Plant roots produce valuable chemicals in vitro. A batch culture of Atropa bella
ID: 82627 • Letter: P
Question
Plant roots produce valuable chemicals in vitro. A batch culture of Atropa belladonna roots at 25°C is established in an air-drived reactor as shown in the figure. Because roots cannot be removed during the operation of the reactor, it is proposed to monitor growth using integral transient mass balances.
1425 g nutrient medium contaning 3% glucose and 1.75% NH3 is fed into de bioreactor; the remainder of the medium can be considered water. Air at 25°C and 1 atm is sparged into the bioreactor at a rate of 22 cm3/min. During a 10-day culture period, 47 L O2 and 15 L CO2 are collected in the off-gas. After 10 days, 1110 g liquid containing 0.063% glucose and 1.7% dissolved NH3 is drained from the vessel. The ratio of fresh weight to dry weight for roots s known to be 14:1.
What dry mass of roots is produced in 10 days?
Nutrient medium Roots Off-gas Drained liquid Air-driven reactor AirExplanation / Answer
Using the information we can calculate the mass and molar rates of glucose, ammonia, water into the bioreactor:
For glucose:-
Mass rate = 0 .03 * 1425
= 42.75 g/run
Molar rate = 42.75 / 180
= 0.2375 mol/run
Similarly for ammonia the mass and molar rates are – 24.94 g/run and 1.47 mol/run and for water 1357 g/run and 75.4mol/run respectively.
Though glucose is the limiting factor it is not totally consumed.
The bioreactor is sealed for 10 days, therefore plant biomass cannot enter or leave the culture. The mass increases as the plant grows.
The accumulation of mass inside the bioreactor can be calculated using accounting equation for dyanamic system;
Biomass = 0 – 0 + 3.37 * 0.2336 mol/run
= 0.787 mol/run
The accumulation of dry plant biomass in molar units =
0.787 * 26.45 = 20.8 g / run
Therefore the dry mass of Atropa belladonna roots in the culture at 10 days is 20.8 g.