Strain Improvement in Microbiology

Questions and Answers

Which factor is crucial in selecting an organism for fermentation processes?

The number of genes it possesses

The geographic location of the organism

The nutritional characteristics of the organism (correct)

The color of the organism

Which of the following is essential for strain improvement through genetic manipulation?

The organism's appearance

The organism's geographic diversity

The stability of the organism (correct)

The reproductive lifespan of the organism

What aspect of an organism can significantly reduce the cooling costs in large-scale fermentation?

Having an optimum temperature above 40° C (correct)

Producing secondary metabolites

Small cell size

Rapid growth rate

How can feedback inhibition be addressed in an organism during strain improvement?

By enhancing the permeability of the cell membrane Signup and view all the answers

What type of mutants may lead to higher yields by disrupting metabolic control mechanisms?

Auxotrophic mutants Signup and view all the answers

What is a common method to isolate mutants that do not produce pathways' feedback inhibitors?

Overlay of agar method Signup and view all the answers

Which of the following is NOT a criterion for selecting an organism for industrial fermentation?

The color of the product Signup and view all the answers

What is the purpose of using recombination systems in the context of strain improvement?

To increase genetic diversity in organisms Signup and view all the answers

What is the role of chloramphenicol in its own synthesis regulation?

It represses arylamine synthetase. Signup and view all the answers

Which method involves the transfer of genetic material through direct cell-to-cell contact?

Conjugation Signup and view all the answers

What characterizes a suitable vector DNA molecule for recombinant DNA technology?

It should have a site for foreign DNA integration. Signup and view all the answers

What is the result of mutating organisms to become resistant to toxic secondary metabolites?

Isolation of mutants that can produce the secondary metabolite. Signup and view all the answers

What characteristic is NOT typically associated with improved industrial strains of microbes?

Increased yield of products Signup and view all the answers

Which of the following techniques involves the manipulation of protoplasts?

Transformation Signup and view all the answers

How are revertants primarily isolated in a research setting?

From mutants that regain their ability to produce a secondary metabolite. Signup and view all the answers

What is a common method for detecting the presence of foreign genes in recombinant DNA technology?

Drug resistance tests. Signup and view all the answers

What is the primary goal of isolating analogue-resistant mutants in metabolic production?

To improve the availability of metabolic precursors Signup and view all the answers

Which of the following best describes the function of feedback inhibitors in metabolic pathways?

They mimic natural products to control enzyme activity Signup and view all the answers

Which technique is specifically mentioned for isolating mutants that produce improved yields of secondary metabolites?

Gradient plate technique Signup and view all the answers

What type of mutants can be isolated to bypass inhibition from natural end products?

Feedback-inhibition resistant mutants Signup and view all the answers

In the context of lysine production, what does the presence of S-(2 aminoethyl) cysteine (AEC) illustrate?

AEC acts as a feedback inhibitor mimicking lysine Signup and view all the answers

What characteristic of the analogue-resistant mutant aids in overproducing the targeted secondary metabolite?

Resistance to the natural end product inhibition Signup and view all the answers

What is one expected effect of lysine analogue-resistant mutants of Brevibacterium flavum?

Elevated lysine production levels Signup and view all the answers

Which pathway is affected when tryptophan analogue mutants are isolated?

It enhances the synthesis of secondary metabolites Signup and view all the answers

Study Notes

Selection Criteria for Organisms in Strain Improvement

Nutritional characteristics should allow for the use of cheap or predetermined media, such as methanol as an energy source.
Optimum temperature above 40°C reduces cooling costs during large-scale fermentation.
Organism compatibility with equipment and process suitability is crucial.
Stability and amenability to genetic manipulation are essential traits for the chosen organism.
Productivity should be measured by substrate conversion efficiency and yield rate.
Ease of product recovery from the culture is an important consideration.

Induced Mutants for Enhanced Metabolite Production

Induced mutants can be selected to synthesize higher levels of primary metabolites.
Secondary metabolites can be enhanced by selecting mutants when directed selection is challenging.

Feedback Inhibition and Repression Modifications

Modifications can lead to organisms that retain only certain control over metabolic pathways.
Alterations may make an organism lose inhibitory end products due to cell membrane permeability issues.
Experimental modifications can allow an organism to ignore presence of normal control metabolites.

Isolation Techniques for High-Producing Strains

Auxotrophic mutants, when isolated correctly, can lead to higher production strains.
Techniques include overlaying agar and using enrichment cultures for visual identification.

Analogue Resistant Mutants

Isolation of mutants resistant to feedback inhibitors can lead to enhanced production when an analogue mimics a control product.
Example: Lysine analogue-resistant mutants of Brevibacterium flavum can aid in increased lysine production.
Gradient plate techniques can be utilized for isolation.

Secondary Metabolite Production Enhancements

Resistant mutants may be selected against primary metabolic precursors to enhance secondary metabolite production.
Example: Mutants of Pseudomonas aureofaciens showcased increased antibiotic production when resistant to tryptophan analogues.

Mechanisms of Resistance

Isolation of mutants resistant to feedback effects of their metabolites can promote continuous production.
Mutants may also be resistant to toxic effects of secondary metabolites during production.

Reversion and Recombination Techniques

Reversion methods involve selecting mutants which regain the ability to synthesize important metabolites.
Various recombination techniques include:
- Parasexual cycles
- Protoplast fusion
- Transformation
- Conjugation
- Transduction
- Recombinant DNA (rDNA) techniques

Recombinant DNA Technology

A vector must be capable of replicating in the host cell, ideally containing a site for DNA insertion.
Techniques for DNA splicing and introducing vectors into host cells are essential for successful genetic manipulation.
Selection methods may include drug resistance or visible traits that indicate the presence of inserted genes.

Industrial Strain Improvement Beyond Yield

Focus on developing stable strains, strains resistant to infection, and non-foaming strains to improve efficiency in production processes.

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Description

This quiz focuses on the criteria for selecting organisms for strain improvement, particularly in relation to nutritional characteristics and optimum temperature for growth. It discusses the significance of using cost-effective media and temperature management in biological processes, which can enhance productivity and reduce expenses.