Problems On Cell Kinetics.pdf

ChE 514A: Biochemical Engineering

Cell Kinetics

GSDV

PROBLEMS ON CELL KINETICS: 1. [Ex. 11-1/P.561, Bioprocess Engineering: Kinetics, Biosystems, Sustainability, and Reactor Design by Shijie Liu] A strain of mold was grown in a batch culture on glucose and the following data were obtained as shown in the table. Time, h Cell concentration, g/L Glucose concentration, g/L 0 1.0 50.0 10 1.5 48.5 18 2.9 45.2 25 5.5 38.8 33 11.4 24.0 37 16.3 11.8 40 19.2 4.5 44 20.9 0.3 Do the following: a. Calculate the maximum net specific growth rate. b. Calculate the apparent growth yield. c. What maximum cell concentration could one expect if 150 g/L of glucose were used with the same size inoculum? d. How many generations of cells are there in the culture for part (c)? 2. [Problem 11.1/p. 601, Bioprocess Engineering: Kinetics, Biosystems, Sustainability, and Reactor Design by Shijie Liu] A simple, batch fermentation of an aerobic bacterium growing on methanol gave the results shown on the table. Time, h X, g/L S, g/L Time, h X, g/L S, g/L 0 0.20 9.23 12 3.20 4.60 2 0.21 9.21 14 5.60 0.92 4 0.31 9.07 16 6.15 0.08 8 0.98 8.03 18 6.20 0 10 1.77 6.80 Calculate: a. Maximum growth rate, µmax b. Yield on substrate, YX/S c. Mass doubling time, td d. Saturation constant, KS e. Specific growth rate (µnet) at t = 10 h 3. [Ex 11.8, Bioprocess Engineering Principles by Doran] A mouse-mouse hybridoma cell line is used to produce monoclonal antibody. Growth in batch culture is monitored with the following results. Time (d) Cell concentration (cells/mL x10-6) 0.0 0.45 0.2 0.52 0.5 0.65 1.0 0.81 1.5 1.22 2.0 1.77 2.5 2.13 1

ChE 514A: Biochemical Engineering

Cell Kinetics

GSDV

3.0 3.55 3.5 4.02 4.0 3.77 4.5 2.20 a. Determine the specific growth rate during the growth phase. b. What is the culture doubling time? 4. Escherichia coli grows with a doubling time of 0.5 h in the exponential growth phase. (a) What is the value of the specific growth rate? (b) How much time would be required to grow the cell culture from 0.1 kg dry cell/m3 to 10 kg dry cell/m3? 5. E. coli grows from 0.10 kg dry cell/m3 to 0.50 kg dry cell/m3 in 1 h. (a) Assuming exponential growth during this period, evaluate the specific growth rate. (b) Evaluate the doubling time during the exponential growth phase. (c) How much time would be required to grow from 0.10 kg dry cell/m3to 1.0 kg dry cell/m3? You may assume the exponential growth during this period. 6. Escherichia coli is being used for production of recombinant porcine growth hormone. The bacteria are grown aerobically in batch culture with glucose as growth-limiting substrate. Cell and substrate concentrations are measured as a function of culture time; the results are listed below. Time Cell concentration, X Substrate Concentration h Kg/m3 Kg/m3 0.0 0.20 25.0 0.33 0.21 24.8 0.5 0.22 24.8 0.75 0.32 24.6 1.0 0.47 24.3 1.5 1.00 23.3 2.0 2.10 20.7 2.5 4.42 15.7 2.8 6.9 10.2 3.0 9.4 5.2 3.1 10.9 1.65 3.2 11.6 0.2 3.5 11.7 0.0 3.7 11.6 0.0 (a) Plot u as a function of time. (b) What is the value of umax ? (C) What is the observed biomass yield from substrate? Is Y X/S constant?

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