Biochemical Miscellaneous
- In an exponentially growing batch culture of Saccharomyces cerevisiae, the cell density is 20 gl–1 (DCW), the specific growth rate (µ) is 0.4h–1 and substrate uptake rate (ν) is 16 gl–1h–1. The cell yield coefficient Yx/s will be
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Yield coefficient = mass of new cells formed / mass of substrate consumed
New cells mass formed = cell density x specific growth rate = 20 × 0.4 = 8
Substrate consumed = 16 g/l/h Yield coefficient = 8 = 0.5 16
Correct Option: D
Yield coefficient = mass of new cells formed / mass of substrate consumed
New cells mass formed = cell density x specific growth rate = 20 × 0.4 = 8
Substrate consumed = 16 g/l/h Yield coefficient = 8 = 0.5 16
- Match the downstream processes in Group I with the products in Group II.
Group I Group II P. Solvent extraction 1. Lactic acid Q. Protein-A linked affinity 2. Penicillin chromatography R. Extractive distillation 3. Monoclonal antibody S. Salting out 4. Lipase
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Solvent extraction is a method for processing materials by using a solvent to separate the parts. It can be used for penicillin extraction.
Affinity chromatography is the preferred method of bioselective adsorption and subsequent recovery of a compound from an immobilized ligand. Each is designed for highly specific and efficient purification of proteins and related compounds like monoclonal antibody.
Extractive distillation is defined as distillation in the presence of a miscible, high boiling, relatively non-volatile component, and the solvent that forms no azeotrope with the other components in the mixture. It can be used for lactic acid recovery.
Salting out is a purification method that utilizes the reduced solubility of certain molecules in a solution of very high ionic strength. Crude lipase can be purified by using salting out method.Correct Option: A
Solvent extraction is a method for processing materials by using a solvent to separate the parts. It can be used for penicillin extraction.
Affinity chromatography is the preferred method of bioselective adsorption and subsequent recovery of a compound from an immobilized ligand. Each is designed for highly specific and efficient purification of proteins and related compounds like monoclonal antibody.
Extractive distillation is defined as distillation in the presence of a miscible, high boiling, relatively non-volatile component, and the solvent that forms no azeotrope with the other components in the mixture. It can be used for lactic acid recovery.
Salting out is a purification method that utilizes the reduced solubility of certain molecules in a solution of very high ionic strength. Crude lipase can be purified by using salting out method.
- Determine the correctness or otherwise of the following Assertion (A) and the Reason (R).
Assertion : In synchronous culture, majority of the cells move to next phase of the cell cycle simultaneously.
Reason : Synchronous culture could be obtained by starving cells for essential nutrient components.
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Synchronous growth of a bacterial population is that during which all bacterial cells of the population are physiologically identical and in the same stage of cell division cycle at a given time. Synchronous growth helps studying particular stages or the cell division cycle and their interrelations. A synchronous culture can be obtained either by manipulating environmental conditions such as by repeatedly changing the temperature or by adding fresh nutrients to cultures as soon as they enter the stationary phase, or by physical separation of cells by centrifugation or filtration. Synchronous cultures rapidly lose synchrony because not all cells in the population divide at exactly the same size, age or time.
Correct Option: B
Synchronous growth of a bacterial population is that during which all bacterial cells of the population are physiologically identical and in the same stage of cell division cycle at a given time. Synchronous growth helps studying particular stages or the cell division cycle and their interrelations. A synchronous culture can be obtained either by manipulating environmental conditions such as by repeatedly changing the temperature or by adding fresh nutrients to cultures as soon as they enter the stationary phase, or by physical separation of cells by centrifugation or filtration. Synchronous cultures rapidly lose synchrony because not all cells in the population divide at exactly the same size, age or time.
- In a well aerated and agitated microbial culture, the ‘supply' of oxygen is equal to ‘demand' (uptake) of the growing culture. The KLa for such a system will be (KLa = volumetric mass transfer coefficient, C* = dissolved oxygen concentration in liquid in equilibrium with gaseous oxygen,C = instantaneous value of dissolved oxygen concentration, ‘r' = specific oxygen uptake rate per unit weight of cells, X = dry weight of the cells per unit volume)
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The “gas out-gas in” method can directly determine the volumetric mass transfer coefficient in a bioreactor system and provide estimates of the volumetric microbial oxygen uptake rate and the average oxygen saturation concentration at the gas-liquid interface. The rate of oxygen transfer from the bubble air to the liquid phase is described by the equation :
dCL / dt = KLa (C* – CL)
⇒ KLa = dCL/dt * 1/ (C* – CL)
⇒ KLa = r*X/(C* – CL)
Where r*X = dCL/dt, r is the specific oxygen uptake rate per unit weight of cells and X is the dry weight of cells per unit volume.
For reliable measurements, deconvolution of the oxygen probe measurements must be made. Correct Option: A
The “gas out-gas in” method can directly determine the volumetric mass transfer coefficient in a bioreactor system and provide estimates of the volumetric microbial oxygen uptake rate and the average oxygen saturation concentration at the gas-liquid interface. The rate of oxygen transfer from the bubble air to the liquid phase is described by the equation :
dCL / dt = KLa (C* – CL)
⇒ KLa = dCL/dt * 1/ (C* – CL)
⇒ KLa = r*X/(C* – CL)
Where r*X = dCL/dt, r is the specific oxygen uptake rate per unit weight of cells and X is the dry weight of cells per unit volume.
For reliable measurements, deconvolution of the oxygen probe measurements must be made.
- Structured William's model
P. can describe the changes in intracellular components of the cell during growth
Q. cannot describe the death phase of the cells
R. can describe the variation of size of cells in the different phases of growth
S. cannot describe the lag period of growth
Which one of the following is correct?
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Williams proposed a simple structured model that divides the biomass into two parts: Part 1 is composed of intermediates, enzymes, and other entities involved in the formation of materials used for synthesis of structural and genetic material; Part 2 is the structural and genetic part of the biomass. It can be used to describe the change in intracellular components during cell growth. In the different phases of cell growth, this model enables analytical depiction and explanation of the variation in the size of the cells. But the model is not structured for reasoning with the death phase of the cells.
Correct Option: B
Williams proposed a simple structured model that divides the biomass into two parts: Part 1 is composed of intermediates, enzymes, and other entities involved in the formation of materials used for synthesis of structural and genetic material; Part 2 is the structural and genetic part of the biomass. It can be used to describe the change in intracellular components during cell growth. In the different phases of cell growth, this model enables analytical depiction and explanation of the variation in the size of the cells. But the model is not structured for reasoning with the death phase of the cells.
