Question

What does the term 'fed' in fed-batch culture refer to?

Hint:

Fed-batch culture is widely used in industry for producing recombinant proteins (like human insulin) because it prevents the high substrate concentrations that can trigger metabolic overflow and toxic acetic acid production.

Answer 1

Step 1: Concept
A fed-batch culture is an advancement over standard batch fermentation, designed to extend the high-growth phase of the culture.

Step 2: Defining 'Fed'
The term "fed" refers to the periodic or continuous addition of fresh nutrient medium (such as concentrated substrate, carbon feed, or precursor molecules) to the bioreactor during the run, without removing any of the culture liquid.

Step 3: Operational Significance
Feeding keeps key nutrient concentrations at optimal levels, avoiding the sudden nutrient depletion seen in standard batch systems. Because no liquid is removed, the fermenter volume increases over the course of the run. Final Answer: The term "fed" refers to the controlled addition of fresh nutrient medium to the bioreactor during fermentation, without withdrawing any culture liquid, keeping the cells in their active growth phase.