BIOD 171 LAB 9 EXAM

BIOD 171 LAB 9 EXAM

Using the observations made and recorded from PL09 Unknown Pathogen, complete the
results sections accordingly.


1. Given Culture A and Culture B were accidentally mixed, what observations were made from the
Gram stain (shown below)?


Gram-positive cocci (spherical) clusters and Gram-negative bacillus (rods) were observed.




2. Given the results from a MacConkey agar plate shown below, what is the shape of Culture A?
Culture B?

MacConkey agar is selective for Gram-negative bacteria. Thus, Culture A must be Gram-
positive as no growth was observed. Coupled to the results of the gram stain, Culture A
(Gram-positive) must be the cocci.

, Culture B must be Gram-negative (growth observed) and this correlates to the bacillus or
rod-shaped bacteria.




3. The hemolytic properties of both cultures were next examined by streaking each culture on a
blood agar plate (shown below). What is the hemolytic status of Culture A? Culture B?


Culture A exhibits beta hemolysis as defined by the region of clearing around the growing
bacterial streak.


Culture B exhibits gamma-hemolysis (non-hemolytic) as indicated by the white colonies
growing on the still red agar.