Antibiotics in Action

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    Biology Activity
    Culturing Bacteria
    Isolation and Identification

    Major Concept

    The activity demonstrates the basic principles of culturing microorganisms and of cell staining.

    Level and Expected Student Background

    These activities are appropriate for an introductory-level biology course. The students should be familiar with the basics of culturing microorganisms and should understand Koch's Postulates for identifying pathogens.
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      General Safety Guidelines
      Microbiology Safety Guidelines
      Major Concept
      Level and Expected Student
      Background
      Time
      Safety
      Materials and Apparatus
      Advance Preparation
      Relevant National Science
      Education Standards
      Relevant New Jersey State
      Science Education Standards

    Time

    Lab #1 requires two lab periods, several days apart. Lab #2 requires two lab periods on consecutive days.

    Safety

    General Safety Guidelines
    Microbiology Safety Guidelines

    Materials and Apparatus

    Lab #1 Bacterial Enrichment Using a Carrot Medium

    • Carrots that have been cleaned, cut in half, then cut into pieces 5-8 cm in length
    • Beaker
    • Forceps
    • Isopropyl alcohol
    • Petri dish
    • Filter paper
    • Microscope
    • Microscope slides
    • Transfer needle or loop
    • Test tube
    • Test tube rack

    Lab #2: Enrichment of Microbes Using a Milk Medium

    • Fresh milk
    • Curdled sour milk
    • Transfer loop
    • 5 test tubes
    • 5 sterile petri dishes
    • Calcium carbonate (CaCO3)
    • Agar

    Smear Preparation, Gram Staining, and Spore Staining

    • Microscope slide
    • Bunsen burner
    • Transfer loop or needle
    • Beral® pipette
    • Gram's iodine solution
    • Hucker's ammonium oxalate crystal violet stain
    • 95% ethyl alcohol
    • Safranine
    • 6% aqueous malachite green
    • 0.25 % aqueous safranine

    Advance Preparation

    Lab #2 requires sour milk, so leave the milk unrefrigerated for several days before conducting the experiment. Once curds form, the milk is ready to be used as a source of bacteria. Remember that fresh unspoiled milk is also needed for the experiment.

    Relevant National Science Education Standards

      Unifying Concepts and Processes — The activities examine the chemical behavior of biological systems and they involve the observation of change and the collection of evidence.

      Science as Inquiry — The activities involve conducting systematic observations, interpreting and analyzing data, drawing conclusions, and communicating results.

      Physical Science — The activities concern the behavior of matter in living systems.

      Life Science — The activities deal with the nature of the cell and the behavior of matter in living systems.

      Science and Technology — The activities deal with the science behind a technology used in fighting disease.

      Science and Personal and Social Perpectives — The activities examine the role of science in facing personal and community health challenges.

      History and Nature of Science — The activities illustrate the nature of scientific knowledge, offer historical perspective, and demonstrate science as a human endeavor.

    Relevant New Jersey State Science Education Standards

      5.1 The activities involve conducting systematic observations, interpreting and analyzing data, drawing conclusions, and communicating results.
      5.2 The background information describes the history of staining and shows how people of various cultures have contributed to it.
      5.4 The activities demonstrate a science-based technology used infighting disease.
      5.5 The activity reinforces understanding of basic cell biology.
      5.6 The activity examines the behavior of matter in living systems.

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