Consider a culture medium on which only gram-positive organisms such as staphylococcus aureus colonies can grow due to an elevated nacl level. a yellow halo surrounds the growth, indicating the bacterium fermented a sugar in the medium, decreasing the ph as a result and changing the color of a ph indicator chemical. this type of medium would be referred to as a(n)
a. enrichment culture.
b. differential and enrichment culture.
c. selective and differential medium.
d. selective median.
e. differential medium.