Deck 13: Bioprocessconsiderations in Usingplant Cell Cultures

Question 1

The uptake of the auxin, indole acetic acid (or IAA), by suspension cultures of Parthenocis-
sus sp. is nearly zero order at 1 nmol/mg dry cell weight-min. The diffusivity of IAA in water
is Beads of calcium alginate are most conveniently made as spheres with a
4-mm diameter. Assume the beads are made 25% by volume of plant cells. Assume the plant
cells are 90% water and that the diffusivity of IAA in the gel is the same as in water. If the ex-
ternal concentration is maintained at 2 mmol, will IAA penetrate to the center of the bead?

Answer 1

According to the given data:
The uptake of auxin and indole acetic acid in the suspension culture of Parthenocisus sp. is zero order at = 1 nmol/mg dry cell weight-min.
The diffusivity of IAA in water is = 5 x 10 -6 cm 2 /s.
Beads of calcium alginate make spheres with = 4-mm diameter.
Beads are made of = 25% by volume of plant cells.
The external concentration = 2 µmol.
Using equation 9.65 to see if at , Then the substrate concentration is calculated as below:
To calculate for the bead:
Mass of cells/bead = 0.88 mg dry wt/bead. = (1 × 10 -³ µ mol/mg.min) (0.88 ng/ bead)
= 0.88×10 -3 µ mol/min.bead (1 min/60 s)(1 bead/ )
= 0.438×10 -3 µ mol/s-cm 3
From 9.65 For, 2 µ mol/cm 3 -0.584 µ mol/cm 3. 1.4 µ mol/cm 3 at Therefore, the answer is yes as it will penetrate into the center of the bead.

Question 2

Gel-immobilized cells of Papaver somniferum (opium poppy) can make codeine from
codeinone. The rate of codeinone uptake is first order, with a rate constant of cells dry weight-s. The diffusivity of codeinone in the gel is For a gel particle
of 4-mm diameter with a 25% volume loading of cells (95% water), what will be the effec-
tiveness factor?

Answer 2

According to the equation 9.63. The first order reaction constant needs to be based on the whole pellet.
Dry weight is = 5 %.
Mass of cells/bead = 0.44 mg/bead.
Cell concentration = 0.44 mg/0.0335 cm 3 = 13.1 g/l
Thus the rate constant is k = 3.3 × 10 -8 (13.1) = 4.3 × 10 -7 s -1
For, 0.4 cm diameter bead 0.0335 cm 3 and 0.503 cm 2 First order so Thus, for first order reaction 0.0306 Clearly, diffusional limitations is not important.

Question 3

The of a small bubble column (2 l) has been measured as at an airflow of 4 l/m in.
If the rate of oxygen uptake by a culture of Catharanthus roseus is 0.2 mmol dry
weight-h and if the critical oxygen concentration must be above 10% of saturation (about
8 mg/l), what is the maximum concentration of cells that can be maintained in the reactor?

Answer 3

Fom the equation 10.1: The maximum concentration of cells is: According to the given data: 8 mg/l. 0.10 0.2 m mol O 2 / g dry wt-h

Question 4

C. roseus cells immobilized in Ca-alginate beads of diameter 0.5 mm are used for production
of indole alkaloids (IA) in a fluidized-bed bioreactor. The rate limiting nutrient is glucose
and no intraparticle diffusion limitations exist. Use the following data: Flow rate of the feed:
Q = 1 l/h, Glucose in the feed: Plant Cell Concentration: X = 6 g/l reac. The rate
constant for IA formation: Column diameter: Growth is negligible and Monod kinetics is valid. Determine the following:
a. For 95% glucose conversion determine required hydraulic residence time, volume, and
the height of the column
b. If
glu, determine IA concentration in the effluent and the productivity.