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TLS Online TPP Program

#Question id: 14244

Ethanol is produced by anaerobic fermentation of glucose by Saccharomyces cerevisiae. For the particular strain of S. cerevisiae employed, the maintenance coefficient is 0.18 kg kg- 1 h- 1, Yxs is 0.11 kg kg-1, YPX is 3.9 kg kg-1 and µmax is 0.4 h-1.  It is decided to investigate the possibility of using Zymomonas mobilis bacteria instead of yeast for making ethanol. Z. mobilis is known to produce ethanol under anaerobic conditions using a different metabolic pathway to that employed by yeast. Typical values of Yxs are lower than for yeast at about 0.06 kg kg-1; on the other hand, the maintenance coefficient is higher at 2.2 kg kg -1 h -1. Ypx for Z. mobilis is 7.7 kg kg-l; µmax is 0.3 h- 1.  From stoichiometry, what is the maximum theoretical yield of ethanol from glucose                 

#Section 5: Bioprocess Engineering and Process Biotechnology
  1. 0.51gg-1       
  2. 0.71gg-1    
  3. 0.61gg-1
  4. 0.91gg-1   
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TLS Online TPP Program

#Question id: 14276

#Section 5: Bioprocess Engineering and Process Biotechnology

Nicotiana tabacum cells are cultured to high density for production of polysaccharide gum. The reactor used is a stirred tank, containing initially 100 litres medium. The maximum specific growth rate of the culture is 0.18 d-1 and the yield of biomass from substrate is 0.5 g g-l. The concentration of growth-limiting substrate in the medium is 3% (w/v). The reactor is inoculated with 1.5 g l- 1 cells and operated in batch until the substrate is virtually exhausted; medium flow is then started at a rate of 4 l d-1. Fed-batch operation occurs under quasi-steady-state condition. The fermenter is available 275 d per year with a downtime between runs of 24 h. How much plant cell biomass is produced annually? ___________________

TLS Online TPP Program

#Question id: 14277

#Section 5: Bioprocess Engineering and Process Biotechnology

Lactobacillus casei is propagated under essentially anaerobic conditions to provide a starter culture for manufacture of Swiss cheese. The culture produces lactic acid as a by-product of energy metabolism. The system has the following characteristics:

                                                                 

 

A stirred fermenter is operated in fed-batch mode at quasisteady state with a feed flow rate of 4 m3 h-1 and feed substrate concentration of 80 kg m-3. After 6 h, the liquid volume is 40 m3. What mass of cells is produced after 6 h fed-batch operation?

                               __________________
TLS Online TPP Program

#Question id: 14278

#Section 5: Bioprocess Engineering and Process Biotechnology

Stirrer has a power number (Np) 10. If the stirrer speed (N) is 1s^-1, its diameter D=1m and the density of the medium is 1000 kg/m^3, the ungassed power input (P) in watts is 
TLS Online TPP Program

#Question id: 14279

#Section 5: Bioprocess Engineering and Process Biotechnology

Growth yield of mDicrobes is defined as
TLS Online TPP Program

#Question id: 14280

#Section 5: Bioprocess Engineering and Process Biotechnology

In microbial cultivation, the expression for product synthesis
TLS Online TPP Program

#Question id: 14281

#Section 5: Bioprocess Engineering and Process Biotechnology

cells are grown in a CSTR a steady state at two dilution rates 0.1 h^-1 and 0.5h^-1 and the steady state concentrations are as follows: 


if the inlet substrate concentration is 20 g/I, the cells follow monod growth kinetics and product formation kinetics is modelled as a both growth associated and non growth associated kinetics given by the equation then answer the following questions, the best estimate of maximum specific growth rate is: