermentation 1
What is a bioreactor primarily used for in biotechnology?