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14.2: Lab Reports

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    General Guidelines

    1. Lab reports must be typewritten—no handwritten reports will be accepted! Font size should be no larger than 11 or 12. The lab report format is described below.

    2. While writing your lab report, please remember that everything must be in your own words. There is a no tolerance policy on plagiarism. Your instructors can Google along with the best of you. If they find that segments of your lab report are copied word-for-word from another source (e.g., from the web, your lab handouts or text book), you will receive a 0 for that lab report. If they find that lab reports from different people are word-for-word copies, all involved will receive a 0 for their lab reports.

    3. Approximate length. The lab report should be at least 2 pages of text (not including figures, tables, pictures and references)

    4. Make sure to include the original, graded sheets of the following items:

    a. Gram stain results

    b. Dichotomous key/required media

    c. Metabolic test results (These can be placed at the end of the lab report if you want to make neater, corrected copies for your lab report.)

    Lab Report Format


    You should have an appropriate title for your lab report. Include on your title page: your name, your instructor’s name, and your class section.

    Your lab report should be divided into the sections listed below. Pay careful attention to what material belongs in each section. Each of the sections should be labeled in the lab report.


    In this section you should discuss the importance of bacterial identification procedures. This section should also include general background information about the use of the Gram stain and metabolic tests to identify bacteria and you should discuss why staining procedures alone are not sufficient for bacterial identification. (2-3 paragraphs)


    In this section, you should explain the steps followed to identify your unknowns. For the Gram stain procedure, you may simply reference the lab manual, unless you have deviated from the protocol (if you do anything different from the instructions, you should explain that here). This section should also include the dichotomous key that you used to set up your experiments, and you should describe the rationale that led you to the formation of this key. You should also describe each metabolic test you used (name the medium, describe the inoculation procedure, describe any procedures necessary post-inoculation and explain what metabolic process you are testing for). (3-4 paragraphs)


    This section will be used to present your results for the Gram stain and the metabolic tests. Divide this section into 2 parts: 1 part for each of your unknowns.


    Unknown 1A

    Gram stain results. Describe color, Gram reaction, morphology and arrangement. Include either a photograph or a color drawing here. Students can use the microscope at the instructor’s desk to take a picture, which can then be saved to a flash drive and printed out to be added to the lab report. The photograph added to the lab report should be in color. If you make a drawing, it must also be in color, and make sure that the bacteria’s morphology and characteristic arrangement (if any) can be seen. Drawings/photographs should be labeled. You should include the table that you filled out in Lab 5, but you must also describe your Gram staining results in the body of your lab report.

    Metabolic Test results. You should include the table you filled out in Lab 8, but you must also summarize your results in the body of the lab report. You need to describe the results (colors, bubbles, etc.), make a determination as to whether the result is a positive or a negative result, and then interpret the result. For example: “After inoculation my urea slant turned pink. This was a positive result, indicating that this bacteria produces a urease.”

    Unknown 1B

    (as above for Unknown 1A) (1-2 paragraphs for each unknown, not including the tables.)


    It is here where you will make your identification of your unknowns based on the results of the Gram stain and the metabolic tests. Divide it into 2 sections, 1 for each unknown. Describe in words and sentences your rationale for making your final identifications. If you have any problems or inconsistencies with your experiments (ex: an incorrect result for your gram stain or a metabolic test result that is not consistent with your bacterial identification), you should discuss them here. Try to explain what might have happened to give you an incorrect result.

    Also include in this section an additional test that would confirm your results for each unknown. This is a test that you did not perform; it could be a staining procedure or an additional metabolic assay. Make sure you mention the expected result for these additional tests.

    After you have discussed the identification of your unknowns, include 1-2 paragraphs about each of your identified bacteria. This section should include what your test results tell you about the bacteria’s structure, morphology, and metabolism. Also add some general information about the bacteria, including any diseases that this species has been shown to cause. You can use your textbook to obtain this information, or use the following websites:

    • CENTERS FOR DISEASE CONTROL AND PREVENTION: Contains information about infectious diseases, their causes, treatments, epidemiology and prevention.
    • AMERICAN SOCIETY FOR MICROBIOLOGY: allows for searches of their journals; also contains links to current information about Microbiology and Microbiology education.
    • NATIONAL LIBRARY OF MEDICINE, part of the National Institutes of Health; includes information on infectious diseases; search engine can be used to find current information on a particular topic
    • CELLS ALIVE: links to information about bacteria, viruses and eukaryotic pathogens


    The Lab Report will be due on Lab 10. Lab reports that are turned in late will have 5 points deducted for each day they are late. No reports will be accepted after lab 11—no exceptions!

    Suggestions for writing a good lab report:

    1. Have someone proofread your lab report before you turn it in.

    2. Use the grading rubric for the lab report (see below) as a checklist to make sure that you formatted the lab report correctly, and that you have all the required information.

    3. The Campus Writing Center is located in the Library (L-118). You can visit them for additional help with your writing.

    14.2: Lab Reports is shared under a CC BY-NC-SA license and was authored, remixed, and/or curated by Joan Petersen & Susan McLaughlin.

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