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
If fermentation occurs on Mannitol Salt Agar, what color is the indicator?
yellow
Phenol red pH indicator
yellow for acid and fuchsia pink for basic
differential
uses glucose, sucrose, and lactose
Eosin Methylene Blue
differential and selective medium
the differential indicator dyes are eosin Y and methylene blue
If fermentation occurs on EMB agar, what color is it?
large amounts of acid are green and small amounts are pink
What two gram negative bacterias grow on EMB?
E coli and pseudomonas aeruginosa (no lactose)
Citrate test
detect the ability of certain bacteria to utilize citrate as the sole source of carbon
-the indicator is bromothymol blue
If citrate is used, what color does the indicator turn if alkali is used)
blue
If citrate and acid is used, what color does the indicator turn?
yellow
What color indicates citrate negative?
green
Fermentation tubes
ability to ferment a specific sugar is dependent on enzymes and F tube use phenol red detect gas production
Starch test
differential
iodine is the indicator
fermentation
the incomplete break down of substrates
In phenol red, what does red broth and no bubble indicate?
no fermentation, no acid
-/-
In phenol red, what does yellow broth with a bubble?
A/G
acid and gas production
In Simmons Citrate Agar, what does green agar indicate?
-
citrate is not utilized
In Simmons Citrate Agar, what does blue agar indicate?
+
citrate is utilized
In Triple Sugar Iron, what does an alkaline slant and acid butt indicate?
K/A
bacteria ferments glucose
In TSI, what does an acid slant, acid butt, and gas production indicate?
A/A, G
bacteria ferments glucose, sucrose, lactose and making acid
In TSI, what does an alkaline slant, acid butt, and H2S production?
K/A, H2S
bacteria ferments glucose and makes acid
hydrogen sulfide is also formed
