Bacterial Physiology and Genetics: Elective Enrichment
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Questions and Answers

What is the primary goal of establishing specific cultural conditions in bacterial physiology?

  • To study the effects of natural selection
  • To favor the growth or survival of specific biotypes (correct)
  • To induce directed mutation
  • To promote spontaneous mutation
  • What is the term used to describe the concept of spontaneous mutation and natural selection?

  • Directed mutation
  • Preadaptation (correct)
  • Evolutionary adaptation
  • Inductive selection
  • What is the significance of the work of Luria and Delbruick (1943) in the context of this paper?

  • It supports the concept of preadaptation (correct)
  • It provides evidence for directed mutation
  • It introduces the concept of elective enrichment
  • It describes a new technique for replica plating
  • What is the term used to describe the concept of specific induction in contrast to natural selection?

    <p>Directed mutation</p> Signup and view all the answers

    What is the primary challenge in bacteriological work that the replica plating technique addresses?

    <p>The transfer of isolates to different media</p> Signup and view all the answers

    What is the primary purpose of the replica plating technique described in the paper?

    <p>To classify bacterial clones on a variety of media</p> Signup and view all the answers

    What is the purpose of the pile in velvet or velveteen fabrics used in replica plating?

    <p>To create space in a vertical plane for moisture</p> Signup and view all the answers

    How are the velveteen squares prepared for use in replica plating?

    <p>Cut into 12 cm squares, packed in petri dishes, and sterilized in an autoclave</p> Signup and view all the answers

    What is the purpose of inverting the agar plate carrying the initial colonies onto the fabric?

    <p>To transfer the growth pattern to the fabric</p> Signup and view all the answers

    What is an example of a characteristic that can be classified using replica plating?

    <p>Antibiotic-sensitivity spectra</p> Signup and view all the answers

    What is one of the advantages of using replica plating in routine tests?

    <p>It facilitates repetitive inoculations of many isolates on different media</p> Signup and view all the answers

    What can be varied according to specific needs in replica plating?

    <p>The type of initial growth to be replicated</p> Signup and view all the answers

    Study Notes

    Elective Enrichment in Bacterial Physiology and Genetics

    • Elective enrichment is a crucial technique in bacterial physiology and genetics, established by van Niel in 1949.
    • This technique involves creating cultural conditions that favor the growth or survival of specific biotypes, allowing for their isolation.

    Selection vs. Directed Adaptation

    • The concept of preadaptation, or spontaneous mutation, is contrasted with directed mutation, which suggests that a selective environment can direct adaptive heritable changes.
    • Many lines of evidence support the concept of preadaptation in various systems, including bacteriology and evolutionary biology.

    Replica Plating Technique

    • The replica plating technique facilitates the handling of large numbers of bacterial clones for classification on multiple media.
    • The technique involves using a velveteen fabric with a pile that provides space for moisture, preventing lateral smearing of any impression.
    • The fabric is sterilized and placed on a cylindrical support, and an agar plate carrying initial colonies is inverted onto the fabric to transfer the growth.
    • The imprinted fabric is then used to transfer replica-inocula to subsequent plates, allowing for rapid and efficient testing of multiple isolates on different media.

    Applications of Replica Plating

    • The technique can be used to classify traits such as antibiotic-sensitivity spectra, responses to bacteriophages, fermentation characters, and nutritional requirements.
    • It can also be applied to detect auxoheterotrophic mutants and has the potential to be used in other routine bacteriological practices.

    Advantages of Replica Plating

    • The technique allows for the precise reproduction of initial growth patterns, with the use of dry, hard agar yielding more faithful reproductions.
    • The type of initial growth can be varied according to specific needs, and a single initial plate can be used to imprint multiple fabrics.
    • Fabric squares can be washed, sterilized, and reused repeatedly, making the technique a convenient and efficient tool.

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    Description

    Explore the concept of elective enrichment in bacterial physiology and genetics, including its role in isolating specific biotypes and the debate on its impact on adaptive heritable changes. Learn about the cultural conditions that favor growth and survival and the relationship to evolutionary biology.

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