Product Recovery: Separation of Insoluble Products

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Questions and Answers

What is a major limitation of membrane filters?

Filter clogging

Which type of filtration system involves the culture broth being pumped across the membrane?

Ultrafiltration

How is the filter cake removed in a rotating drum filtration unit?

By being deposited on the drum surface and easily removed

What happens when gas is introduced into the liquid broth in the flotation process?

Cells and solid particles adsorb on gas bubbles Signup and view all the answers

Which filtration system uses collector substances like fatty acids for foam formation?

Flotation system Signup and view all the answers

In which type of filtration system does the filter cake get deposited on a rotating drum?

Dead-end filtration system Signup and view all the answers

What is the main purpose of Stage 1: Separation of Insoluble Products?

To separate solids from the fermentation broth Signup and view all the answers

Which method relies on gravity to settle cells down for separation?

Flotation Signup and view all the answers

What factor mainly determines the rate of sedimentation in the settling method?

Particle size and density Signup and view all the answers

Which technique is commonly used to separate molds, yeasts, and bacteria from the fermentation medium?

Filtration Signup and view all the answers

What is a key factor affecting the efficiency of filtration in separating biomass?

Size of the organism Signup and view all the answers

Which method involves forcing fluid through a filter media to separate solid particles from liquids?

Filtration Signup and view all the answers

What is the purpose of flocculation?

To form large aggregates of cells for easy removal Signup and view all the answers

Which of the following is NOT a factor affecting the process of flocculation?

Particle size Signup and view all the answers

What is the primary principle underlying centrifugation?

Density differences Signup and view all the answers

When is centrifugation most effective?

When the particles are large Signup and view all the answers

What is a limitation to large-scale industrial centrifugation?

Inability to separate fluid from solid particles Signup and view all the answers

Which type of industrial centrifuge is commonly used in pilot plants?

Tubular bowl centrifuge Signup and view all the answers

What is the main difference between a tubular bowl centrifuge and a disc centrifuge?

Disc centrifuge is used for low solid concentration fluids, while tubular bowl centrifuge is used for high solid concentration fluids. Signup and view all the answers

How does a disc centrifuge function in separating solids from fluids?

The feed/slurry is fed through a central tube, and the clarified fluid moves upwards. Signup and view all the answers

What is the main purpose of a decanter or scroll centrifuge?

To separate fluids with high solid concentration. Signup and view all the answers

Why is the release of intracellular products important in biotechnological processes?

To maximize and release compounds located within cells for further processing. Signup and view all the answers

Which type of method can be used to disintegrate or disrupt microorganisms or cells?

Physical, chemical, or enzymatic methods Signup and view all the answers

Why does the selection of a particular method for cell disruption depend on the nature of the cells?

Due to a wide variation in cell disruption properties among different cells. Signup and view all the answers

What is the main purpose of grinding with glass beads in cell disruption?

To force cells against the vessel walls, causing them to break Signup and view all the answers

How do detergents aid in disrupting bacterial cells?

By solubilizing phospholipids in the cell membrane Signup and view all the answers

Which of the following is a common organic solvent used for disrupting cells?

Methanol Signup and view all the answers

What effect does alkali treatment have on bacterial cells?

It enhances DNA extraction from cells Signup and view all the answers

How are bacterial cells lysed in non-mechanical methods using enzymes?

By targeting peptidoglycan with lysozyme Signup and view all the answers

Which method is known for disrupting lipid:lipid, lipid:protein, and protein:protein interactions within cells?

Organic solvent treatment Signup and view all the answers

Study Notes

Cell Disruption Methods

Grinding with glass beads involves breaking cells by forcing them against the walls of a vessel at high speed.
Detergents are used to rupture mammalian cells by solubilizing their phospholipids and disrupting lipid:lipid, lipid:protein, and protein:protein interactions.
Lysozyme is used in conjunction with detergents to disrupt bacterial cells.
Fungal cells require weakened cell walls before detergents can act.
Organic solvents like toluene, ether, and phenyl ethyl alcohol solubilize phospholipids and denature proteins, disrupting cell membranes.
Alkali treatment is a fast, reliable, and relatively clean method to isolate DNA from cells and extract bacterial proteins.

Cell Harvesting (Separation of Insoluble Products)

Cell harvesting involves separating biomass, insoluble particles, and macromolecules from fermentation broth.
Methods include settling, filtration, flotation, flocculation, and centrifugation.
Settling (sedimentation) is a low-cost method that depends on size and weight, used in the alcohol industry.
Filtration is widely used to separate molds, yeasts, and bacteria from fermentation medium.
Flotation involves introducing gas into the liquid broth, forming bubbles that cells adsorb to, and collecting the foam layer.
Coagulation-flocculation involves adding agents to form large aggregates that settle down for easy removal.

Centrifugation

Centrifugation separates solid particles from liquid phase based on density differences.
It is most effective for large particles and low liquid viscosity.
Types of industrial centrifuges include:
- Tubular bowl centrifuge: simple, commonly used in pilot plants, can be operated in batch or continuous mode.
- Disc centrifuge: separates fluids with low solid concentration, used in pilot plants.
- Scroll centrifuge or decanter: used to separate fluids with high solid concentration, generally used in industrial scale.

Release of Intracellular Products

Intracellular products must be released from cells for further processing and final isolation.
Methods of cell disruption include physical, chemical, and enzymatic methods.
The selection of a method depends on the nature of the cells.

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