F10 Bacteria for Biofuels

Question 1

What are cyanobacteria?

Answer 1

Cyanobacteria are photosynthetic bacteria.

They use CO₂ as (fully oxidised) carbon source

They use light energy to reduce it to hydrocarbons (add e^- and H⁺)

Question 2

What do chemical engineers have to do with cell metabolism?

Answer 2

1. Microbes have been exploited for ‘biotech’ for centuries
2. Yeast as an example for a cell factory
3. Cell factories convert substrate(s) to products efficiently
4. Mass balances allow us to predict product yields (FBA)
5. Engineering of cell factories for biofuels

Question 3

Cell factories convert substrates to products. What feedstock can we start with and what products can be made (include a description of middle steps)

Answer 3

Question 4

What is the most common cell factory (what does it use and what does it produce)?

Answer 4

The most common cell factory: yeast to make ethanol

• Ethanol fermentation has been used 1000s of years → beer etc.
• Currently approx. 5.2 billion L/year produced in Europe

Area of switchgrass (rödhirs) is needed to supply approx. 100 million L EtOH/year

Question 5

How does metabolism work, energetically?

Answer 5

Question 6

The feasibility and direction of all reactions are determined by the change in Gibbs free energy, describe the reaction and if delta G is -/+ if the reaction is spontaneous.

Answer 6

Question 7

Simple schematic picture of how NAD+ is regenerated from NADH by ethanol formation

Answer 7

Question 8

Clostridia’s fermentation is complex! Clostridia recycles NADH by making several fermentation products. What are they and how many NADH do they produce?

Answer 8

Question 9

Why and how do we do basic modelling of cellular metabolism?

Answer 9

Question 10

What is the procedure for Flux Balance Analysis (FBA)?

Answer 10

Question 11

What is step 1 in Flux balance analysis (FBA)?

Answer 11

Question 12

What is step 2 in Flux balance analysis (FBA)? Example

Answer 12

Question 13

What is step 3 in Flux balance analysis (FBA)?

Answer 13

Question 14

What are the applications of Flux Balance Analysis (FBA)?

Answer 14

Question 15

How does optimisation work?

Answer 15

Question 16

What could cause Flux Balance Analysis (FBA) to be wrong?

Answer 16

Question 17

Four steps (circular) in engineering biofuels

Answer 17

Question 18

Summary of Metabolic engineering of bacteria for Biofuells

Answer 18

Question 19

Yeast is a model sugar consuming unicellular fungus. What happens if there is O₂ or no O₂? And how many ATP are formed in each route?

Answer 19