Lecture 6

Question 1

Define the assumptions made for the stoichiometry of growth

Answer 1

• Cell growth obeys conservation law of matter
• All atoms consumed during growth are incorporated into new cells(biomass) or excreted as products
• Products either directly or indirectly liked to metabolism(dependent on reaction pathway)

Question 2

Define metabolic product

Answer 2

Substance different from cell material(biomass) released to medium

Question 3

What is the typical nomenclature for stoichiometry of growth?

Answer 3

Substance being consumed (S or s), biomass/cells/micro-organisms(X or x), Products (P or p)
=> upper case letters for mass, lower case letters for conc. (i.e. X=mass of cell, x=conc. of cell)

Question 4

Describe the simplifications

Answer 4

• From usual multiple substrates consumed during cell growth, one is rate/growth limiting
• Growth limiting substrate might not be stoichiometrically limiting substrate (often ignored)
• Macroscopic analysis assumes growth limiting substrate = stoichiometrically limiting substrate

Question 5

What is the average MW for biomass?

Answer 5

24.6

Question 6

What is the stiochemtry for aerobic cell growth?

Answer 6

substrate(growth limiting) + oxygen + nitrogen source —> biomass +CO2 +H2O

Question 7

What is the respiratory quotient (RQ)?

Answer 7

RQ = moles CO2 produced / moles O2 consumed = d/a

Question 8

What is biomass yield? (Y_XS)

Answer 8

Y_XS = grams of cell produced/ grams of substrate consumed = (c x (MW biomass))/ (MW substrate)

Question 9

What is product yield coefficient? (Y_PS)

Answer 9

Y_PS = grams of product formed/ grams of substrate consumed = ( f x (MW product))/ (MW substrate)