Microbiology Lab Packet #2
Think of these lab packets as homework for the lab part of the class. They are designed to help prepare you for the departmental lab exams. To answer these questions you will need to use both the lab workbook as well as your text book. In addition to these questions, you will need to turn in the signed data sheets from your workbook.
Describe in great detail the steps in performing a Gram stain. Include incubation times. Deﬁne primary stain and counter stain. In the Gram stain, what dye is primary stain, which is the counter stain?
Special Stains (Capsule Ex. 3.9, Endospore Ex. 3-10, Flagella Ex. 3.12)
Describe in great detail the steps in performing an endospore stain. Include incubation times.
What does it mean to be Gram positive, Gram negative?
Colony Morphology Ex 2.2
Micro lab packet 2
Kirby-Bauer Method Ex 7.3
What is the type of media used in the Kirby-Bauer test and why is it used?
Describe what is observed for a bacteria that is sensitive to antibiotics in a Kirby-Bauer test, and to a bacteria that is not sensitive to antibiotics.
Does the agar have an antibiotic beyond the zone of inhibition?
Is the presence of a clear zone around the disc enough evidence to determine antibiotic resistance?
Micro lab packet 2
Disinfectants Ex 2.14
Which germicide was most effective and at what concentration?
Which was the least effective? Defend your choices.
What purpose did the four controls serve? Be speciﬁc.
Include Completed Data sheets for:
Data Sheet 3-9 (pages 213-214) Sketch capsuled stained bacteria; Questions 1 & 2
Data Sheet 3-10 (pages 219-220) Sketch Endospore Stained bacteria; Questions 1-4
Data Sheet 3-12 (pages 227-228) Sketch Flagella Stained bacteria; Questions 1 & 3
Data Sheet 2-14 (pages 139-140) Questions 1-3
Data Sheet 7-3 (pages 535-536) Questions 1-7
Gram Staining 3.7