Bioprocessing and Fermentation Flashcards

What is the function of a sparger in a bioreactor?

Answer: To introduce small bubbles of air or oxygen into the culture medium

A sparger is a porous device at the bottom of the bioreactor that disperses compressed air or oxygen as fine bubbles to oxygenate the culture.

What is 'downstream processing' in the context of biopharmaceutical manufacturing?

Answer: The series of steps used to isolate and purify the biological product from the fermentation broth

Downstream processing includes all purification steps after fermentation — such as centrifugation, filtration, and chromatography — to obtain a pure final product.

Which culture mode continuously adds fresh nutrients while removing spent media at the same rate to maintain a constant volume?

Answer: Continuous (chemostat) culture

In a chemostat, fresh medium is added at a constant rate equal to the outflow rate, maintaining steady-state cell density and nutrient concentration.

What does pH control in a bioreactor typically involve?

Answer: Automated addition of acid or base in response to pH probe readings to maintain the setpoint

Bioreactors use feedback control loops where pH probes trigger addition of acid (e.g., HCl) or base (e.g., NaOH) to maintain the optimal pH setpoint.

What is 'scale-up' in bioprocessing?

Answer: Increasing the production volume from small laboratory bioreactors to large industrial-scale fermenters

Scale-up involves transitioning processes from bench-scale (liters) to pilot scale and then to manufacturing scale (thousands of liters) while maintaining product quality.

What is the role of antifoam agents in fermentation?

Answer: To prevent excessive foam formation that can block air filters and reduce oxygen transfer

Antifoam agents (e.g., silicone-based compounds) reduce surface tension to collapse foam bubbles that can clog exhaust filters and reduce oxygen transfer.