Lab Exam 2 Flashcards
The Durham tube inverted in a tube of Phenol Red Broth detects the production of which of the following?
gas
Catalase converts which of the following chemicals to oxygen and water?
hydrogen peroxide
Yellow and no bubble in the Durham tube is an indication of
A/-
acid
The color of phenol red at an acid pH is?
yellow
A growth medium that favors the growth of some microorganisms but inhibits the growth of other microorganisms is a ________________ medium.
selective
solid media
-2% agar
- can see colony morphology, pigmentation, hemolysis
-examples are Nutrient Agar and Trypticase Soy Agar
liquid media
-no agar
-for inoculum preparation
-Examples are nutrient broth, trypticase soy broth
semi-solid medium
.5% agar
motility medium
special purpose media
aids in the isolation and identification of specific microorganisms
selective media
inhibit the growth of one organism and permits the growth of another
-helpful when separating a mixture of gram-positive and gram-negative
differential media
cause an observable color change when a particular chemical reaction occurs
Phenylethyl Alcohol Agar (PEA)
selective media
allows the growth of gram-positive and inhibits the growth of gram-negative
used to isolate staph and strep
MacConkey (MAC)
-selective and differential
-the selective ingredients are bile salts which inhibit gram positive
-differential ingredient is lactose
If fermentation occurs on MAC agar, what color would the indicator be?
pink-red
Mannitol Salt Agar
-selective and differential
-selects for staph
-differential ingredient is sugar mannitol
-7.5% NaCl