Unknown ID Guidelines 

Late Penalty = (–  1 point) per day per unknown

Each student will receive broth cultures containing 2 unknown bacteria. You will also receive a chart identifying the physical and biochemical traits of all the bacteria used in lab. It will be your task to correctly identify each unknown bacterium using a series of tests. You are also responsible for successfully maintaining a pure culture of each unknown bacterium. At the conclusion of your tests you will hand in your report sheets for the unknowns.

Grading (50 points total)

Complete dichotomous key:                                                    5 points each (10 points total)

Correct identification (per unknown) (First try):                  20 points each

Correct identification (per unknown) (second try):              15 points each

Incorrect identification after second try:                                2 points per correct test result

High-quality digital photo of unknown's Gram stain:        + 1 Bonus each

High-quality digital photo of unknown's colonies:             + 1 Bonus each

Cautions:

1. Some tests may take more than one day 
   • Methyl Red: 5 days
   • Gelatinase: 1 - 2 weeks
   • Citrate: 1 - 3 days
2. Some tests should be evaluated within 24 hours to be accurate:
   • Fermentation (Glu, Lac, Suc)
   • Casein
3. Some tests may give ambiguous results.
   • Methyl Red test: orange color = negative
   • Fermentation: orange = negative
   • Oxidase: dark pink, red, purple or black = positive; also, oxidase results may be ambiguous with pigmented colonies

Hints:

Visit the Library's reference section and look up the description of your unknown bacteria in Bergey's Manual. This will describe the bacteria and mention colony characteristics useful in confirming the identity of your unknown.

Colony characteristics may help in identification. 

Second Chance Policy

• For each unknown incorrectly identified you will be informed which test results were incorrect

• You may continue to do tests as long as you have $$ left

• You can earn 15/20 points if identified correctly on the second try

• If you are incorrect on the second try, you will receive 2 points per correctly performed test for that unknown's ID