6.4.11 Batch and Continuous Fermentation Flashcards
What are the two methods used to culture microorganisms?
Microorganisms can be grown under controlled conditions in larger fermenters
The product of fermentation is either the microorganisms itself e.g. mycoprotein, or a product produced by the microorganism e.g. insulin
There are two main methods used to culture microorganisms by fermentation:
Batch fermentation
Microorganisms are grown in batches in the fermentation vessel
Once the culture cycle is complete, the product is removed, the fermenter is cleaned and a new batch of microorganisms is grown
This is known as a closed culture
Continuous fermentation
Microorganisms are continually grown and the products harvested
Nutrients are added and waste is removed throughout the culturing process
How can optimum conditions be maintained in the fermenter?
In order to maximise growth and productivity of the microorganisms, the fermenter must be carefully monitored and controlled to ensure conditions are optimum
PH- pH is monitored by probes and acids or alkalis added to provide optimum pH for enzyme activity. This means rates of reaction are maximised and consequently so is growth and productivity of the microorganisms
Temperature- Optimum temperatures are maintained using a water jacket. This facilitates maximum enzyme activity and therefore maximum yield
Oxygen availability- Sterile air is pumped in to provide optimum oxygen to maximise respiration and therefore maximise yield
Nutrient supply- Nutrients are added and circulated to ensure microorganisms can access the nutrients required for maximum yield
Agitation- Paddles are used to ensure even distribution of temperature, nutrients, pH and oxygen throughout the fermenter
Contamination- Contamination of the culture can lead to interspecific competition for nutrients, oxygen and space, this will reduce product yield.
Fermenters must be steam cleaned between cultures to prevent contamination
Waste removal- Waste products produced by the microorganisms can have a negative effect on the growth and productivity of the microorganisms. Waste products are constantly removed to prevent these toxic effects
