2NH3#Question id: 14329
#SCPH05 I Biotechnology
During exponential phase in batch culture, the growth rate of a culture is proportional to the concentration of cells present. When Streptococcus lactis bacteria are cultured in milk, the concentration of cells doubles in45 min. If this rate of growth is maintained for 12 h, what is the final concentration of cells relative to the inoculum level?
#Question id: 14330
#SCPH05 I Biotechnology
A radioactive isotope decays at a rate proportional to the
amount of isotope present. If the concentration of isotope is C (mg l-I),
its rate of decay is:
A solution of the isotope 32p is used to
radioactively label DNA for hybridisation studies. The half-life of 32p
is 14.3 days. According to institutional safety requirements, the solution
cannot be discarded until the activity is 1% its present value. How long will
this take?____________________
#Question id: 14331
#SCPH05 I Biotechnology
To ensure turbulent conditions and minimum mixing time during agitation with a turbine impeller, the Reynolds number must be at least 104. A stirred laboratory-scale fermenter with a turbine impeller 5 cm in diameter is operated at 800 rpm. If the density of broth being stirred is close to that of water, what is the upper limit for viscosity of the suspension if adequate mixing is to be maintained?
#Question id: 14332
#SCPH05 I Biotechnology
To ensure turbulent conditions and minimum mixing time during agitation with a turbine impeller, the Reynolds number must be at least 104. A stirred laboratory-scale fermenter with a turbine impeller 5 cm in diameter is operated at 800 rpm. If the density of broth being stirred is close to that of water. The mixing system is scaled up so the tank and impeller are 15 times the diameter of the laboratory equipment. The stirrer in the large vessel is operated so that the stirrer tip speed (tip speed = π N i D i) is the same as in the laboratory apparatus. How does scale-up affect the maximum viscosity.
#Question id: 14333
#SCPH05 I Biotechnology
A cylindrical bioreactor of diameter 3 m has four baffles. A Rushton turbine mounted in the reactor has a diameter one third the tank diameter and is operated at a speed of 90 rpm. The density of the fluid is approximately I g cm-3. The reactor is used to culture an anaerobic organism that does not require gas sparging. The broth can be assumed Newtonian. As the cells grow, the viscosity of the broth increases. when the viscosity is 1000 times greater than water, estimate the power required to achieve turbulence.
#Question id: 14337
#SCPH05 I Biotechnology