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Unformatted text preview: BME 339/CHE 339/BIO 335 Fall 2011 Homework #1 Assigned: September 1, 2011 Due: Thursday, September 8, 2011 1) A simple, batch fermentation of an aerobic bacterium, growing on maltose gave the following results: Time (h) Cell Concentration (g/l) Maltose Concentration (g/l) 0 0.2 9.23 2 0.211
10 1.77 6.8 12 3.2 4.6 14 5.6 0.92 16 6.15 0.077 18 6.2 0.0 a. Calculate the maximum growth rate (µmax). b. Calculate the apparent growth yield.(Y X/S) c. Calculate the mass doubling time. (tD) d. Calculate the saturation constant (KS) e. Calculate the growth rate at t = 10 h 2) A yeast (CH1.66N0.13O0.40) is growing aerobically on arabinose (C5H10O5) and ammonium hydroxide (NH4OH) with a respiratory quotient of 1.4. a. Determine the yield coefficient, YX/S, for this system in grams biomass/gram substrate. b. What is the maximum biomass concentration that can be achieved in batch growth for this system if the initial substrate concentration is 10 g/L and the initial biomass concentration is 0.5 g/L. 3) Consider the cultivation of bacteria with empirical biomass formula CH1.6O0.55N0.20 (MWB = 25.2 g/mole). The bioreactor is a closed, rigid vessel into which liquid medium containing 10 mmol glucose (C6H12O6) and an excess of ammonium sulfate is added. The headspace contained humidified air initially. After some time, during which a net growth of 0.3 g dry cell weight was achieved, the headspace gas was analyzed. After accounting for the appropriate liquid concentration of O2 in equilibrium with the headspace, it was found that a total of 15 mmol O2 was consumed. This organism secretes no appreciable amounts of product under these conditions. a. Estimate the yield coefficient of substrate, YX/S (g DCW/mole glucose) and the final amount of glucose in the medium (mmol). b. Estimate how much CO2 was produced (mmol). 4) Your boss asked you to determine the µmax and Ks values for the organism Longhornious pestis which was recently discovered at the Royal Memorial stadium. You have in your disposal shake flasks, growth media (you wish to grow the bacteria with glucose as the limiting nutrient) and standard microbiological equipment (but no continuous stirred tank fermenter) Describe what experiments you would need to do, the data you will have to obtain and how you will plot the data to calculate the parameters you need. ...
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- Spring '11