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2.9: Results

  • Page ID
    122967
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    1. Draw and describe the growth seen in each of the four broth cultures.

    ttube.jpg ttube_hjk4.jpg ttube_xxzc.jpg ttube_fx77.jpg 

    Bacillus subtilis

    Growth =

    Escherichia coli

    Growth =

    Micrococcus luteus

    Growth =

    Mycobacterium phlei

    Growth =

    2. Observe the growth in the slant cultures and stab cultures for pigmentation and purity.

    slantslab2.JPG
    Agar Slant Cultures of Bacteria (Copyright; Gary E. Kaiser, Ph.D. The Community College of Baltimore County, Catonsville Campus CC-BY-3.0)

    3. Using the terms in the Appendix A, compare a single colony of B. subtilis with a single colony of M. luteus. Use a hand lens or a dissecting microscope to magnify the colony.

    Single Colonies of Bacillus subtilis

    Isolated Colonies of Escherichia coli

    Single Colonies of Micrococcus luteus

    Single Colonies of Mycobacterium phlei

    colonybs.JPG E,coli_colonies_re46.jpg colonyml_11.JPG Mphlei_colonies.jpg
    Copyright; Gary E. Kaiser, Ph.D. The Community College of Baltimore County, Catonsville Campus CC-BY-3.0 Image: Escherichia coli on Luria agar. © Kevin Hedetniemi and Min-Ken Liao, authors.
    Licensed for use, ASM MicrobeLibrary.
    Copyright; Gary E. Kaiser, Ph.D. The Community College of Baltimore County, Catonsville Campus CC-BY-3.0 Copyright; Gary E. Kaiser, Ph.D. The Community College of Baltimore County, Catonsville Campus CC-BY-3.0
    characteristics
    B. subtilis
    M. luteus

    Form of colony

    form.jpg

       

    Elevation

    elevat.jpg

       

    Margin (edge)margin.jpg

       

    Surface

    surface.jpg

       
    Optical characteristics:
    Opaque, transluscent, dull, mucoid, dry, etc.
       

    Pigmentation

    Pigments can be divided into two basic types: water insoluble and water soluble. If the pigment is water insoluble, as in the case of most chromogenic bacteria, it does not diffuse out of the organism. As a result, the colonies are pigmented but the agar remains the normal color. If the pigment is water soluble (as in the case of Pseudomonas aeruginosa) it will diffuse out of the organism into the surrounding medium. Both the colonies and the agar will appear pigmented.

    State the color of the pigment (red, orange, green, etc.) and its solubility (water soluble or water insoluble).

       

    4. Observe the results of the three "contamination" plates and note the differences in colony appearances.

    5. Observe the demonstration plates of chromogenic bacteria and state the color and water-solubility of each pigment.

    organism
    Color
    Solubility

    Micrococcus luteus

    Mluteus_pig_col.jpg

    Note yellow, water insoluble pigment.

       

    Micrococcus roseus

    mrinsol_yr06.jpg

    Note pink rose, water insoluble pigment.

       

    Mycobacterium phlei

    MPhlei_pig.jpg

    Note orange, water insoluble pigment.

       

    Serratia marcescens

    pigmemtsm.JPG

    Note red, water insoluble pigment.

       

    Staphylococcus aureus

    pigmentsa_zydo.JPG

    Note gold, water insoluble pigment.

       

    Pseudomonas aeruginosa

    Pseud_pig_02_9f39.jpg

    Note green, water soluble pigment.

    Pseudomonas aeruginosa

    pigmentpalight.JPG

    Note light green, water soluble pigment.

       

    Contributors and Attributions

    • Dr. Gary Kaiser (COMMUNITY COLLEGE OF BALTIMORE COUNTY, CATONSVILLE CAMPUS)


    2.9: Results is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

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