Antibiotics in Action

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    Biology Activity
    Resistance in Bacteria

    Major Concept

    Natural selection operates at various levels throughout the living world, from single celled organisms to multicellular creatures as large as whales. Bacterial resistance to lethal environmental factors illustrates, on the microscopic level, natural selection in a time span of mere days.

    Level and Expected Student Background

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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

    This activity is best done with students who can follow detailed instructions and respect safety precautions when working with bacteria. They should be skilled in using microscopes with oil-immersion lenses. This exercise requires a series of days for experimentation and follow-through. Students must be responsible for accurate note-taking while in the lab. Because the lab requires five days, the teacher needs to schedule the activities to begin at the beginning of the week. Otherwise, students will have to complete the experiment over a weekend.

    Time

    Each procedure would benefit from students having double periods. As noted in the previous section on student background, the starting day is important in order to avoid a weekend in the middle of the experiment. For summation of the results, allow an additional two day period.

    Safety

    General Safety Guidelines
    Microbiology Safety Guidelines

    1. Students should wear safety goggles at all times.

    2. Students should understand the basics of sterile techniques and working safely with microbes. Make sure they read the Microbiology Safety Guidelines linked above.

    3. Students should understand the dangers of working with ultraviolet light sources. They should not look directly at UV sources, particularly if they are trying to determine if the light source is turned on. Rather, the light source should be directed onto a white sheet of paper or paper sprayed with starch that will clearly show a blue-purple image. Special goggles that protect against UV or sunglasses that are clearly labeled as UV blockerswould be useful.

    4. It is suggested that students wear lab coats (inexpensive paper coats that are durable and reusable are available from a variety of biological supply companies) and inexpensive lab gloves (rolls of these ambidextrous gloves are also available from supply companies).

    5. Provide disinfectant clean-up materials.

    6. Provide a method for separating bacterial media and contaminated materials from normal trash. People handling the bacteria-contaminated material should be wearing gloves.

    Materials and Apparatus

    • Stock culture of Escherichia coli from biological supply company
    • Nutrient broth medium (sterile)- peptone/beef
    • Nutrient agar medium (sterile)- peptone/beef
    • Agar plates with lids
    • Sterile cotton
    • UV source (15 watt, in fluorescent desk lamp if not in a separate, commercial holder)
    • UV goggles (or sunglasses approved for blocking UV)
    • Transfer loops
    • Flame source: Bunsen burner or alcohol lamp
    • Incubator, set at 38ēC
    • Stop watch
    • Marking pencils

    Relevant National Science Education Standards

      Unifying Concepts and Processes — The activity deals with systems, order, and organization; evidence, models, and explanations; and change, constancy, and measurement.

      Science as Inquiry — The activity teaches abilities necessary to do scientific inquiry and understandings about scientific inquiry.

      Life Science — The activity involves the cell, behavior of organisms, and matter, energy, and organization of living systems.

      Science and Technology — The activity teaches understandings about science and technology.

      Science in Personal and Social Perspectives — The activity addresses population growth, natural resources, and environmental quality.

      History and Nature of Science — The activity involves science as a human endeavor, the nature of scientific knowledge, and historical perspectives.

    Relevant New Jersey State Science Education Standards

      5.1 The activity teaches abilities necessary to do scientific inquiry and understandings about scientific inquiry.
      5.4 The activity teaches understandings about science and technology.
      5.5 The activity involves the cell, behavior of organisms, and matter, energy, and organization of living systems. The activity also demonstrates natural selection in action.
      5.10 The activity concerns the risks of science and the effects of human activity on the environment in its exploration of how antibiotic misuse can create resistant bacteria.

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