Leanne Kuwahara-Week 14/15

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Purpose

  • To model temperature dependence of a chemostat experiment at 15, 20, and 25C.
  • To investigate the glucose efficiency and waster "constant" for the glucose and ammonium-limited cultures.

Protocol

  1. Temperature dependence modeling:
    • Arrhenius equations used:
      • (1) k = Ae^(-Ea/RT)
      • (2) Ea = (Rln(k1/k2))/(1/T1-1/T2)
        • k = rate (r)
          • k1 = r cold (0.08)
          • k2 = r hot (0.46)
        • A = frequency factor
          • related to molecular collision
          • dependent on reaction
        • Ea = energy of activation
        • R = gas constant (8.3145J/mol K)
        • T = temperature (K)
          • T1 = T cold (12C)
          • T2 = T hot (30C)
  2. Determined Ea using equation 2 and then plugged into equation 1 to find A
  3. Used equation 1 with T = 15, 20, 25C to determine r at these temperatures
  4. Modeled temperature dependence in MATLAB
    • Added three conditions/cases (T = 15, 20, 25C) to the TaiParams sheet
    • Used C-limited conditions determined from paper for feed concentrations of glucose and ammonium, residual concentrations of glucose and ammonium, and Y(glu/x)
  1. Efficiency/Waste Modeling:
    • Yeast produce more waste (EtOH and CO2) when glucose is plentiful
    • Waste is relatively equal between temperatures
      • Prefer fermentation vs. respiration
    • Compared efficiency of glucose conversion to biomass in C-limited cultures vs. N-limited cultures
  2. Used (y,E) of C-limited and N-limited at 12 or 30C
  3. Solved for m using y-y = m(x-x)
  4. Solved for b using y = mx+b
  5. Solved for efficiency using my+b, where y is the residual glucose

Results

Part 1. Temperature Dependence

12C.png 15C.png 20C.png 25C.png 30C.png

  • Residual glucose decreases as temperature increases
  • All plots were generated under the assumption of the limiting nutrient being glucose
    • Residual concentrations of ammonium and glucose were adjusted to be within the range provided by the Tai et al. (2007) paper to best fit the model

Part 2. Efficiency/Waste Modeling

Waste efficiency comparison.png

  • top: Original model where E = 1/Y
    • E(12C, C-lim) = 14.2857
    • E(12C, N-lim) = 20.0000
    • E(30C, C-lim) = 14.2857
    • E(30C, N-lim) = 25.0000
  • bottom: Effciency modified, where E = my + b
    • 12C: m = 0.364532365; y = residual glucose (g) b = 14.08867026
    • 30C: m = 0.701234358; y = residual glucose (g) b = 14.24776322
    • E(12C, C-lim) = 14.2741
    • E(12C, N-lim) = 20.0089
    • E(30C, C-lim) = 14.2879
    • E(30C, N-lim) = 24.9987

Data and Files

Acknowledgements

Except for what is noted above, this individual journal entry was completed by me and not copied from another source.

References

Links