5.19: Triple Sugar Iron Agar

Question 1

Which carbohydrate(s) are typically present in TSI agar?

Answer 1

-glucose, lactose, and sucrose

Question 2

If an organism is capable of reducing sulfur and producing hydrogen sulfide, the result that is expected in a TSI agar slant is:

Answer 2

-black precipitate

Question 3

What does a TSI tube with a cracked or lifted agar surface indicate?

Answer 3

-The bacteria produced gas (CO2 and H2).

Question 4

What is the primary purpose of using TSI agar in microbiology?

Answer 4

-To test for carbohydrate fermentation and sulfur reduction

Question 5

In TSI agar, what does a pink color throughout the medium indicate?

Answer 5

-Alkaline conditions

Question 6

Which of the following describes a bacterial strain that ferments glucose but not lactose and sucrose in the TSI test?

Answer 6

-K/A

Question 7

Which of the following statements is true about TSI agar?

Answer 7

-It helps differentiate bacteria based on carbohydrate fermentation and sulfur reduction.

Question 8

What is the role of phenol red in the TSI test?

Answer 8

-it serves as a pH indicator

Question 9

What does the “TSI” in TSI agar stand for?

Answer 9

-triple iron sugar

Question 10

Which of the following describes a bacterial strain that does not ferment glucose but catabolizes aerobically and anaerobically the peptone in the TSI test?

Answer 10

-K/NC

Question 11

If an organism that is incubated on a TSI agar slant produces a red slant and red butt, this indicates that the organism

Answer 11

-Does not ferment either glucose or lactose.

Question 12

What is the purpose of the slant and butt portions in TSI agar?

Answer 12

-To provide different nutrient sources

Question 13

If an organism that is incubated on a TSI agar slant produces a yellow slant and yellow butt, this indicates that the organism

Answer 13

-Ferments both glucose and lactose.

Question 14

In TSI agar, what does a yellow color throughout the medium indicate?

Answer 14

-acidic conditions

Question 15

In TSI agar, what does a red slant and yellow butt indicate?

Answer 15

-The bacteria can ferment glucose but not lactose.

Question 16

the TSI tests for:

Answer 16

-sulfur reduction
-glucose, lactose, and sucrose fermentation

Question 17

The medium is an agar slant with a deep butt, to prove ?? and ?? growth environments

Answer 17

-aerobic
-anaerobic

Question 18

yellow slant=
red slant=

Answer 18

-glucose and lactose/sucrose fermentation
-glucose fermentation and deamination

Question 19

A glucose-only fermenter - lower the pH (acid
products) and turn the entire medium ??

Answer 19

-yellow

Question 20

As the glucose diminishes, ammonia produced
from the deamination of amino acids by organisms
located in the aerobic region (slant) will begin to
raise the pH and turn it ??

Answer 20

-red

Question 21

A TSI with a red slant and yellow butt after a 24-
hour incubation period indicates that the organism
ferments:

Answer 21

–glucose but not lactose and/or sucrose

Question 22

K/A:
K/NC:
K/A,H2S:
A/A:

Answer 22

-alkaline slant/acid butt
-alkaline slant/no change in butt
-alkaline slant/acid butt, hydrogen sulfide present
-acid slant/acid butt