Microbial Product Isolation Techniques

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Questions and Answers

What unit operation is commonly used for primary isolation of soluble microbial products?

Sublimation

Extraction (correct)

Condensation

Crystallization

Which statement is true about the extraction of proteins using organic solvents?

All proteins can be extracted using organic solvents.

Proteins are easily extracted with organic solvents.

Proteins are denatured upon contact with organic solvents. (correct)

Organic solvents enhance protein stability.

What does a high K value indicate regarding the liquid-liquid extraction process?

That the extraction will be challenging.

That the phases will not separate efficiently.

That extraction is likely to be straightforward. (correct)

That a multistage extraction is always required.

In the context of extraction processes, what is meant by 'immiscible liquids'?

Liquids that do not mix and form distinct layers. Signup and view all the answers

Which of the following operations is NOT a method mentioned for recovering soluble products?

Distillation Signup and view all the answers

Which method is suitable for extracting biomolecules without the risk of denaturation?

Liquid-liquid extraction using immiscible liquid phases with polymers. Signup and view all the answers

What is a potential limitation of a low K value in liquid-liquid extraction?

It signifies difficulty in achieving separation and may require multiple stages. Signup and view all the answers

Which of the following products is least likely to be extracted using common organic solvents?

Proteins. Signup and view all the answers

What is the role of polymers in aqueous two-phase extraction?

To facilitate the separation of proteins and organelles Signup and view all the answers

How is the maximum possible enzyme recovery determined in a two-phase extraction using partition coefficients?

By applying the partition coefficient to the volume ratio of the phases Signup and view all the answers

In a counter-current extraction system, how do the flows of the feed and extracting solvent interact?

They pass through the cascaded vessels in opposite directions Signup and view all the answers

What happens in a single-stage extraction process?

One feed stream contacts one extraction solvent stream Signup and view all the answers

What is the general purpose of using more than one extraction stage in a bioproduct recovery process?

To achieve higher recovery rates of the desired product Signup and view all the answers

What happens to the net charge of proteins when suspended in near-neutral pH?

They carry a net negative charge. Signup and view all the answers

Which of the following statements about aqueous two-phase systems is true?

They contain more than 80% of aqueous content Signup and view all the answers

Which factor is NOT important when selecting a salt for protein precipitation?

The salt must be expensive. Signup and view all the answers

What is the main advantage of countercurrent operation in solvent utilization?

It is more efficient than batch and co-current systems. Signup and view all the answers

What complication arises in a co-current extraction setup?

Higher initial concentration leads to lower extraction efficiency Signup and view all the answers

What is the significance of the partition coefficient in the context of enzyme extraction?

It measures the relative concentration of the enzyme in both phases Signup and view all the answers

In the batch steroid extraction process with a water to solvent ratio of 82, what can be inferred about the initial concentration in the organic phase?

It will be significantly higher than in the aqueous phase. Signup and view all the answers

What is the isoelectric point of a protein?

The pH at which the protein carries zero net charge. Signup and view all the answers

What is the equilibrium constant for the extraction of actinomycin D in clarified fermentation beer?

57 Signup and view all the answers

What role do hydrophobic regions of a protein play in its interactions with other proteins?

They create sites of attraction between proteins. Signup and view all the answers

What impacts the tendency of a protein to precipitate during purification?

The solubility characteristics of the solvent and protein properties. Signup and view all the answers

Which of the following methods is used to remove residual salt from precipitates formed by salting-out?

Dialysis Signup and view all the answers

Why is it important to avoid a large heat of solution when using salt for protein precipitation?

To avoid denaturing the product or affecting solubility. Signup and view all the answers

In a staged extractor planning to recover 99% of the antibiotic, what is critical to calculate?

The number of stages required. Signup and view all the answers

What is the role of precipitants in the purification of intracellular proteins?

They reduce the solubility of proteins, leading to precipitation. Signup and view all the answers

What is the primary cause of repulsion between similarly charged protein molecules in solution?

Formation of hydration layers. Signup and view all the answers

What effect does the addition of organic solvent at low temperatures have on protein precipitation?

It reduces the dielectric constant of the solution. Signup and view all the answers

What is necessary for water-soluble proteins to maintain their structure in solution?

Polar, hydrophilic amino acids are primarily on the surface. Signup and view all the answers

What factor is NOT directly affecting the efficiency of solvent utilization in the extraction process?

The temperature of the environment. Signup and view all the answers

Study Notes

Primary Isolation of Products

Microbial products are often soluble and need to be separated before further purification.
Extraction, adsorption, ultrafiltration, and chromatography are common primary isolation techniques.
These methods rely on mass transfer between phases.

Extraction

Extraction involves transferring a solute from one phase to another.
This is typically achieved by contacting two immiscible liquids.
Organic solvents are often used for extracting low molecular weight antibiotics.
Proteins are typically not extracted with organic solvents, as they can be denatured.
Aqueous two-phase extraction is a suitable method for extracting enzymes and other sensitive proteins.

Liquid-Liquid Extraction

The partition coefficient (K) determines the ease of extraction.
A high K value indicates good separation and a single-stage system may be sufficient.
A low K value signifies difficult extraction and may require a multistage process.

Aqueous Two-Phase Liquid Extraction

Aqueous two-phase systems are formed by dissolving incompatible polymers, like polyethylene glycol (PEG) and dextran, in water.
Used for recovering biomolecules, proteins, cell fragments and organelles.

Batch and Staged Extraction

Single-stage extraction involves contacting one feed stream with one extraction solvent stream.
Multi-stage extraction is often necessary for high bioproduct recovery.
Co-current and counter-current extraction processes are common.
Counter-current extraction is the most efficient due to its ability to utilize solvent better.

Analytical Methods

The efficiency of extraction can be determined using analytical methods.
Batch and continuous extraction methods are used to measure the amount of product extracted.

Precipitation

Precipitation is a common method for recovering products from culture broths.
It reduces the solubility of the product, causing it to precipitate out of solution.
The tendency of a protein to precipitate depends on factors like pH, ionic strength, dielectric constant, size, charge, and hydrophobicity.
Precipitation can be influenced by attractive and repulsive forces between neighboring protein molecules in solution.
Isoelectric point is the pH at which a protein carries zero net charge, which affects its precipitation.
Salting out is a common precipitation method, where the addition of a high concentration of salt reduces the solubility of the protein.

Salting Out

Increasing the concentration of salt disrupts the hydration layer around proteins, exposing hydrophobic zones and promoting precipitation.
The salt used should be inexpensive, highly soluble in aqueous solutions, and have a low heat of solution to avoid affecting the product's stability.
Salt precipitates containing protein need to be desalted using techniques like dialysis, diafiltration, or gel chromatography.

Other Precipitation Methods

Precipitation can also be achieved by:
- Adding organic solvents at low temperatures, which reduce the dielectric constant of the solution.
- Using a pH change to alter the charge of the protein.
- Using specific ligands that bind to the protein and cause precipitation.

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Description

This quiz covers the primary isolation methods for microbial products, focusing on techniques like extraction, adsorption, ultrafiltration, and chromatography. Learn about the principles of liquid-liquid extraction and factors affecting extraction efficiency such as the partition coefficient. Explore different strategies for isolating various types of microbial compounds.