07 Bioprocessing and Bioreactors Free Online FlashCards

What is a bioreactor?

A controlled vessel or system for growing cells or microorganisms and often producing a desired product.

What does an impeller do in a stirred-tank bioreactor?

It agitates the culture to mix nutrients, distribute heat, and help disperse gas. Its type and speed also affect forces experienced by cells.

What is the function of a sparger?

It introduces air or other gases as bubbles. Oxygen transfer is especially important in aerobic cultures.

How do baffles improve stirred-tank operation?

Baffles reduce swirling and improve mixing in many stirred tanks.

What is a seed train?

A seed train is a sequence of progressively larger cultures used to expand cells before inoculation into the production bioreactor.

How is a batch culture supplied with nutrients?

The main nutrients are supplied at the start, and the culture proceeds until harvest.

What distinguishes fed-batch cultivation?

Additional nutrients are fed during cultivation; the feed rate can help manage growth and product formation.

How does continuous cultivation operate?

Fresh medium enters while culture broth is removed, allowing ongoing operation under defined conditions.

Which operating variables are commonly monitored in a bioreactor?

Common measurements include temperature, pH, dissolved oxygen, agitation, gas flow, pressure, foam, and liquid level.

How can a control system respond to low dissolved oxygen?

A control system may increase agitation or airflow, or enrich inlet gas with oxygen, subject to process limits.

How can bioreactor pH be adjusted?

pH may be adjusted through controlled addition of acid, base, or gas.

Why does enlarging a vessel alone not guarantee successful scale-up?

Larger vessels can mix more slowly and develop gradients in oxygen, nutrients, pH, or temperature, so simply enlarging a vessel does not ensure equivalent performance.