# Recent questions and answers in Bioprocess Engineering and Process Biotechnology

1
In a batch culture of Penicillium chrysogenum, the maximum penicillin synthesis occurs during the lag phase exponential phase stationary phase death phase
2
A fed batch culture was operated with intermittent addition of glucose solution at a flow rate of $\text{200 ml h}^{-1}$. The values of $K_s,\: \mu_m$ and $D$ are $\text{0.3 g l}^{-1}, 0.4\:h^{-1}$ and $\text{0.1 h}^{-1}$, respectively. Determine the concentration of growth limiting substrate $(gl^{-1})$ in the reactor at quasi-steady state. ______________
3
At the end of a batch culture, glucose solution is added at a flow rate of $200 \: ml/h$. If the culture volume after $2$ h of glucose addition is $1000$ ml, the initial culture volume (in ml) is _________
4
Which of the following is employed for the repeated use of enzymes in bioprocesses? polymerization immobilization ligation isomerization
5
The degree of reduction of ethanol is_______
6
A solution was prepared by dissolving $\text{100 mg}$ of protein $X$ in $\text{100 ml}$ of water. Molecular weight of protein $X$ is $\text{15,000 Da};$ Avogadro’s number = $6.022\times 10^{23}$. Calculate the molarity$(\mu M)$ of the resulting solution. $66.6$ $6.6$ $0.67$ $0.067$
7
The maximum cell concentration $(\text{g l}^{-1})$ expected in a bioreactor with initial cell concentration of $\text{1.75 g l}^{-1}$ and an initial glucose concentration of $\text{125 g l}^{-1}$ is ($Y_{X/S} = 0.6\:g\:cell/g$ substrate) ____________.
8
A batch bioreactor is to be scaled up from $\text{10 to 10,000}$ liters. The diameter of the large bioreactor is $10$ times that of the small bioreactor. The agitator speed in the small bioreactor is $\text{450 rpm}$. Determine the agitator speed (rpm) of the large bioreactor with same impeller tip speed as that of the small bioreactor. ____________
9
A chemostat is operated at a dilution rate of $0.6\; h^{-1}$. At steady state, the biomass concentration in the exit stream was found to be $30\; gl^{-1}$The biomass productivity $(g\; l^{-1}h^{-1})$ after $3h$ of steady state operation will be ___________.
10
Moist heat sterilization of spores at $121 ^\circ C$ follows first order kinetics as per the expression: $\dfrac{dN}{dt}=-k_dN$ where, $N$ is the number of viable spores, $t$I is the time, $k_d$ is the rate constant and $\dfrac{dN}{dt}$ is the rate of change ... reduce the number of viable spores from an initial value of $10^{10}$ to a final value of $1$ is (up to two decimal places) __________
11
A microbial strain is cultured in a $100$ L stirred fermenter for secondary metabolite production. If the specific rate of oxygen uptake is $0.4 \: h^{-1}$ and the oxygen solubility in the broth is $8$ mg/L, then the volumetric mass transfer coefficient $(K_La)$ (in $s^{-1}$) of oxygen required to achieve a maximum cell concentration of $12$ g/L is (up to two decimal places) ___________
An aqueous solution containing $6.8$ mg/L of an antibiotic is extracted with amyl acetate. If the partition coefficient of the antibiotic is $170$ and the ratio of water to solvent is $85$, then the extraction factor is ________