A 3.0 L batch bioreactor is used to grow E. coli bacteria, which have an initial concentration of 12.5 g cells/L. The growth medium contains two carbon sources, which causes diauxic growth, with each carbon source limiting cell growth. Sufficient supplies of oxygen, ammonium nitrate (NH4NO3) as a nitrogen source and all other macro and micronutrients are available. The bacteria prefer to grow on glucose (C6H12O6, supplied at 80 g/L), so it is consumed first, followed by glycerol (C3H8O3, supplied at 68 g/L). Since the E. coli were already growing on glucose, the lag time associated with glucose consumption is only 10 minutes. The lag time associated with glycerol consumption is 35 minutes. Further information: The chemical formula for E. coli in this bioreactor is CH1.666N0.20O0.57. The specific growth rate on glucose is 0.41 h-1 , and on glycerol is 0.32 h-1 . The yield of cells on glucose is 0.48 g cells/g glucose, and yield on glycerol is 0.39 g cells/g glycerol. You may assume that the length of time that the cells are in deceleration phase is negligible. A. How much total oxygen (O2) is consumed during the growth phase on glucose (g O2)? B. How much total oxygen (O2) is consumed during growth on glycerol (g O2)? C. At what minimum rate must oxygen be supplied to the reactor so it does not limit the growth rate (g O2/h)? (assume the oxygen supplied is fully available to the cells and we don’t have to consider mass transfer or OTR)
A 3.0 L batch bioreactor is used to grow E. coli bacteria, which have an initial concentration of 12.5 g cells/L. The growth medium contains two carbon sources, which causes diauxic growth, with each carbon source limiting cell growth. Sufficient supplies of oxygen, ammonium nitrate (NH4NO3) as a nitrogen source and all other macro and micronutrients are available. The bacteria prefer to grow on glucose (C6H12O6, supplied at 80 g/L), so it is consumed first, followed by glycerol (C3H8O3, supplied at 68 g/L). Since the E. coli were already growing on glucose, the lag time associated with glucose consumption is only 10 minutes. The lag time associated with glycerol consumption is 35 minutes. Further information: The chemical formula for E. coli in this bioreactor is CH1.666N0.20O0.57. The specific growth rate on glucose is 0.41 h-1 , and on glycerol is 0.32 h-1 . The yield of cells on glucose is 0.48 g cells/g glucose, and yield on glycerol is 0.39 g cells/g glycerol. You may assume that the length of time that the cells are in deceleration phase is negligible.
A. How much total oxygen (O2) is consumed during the growth phase on glucose (g O2)?
B. How much total oxygen (O2) is consumed during growth on glycerol (g O2)?
C. At what minimum rate must oxygen be supplied to the reactor so it does not limit the growth rate (g O2/h)? (assume the oxygen supplied is fully available to the cells and we don’t have to consider mass transfer or OTR)
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