Lecture 1

Question 1

Describe applications of biochemical engineering

Answer 1

1. Generation of biomass
   - Industrial production of bakers yeast
   - Animal/human feed
2. Extra-cellular products
   - Products that are excreted by the cell into the environment
   - some are waste products (e.g. alcohols/acids)
   - some are active compounds (e.g. antibiotics/enzyme)
3. Intra-cellular products
   - Products which are retained inside the cells and are extracted from the cells by destroying them
   - E.g. most enzymes, human medical products (insulin)

Question 2

Describe the features of a bioprocessing plant

Answer 2

• Low temperatures
• Near atmospheric pressures
• Low concentrations
• Difficult gas transfer requirements - Again stirring limitations do not help. Mass transfer increased with better convection. Solubility of gas in the medium/broth is facilitated by stronger agitation.
• Difficult heat transfer conditions - Large temperature gradients should be avoided. Microorganisms and enzymes “suffer” (death, denaturation)outside their optimal temperature range. Also stirring limitations do not help re T homogenization
• Complicated feedstock
• Non-Newtonian flow - Flow in tubes. Design of pumps and all equipment becomes more complicated. Special types of stirrers might be needed.
• Requirement for Aseptic operation - If something you don’t want in a bioprocess is contamination by undesirable microorganisms!
• Complicated kinetics and the unpredictability of micro-organisms to changes in conditions lead to difficulties in process and quality control.

Question 3

Why are heat transfer conditions difficult in bioprocessing plants?

Answer 3

Large temperature gradients should be avoided. Microorganisms and enzymes “suffer” (death, denaturation)outside their optimal temperature range. Also stirring limitations do not help re T homogenization

Question 4

Why are gas transfer requirements difficult in bioprocessing plants?

Answer 4

Again stirring limitations do not help. Mass transfer increased with better convection. Solubility of gas in the medium/broth is facilitated by stronger agitation.