Laboratory Investigations in Microbiology

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Chapter 32: Lab Practicum

Because Microbiology is a lab-intensive course, and because you should be able to remember and identify important laboratory tests and procedures, you will be required to take a lab practicum in this course. Rather than looking merely at the academic knowledge of microbiology, the practicum will ask you to interpret actual laboratory results and identify key materials, equipment, and reactions. You will also need to understand the biological basis for many of the tests we have conducted.

The lab practicum will have 30 stations placed around the lab. Each station will feature a microbial culture medium, microscope or other equipment. As you enter, you will receive your question & answer sheet. Your starting point for the practicum will be the station number that is written in the upper right-hand corner of your practicum sheet. Stations 1 - 4 are in the front of the room, 5 - 8 in the second row, and so on until you reach stations 21 - 24 in the last row of lab seats. Stations 25 - 30 are on the side or front of the lab. Please proceed directly and quietly to your assigned station when you enter. As soon as everyone is at their stations, the practicum will begin. You will have one minute at each station, after which you will be asked to rotate to the next-higher number. You cannot go back to a station you have already been at. You cannot take more time than is allotted to you (you will be holding up someone else if you do). Students that refuse to follow these rules will be asked for their answer sheet immediately.

Each station will typically have a two-part question. A) Identify something B) What is the meaning/how does it work? Read each question carefully. There will be 30 questions in all (several of which include BONUS points). Since each question is worth only 1 point, do not worry if you have to skip a question. You may have time left later during the practicum to answer the question, especially if you make yourself a little note in the margin (e.g. "the slant was blue"). This may help you remember later that you meant to say "citrate-positive". 

Questions for the lab practicum may include any or all of the following:

  1. Parts of the microscope
  2. Gram stain
  3. Other kinds of stains (simple, negative)
  4. Other types of microscopes (darkfield, phase contrast)
  5. Parts of the bacterial cell (flagella, capsules, endospores)
  6. Types of culture media (broth, slant, deep, plate)
  7. Types of pipettes
  8. Streak plates vs. spread plates vs. pour plates
  9. Colonies
  10. Bacterial growth curve
  11. Spectrophotometer
  12. Effect of environment: pH, temperature, salt
  13. Contamination
  14. Size of microbes
  15. Types of microorganisms (bacteria, archaea, protozoa, algae, fungi)
  16. Starch hydrolysis 
  17. DNA hydrolysis 
  18. Gelatin hydrolysis 
  19. Casein hydrolysis 
  20. Fermentation reactions (glucose, lactose, sucrose)
  21. Fermentation products (acids, gases); base production
  22. Citrate use
  23. SIM deeps (H2S, Indole, motility)
  24. Motility deeps
  25. Catalase
  26. Anaerobic growth chamber
  27. Oxidase
  28. Nitrate reduction
  29. Urease
  30. Methyl red/Voges Proskauer
  31. Coagulase
  32. Antibiotics
  33. Dichotomous key

Practice questions (with links to answers) are available here.


© 2003 - 2015 Josť de Ondarza, Ph.D.