Section outline


  • A strip with bubbles containing liquids. DNPG is clear. ADH is pink. LDC is yellow, ODC is yellow. Cit is green. H2S is clear

    A multiplexed biochemical test such as API 20 E is shown. The API 20NE test strip is used to identify specific strains of gram-negative bacteria outside the Enterobacteriaceae. Here is an API 20NE test strip result for Photobacterium damselae ssp. piscicida. (Source of Image: Figure 8.18, OpenStax Microbiology, CC BY License)

    Biochemical testing is based on the fact that microbes have microbial metabolism  involving microbial biochemistry. Different microbes have different metabolic capabilities. Biochemical testing can therefore be used to characterize an unknown microbe and figure out the identity of the microbes. Characterizing and identifying an unknown microbe based on biochemical testing is not only an intellectual exercise for a microbiologist. Characterizing and identifying an unknown microbe based on biochemical testing is in healthcare a critical task to determine the identity of the pathogen causing illness in the patient and finding the appropriate therapeutic intervention. Biochemical tests for fermentation, gelatin hydrolysis, starch hydrolysis, casein hydrolysis, urea hydrolysis, citrate utilization, catalase activity, tryptophane hydrolysis are some examples.




    Upon completion of this module, you will be able to:

    1. Obj. 1 Be able to perform the following biochemical tests and understand how they work: carbohydrate fermentation, gelatin hydrolysis, starch hydrolysis, casein hydrolysis, urea hydrolysis, citrate utilization, catalase activity, tryptophan hydrolysis (indole test). (C.O. # 4 Identify unknown bacteria using various physiological tests.)
    2. Obj. 2 Be able to relate the results of the tests performed to the different types of metabolic activities carried out by individual bacterial species. (C.O. # 4 Identify unknown bacteria using various physiological tests.)
     

    To achieve these objectives: [Edit these items to match your resources and activities.]

    1. Read the Module # Introduction 
    2. Read and view the materials in the Module “LAB 10: BIOCHEMICAL TESTING” in the Pressbooks book. It shows commonly used biochemical tests for fermentation, gelatin hydrolysis, starch hydrolysis, casein hydrolysis, urea hydrolysis, citrate utilization, catalase activity, tryptophane hydrolysis.
    3. Read Chapter # in Textbook Title, Article Title, etc. [Include all reading assignments here that are outside of Moodle. Be as concise as possible. More information can be included in the third-party section below, if necessary.]
    4. Complete the following specific activities in the module:  
        1. Download and read the lecture slides about fermentation (file fermentation v08)
        2. Take the quiz about fermentation.
        3. Download and read the lecture slides about hydrolytic and degradative enzymes (file Hydrolytic _degradative enzymes v09b)
        4. Take the quiz about hydrolytic and degradative enzymes (Hydrolysis)
        5. Download and read the lecture slides about urea – hydrolytic reactions (file hydrolytic reactions - urea v02b)
        6. Take the quiz about urease
        7. Download and read the lecture slides about catalase and oxidase test (file biooxidation & respiration v09b)
        8. Take the quiz about catalase and oxidase test
        9. The instructor will determine which lab test you will actually conducting in the lab from the book Module “LAB 10: BIOCHEMICAL TESTING”
        10. Assignment: Upload the lab report of the actual assigned lab test that your instructor assigned you to perform.

    Module Pressbooks Resources and Activities

    You will find the following resources and activities in this module at the Pressbooks website. Click on the links below to access or complete each item.

    • Lab 10: Biochemical Testing URL
      Students must
      Mark as done
    • Module # Discussion Forum
      Students must
      Mark as done
    • Module # Assignment
      Students must
      Mark as done
    • lecture slides about fermentation (file fermentation v08)

      Dear students,

      please download and read the lecture slides about fermentation (file fermentation v08)

    • lecture slides about urea – hydrolytic reactions (file hydrolytic reactions - urea v02b)

      Dear students,

      please download and read the lecture slides about urea – hydrolytic reactions (file hydrolytic reactions - urea v02b)

    • lecture slides about hydrolytic and degradative enzymes (Casease, Amylase, Tryptophanase) (file Hydrolytic _degradative enzymes v09b)

      Dear students,

      please download and read the lecture slides about hydrolytic and degradative enzymes (file Hydrolytic _degradative enzymes v09b).

    • Lecture slides about biooxidation & respiration v09b (catalase & oxidase) File

      Dear students,

      please download and read the lecture slides about catalase and oxidase test (file biooxidation & respiration v09b)

    • quiz about fermentation

      Dear students,

      the quiz is aligned with 

      1. Obj. 1 Be able to perform the following biochemical tests and understand how they work: carbohydrate fermentation, gelatin hydrolysis, starch hydrolysis, casein hydrolysis, urea hydrolysis, citrate utilization, catalase activity, tryptophan hydrolysis (indole test). (C.O. # 4 Identify unknown bacteria using various physiological tests.)
      2. Obj. 2 Be able to relate the results of the tests performed to the different types of metabolic activities carried out by individual bacterial species. (C.O. # 4 Identify unknown bacteria using various physiological tests.)


      please take quiz/assignment during dates of availability:

      Dates of availability: xx/xx/202x to xx/xx/202x

      Attempts: unlimited within dates of availability.

      Grade/score: Highest score of attempt counts.

      Length of time per attempt: You have xxx minutes for each attempt.

      Uninterrupted attempts required.

      Number of questions: There are 14 questions.

      Contribution towards final grade: yes/no

      The quiz has to be taken in the learning management system, in this case canvas or moodle.

      Email, paper, or any other type of submissions will not be accepted.

       

       

      Sincerely,

      Your Instructor

    • quiz about hydrolytic and degradative enzymes (Hydrolysis, catalase, amylase, tryptophanase))

      Dear students,

      the quiz is aligned with 

      1. Obj. 1 Be able to perform the following biochemical tests and understand how they work: carbohydrate fermentation, gelatin hydrolysis, starch hydrolysis, casein hydrolysis, urea hydrolysis, citrate utilization, catalase activity, tryptophan hydrolysis (indole test). (C.O. # 4 Identify unknown bacteria using various physiological tests.)
      2. Obj. 2 Be able to relate the results of the tests performed to the different types of metabolic activities carried out by individual bacterial species. (C.O. # 4 Identify unknown bacteria using various physiological tests.)

      please take quiz/assignment during dates of availability:

      Dates of availability: xx/xx/202x to xx/xx/202x

      Attempts: unlimited within dates of availability.

      Grade/score: Highest score of attempt counts.

      Length of time per attempt: You have xxx minutes for each attempt.

      Uninterrupted attempts required.

      Number of questions: There are 18 questions.

      Contribution towards final grade: yes/no

      The quiz has to be taken in the learning management system, in this case canvas or moodle.

      Email, paper, or any other type of submissions will not be accepted.

       

       

      Sincerely,

      Your instructor

    • quiz about urease

      Dear students,

      the quiz is aligned with 

      1. Obj. 1 Be able to perform the following biochemical tests and understand how they work: carbohydrate fermentation, gelatin hydrolysis, starch hydrolysis, casein hydrolysis, urea hydrolysis, citrate utilization, catalase activity, tryptophan hydrolysis (indole test). (C.O. # 4 Identify unknown bacteria using various physiological tests.)
      2. Obj. 2 Be able to relate the results of the tests performed to the different types of metabolic activities carried out by individual bacterial species. (C.O. # 4 Identify unknown bacteria using various physiological tests.)

      please take quiz/assignment during dates of availability:

      Dates of availability: xx/xx/202x to xx/xx/202x

      Attempts: unlimited within dates of availability.

      Grade/score: Highest score of attempt counts.

      Length of time per attempt: You have xxx minutes for each attempt.

      Uninterrupted attempts required.

      Number of questions: There are 16 questions.

      Contribution towards final grade: yes/no

      The quiz has to be taken in the learning management system, in this case canvas or moodle.

      Email, paper, or any other type of submissions will not be accepted.

       

       

      Sincerely,

      Your instructor

    • quiz about catalase and oxidase test

      Dear students,

      the quiz is aligned with 

      1. Obj. 1 Be able to perform the following biochemical tests and understand how they work: carbohydrate fermentation, gelatin hydrolysis, starch hydrolysis, casein hydrolysis, urea hydrolysis, citrate utilization, catalase activity, tryptophan hydrolysis (indole test). (C.O. # 4 Identify unknown bacteria using various physiological tests.)
      2. Obj. 2 Be able to relate the results of the tests performed to the different types of metabolic activities carried out by individual bacterial species. (C.O. # 4 Identify unknown bacteria using various physiological tests.)

      please take quiz/assignment during dates of availability:

      Dates of availability: xx/xx/202x to xx/xx/202x

      Attempts: unlimited within dates of availability.

      Grade/score: Highest score of attempt counts.

      Length of time per attempt: You have xxx minutes for each attempt.

      Uninterrupted attempts required.

      Number of questions: There are 8 questions.

      Contribution towards final grade: yes/no

      The quiz has to be taken in the learning management system, in this case canvas or moodle.

      Email, paper, or any other type of submissions will not be accepted.

       

       

      Sincerely,

      Your instructore

    • Assignment: Upload the lab report of lab test
      Opened: Tuesday, December 23, 2025, 12:00 AM
      Due: Tuesday, December 30, 2025, 12:00 AM

      Dear student,

      the assignment is aligned with:

      1. Obj. 1 Be able to perform the following biochemical tests and understand how they work: carbohydrate fermentation, gelatin hydrolysis, starch hydrolysis, casein hydrolysis, urea hydrolysis, citrate utilization, catalase activity, tryptophan hydrolysis (indole test). (C.O. # 4 Identify unknown bacteria using various physiological tests.)
      2. Obj. 2 Be able to relate the results of the tests performed to the different types of metabolic activities carried out by individual bacterial species. (C.O. # 4 Identify unknown bacteria using various physiological tests.)


      Assignment: Upload the lab report of the actual assigned lab test that your instructor assigned you to perform (to be announced).

      The instructor will determine which lab test you will actually conducting in the lab from the book Module “LAB 10: BIOCHEMICAL TESTING”

      Upload the lab report of the actual assigned lab test that your instructor assigned you to perform.

      The structure of the lab report depends on requirements of the instructor.

      Motivation:

      Motivation for the lab report is that students experience and demonstrate the skills 1) to apply the scientific method, 2) apply standard techniques in microbiology, 3) process and understand the underlying theoretical concepts of microbiology.

       

      Instruction:

      One format for a lab report is to report the 1) title of the experiment or test, 2) the hypothesis or research question of the experiment or test, 3) the prediction, 4) the procedure, 5) the results, and 6) the conclusion.

       

      Example of a lab report -

      1) title of the experiment or test: Catalase test

      2) the hypothesis or research question of the experiment or test: It is hypothesized that the bacteria to be tested will be catalase positive OR the research question studied is whether or not the tested bacteria are calatase positive

      3) the prediction: If the bacteria are catalase positive, then formation of bubbles will be observed during the test

      4) the procedure: Transfer bacteria of interest onto microscopic slide using aseptic techniques. Apply enough droplets of 3% hydrogen peroxide solution, so that microbes are covered. Observe microbes in 3% hydrogen peroxide solution for 1 to 3 minutes for the formation of bubbles. Document the results. In parallel, include a positive control of a known lab strain that is positive for catalase

      5) the results:

      The bacteria of interest did/ did not form bubbles (circle appropriate result).

      The positive control did/did not form bubbles (circle appropriate result).

      Include photos if available.

      6) the conclusion:

      The positive control did/did not work , because the bubbles were/were not formed (circle appropriate result). Therefore, the test reagents and the test itself is/is not working properly (circle appropriate result).

      The unknown/bacteria of interest are/are not catalase positive, because the bacteria did/did not form bubbles (circle appropriate result). The results do/don’t support the hypothesis (circle appropriate result).

      You can upload your report as a file, or write by hand on a piece of paper and upload a photo of your handwritten report.



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