Biochem Week 8 Flashcards
What is fermentation to a biochemist?
Anaerobic process that generates energy by the breakdown of organic compounds.
What is fermentation in industry?
Any aerobic process that produces microorganisms (biomass) as the end product.
Transformation of a compound by microbial cells.
What are biochemical engineers responsible for in fermentation?
To ensure that microorganisms can be grown in large quantities under the conditions that give optimal product yield.
Definition of a bioreactor
Aerobic and anaerobic microorganisms are cultured under controlled conditions in a large chamber. This is a bioreactor or fermenter.
Processes of fermentation.
- Batch Fermentation
- Fed-Batch Fermentation
- Continuous Fermentation
The mechanism of batch fermentation
The sterile growth medium is inoculated with the appropriate microorganisms and the fermentation proceeds without the addition of fresh growth medium
The properties within batch fermentation
The composition of culture medium, concentration of microorganisms, the internal chemical composition of microorganisms and amount of metabolite all change during fermentation
All phases of bacterial growth cycle are observed.
The mechanism of fed-batch fermentation
Fresh growth medium is added continuously during fermentation and no growth medium is removed until the end of the process.
Which phases does the continuous addition of medium affect?
It prolongs the stationary and log phases, thereby increasing the biomass and the amount of metabolites.
How does fed-batch compare to batch fermentation?
A fed-batch fermentation strategy can increase the yield from 25% to more than 1000%.
How to control the addition of feed in fed-batch fermentation?
Fed-batch fermentation is a system in which nutrient is added when the concentration falls below some set point. The best way to control the addition is to monitor the concentration of the nutrient itself in the fermenter or reactor vessel so know exactly how much needs to be added.
When is the fed-batch strategy used?
It is used in bio-industrial processes to reach a high cell density in the bioreactor.
Is the feed solution concentrated or dilute?
Mostly the feed solution is highly concentrated to avoid dilution of bioreactor.
The primary benefit of the controlled addition of a nutrient
It directly affects the growth rate of the culture and helps to avoid the overflow metabolism.
Why is the nutrient is added in several doses?
To ensure that there is not too much nutrient present in the fermenter at any time. If too much of a nutrient is present, it may inhibit cell growth. By adding a little at a time, the reaction can proceed at a high rate of production without getting overloaded.
