TSIA Lab Overview Flashcards

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Questions and Answers

What type of medium is the Triple-Sugar Iron Agar (TSIA)?

Differential medium.

The Triple-Sugar Iron Agar medium tests for what?

An organism's ability to ferment selected carbohydrates and to produce hydrogen sulfide (H2S).

What does the TSIA medium contain?

3 sugars, a pH indicator (phenol red), two sources of sulfur (cysteine & thiosulfate), an iron salt, and a general nutrient base (peptone, yeast extract).

Match the sugars in TSIA to their concentrations:

Glucose = (0.1%) Sucrose = (1%) Lactose = (1%) Signup and view all the answers

What color is phenol red at neutral pH values?

Red. Signup and view all the answers

What color is phenol red under acidic conditions?

Yellow. Signup and view all the answers

What color is phenol red under alkaline conditions?

Bright red/bright fuchsia red. Signup and view all the answers

What are the two sources of sulfur in a TSIA medium?

Cysteine and thiosulfate. Signup and view all the answers

What is the role of iron salt in the TSIA medium?

To detect the production of hydrogen sulfide gas (H2S). Signup and view all the answers

Color reactions in the medium allow you to differentiate between what?

Organisms that utilize only glucose, glucose and another sugar, or only peptone. Signup and view all the answers

It is possible to determine if the organism uses sucrose or lactose, but not which of these sugars specifically.

False Signup and view all the answers

How is the TSIA medium inoculated?

By stabbing into the butt with an inoculating needle and then streaking down the surface of the slant. Signup and view all the answers

How long should TSIA slants be incubated?

24 hours. Signup and view all the answers

What are the components of TSIA results?

The color reaction of the slant, the color reaction of the butt, the production of hydrogen sulfide, and the production of gas. Signup and view all the answers

If an organism can metabolize glucose and another sugar, what will be the color of the slant and butt?

Both will be yellow (acid reaction). Signup and view all the answers

In TSIA, an acid reaction is when?

Both slant and butt are yellow. Signup and view all the answers

If the organism can use only glucose, what will be the color of the butt and slant?

The butt will be yellow and the slant will be bright red. Signup and view all the answers

What do organisms that do not use any of the sugars in the medium do?

Catabolize proteins. Signup and view all the answers

Protein catabolism and deamination of amino acids release what?

Ammonia. Signup and view all the answers

Some organisms utilize sulfur compounds as what?

Electron acceptors under oxygen limiting conditions. Signup and view all the answers

Hydrogen sulfide is associated with what smell?

The smell of rotten eggs. Signup and view all the answers

Hydrogen sulfide gas is invisible.

False Signup and view all the answers

What functions to detect the production of hydrogen sulfide in the TSIA medium?

An iron salt. Signup and view all the answers

The iron salt reacts with hydrogen sulfide to produce what?

Iron sulfide. Signup and view all the answers

The result of iron salt plus hydrogen sulfide is what?

Iron sulfide (is visible). Signup and view all the answers

Iron sulfide is visible as what in the medium?

Black precipitate. Signup and view all the answers

If the black precipitate is present, then the organism is classified as what?

Hydrogen sulfide positive or H2S positive. Signup and view all the answers

What do the results K, A, and G indicate in TSIA interpretation?

Alkaline (K), Acid (A), Gas (G). Signup and view all the answers

Interpret the results of (K/A) or (Red/Yellow).

Glucose fermentation plus or minus peptone catabolism. Signup and view all the answers

If TSIA results are Red/Yellow, then the abbreviation will be?

K/A. Signup and view all the answers

What does K/A, G indicate in TSIA results?

Glucose fermentation; gas produced plus or minus peptone catabolism. Signup and view all the answers

What is indicated from results showing an acid butt and alkaline slant?

Only glucose was fermented. Signup and view all the answers

What do TSIA results include?

The color reaction of the butt, the color reaction of the slant, the production of hydrogen sulfide, and the production of gas. Signup and view all the answers

What are the materials needed for the TSIA procedure?

Inoculating loop, inoculating needle, and 4 tubes of Triple-Sugar Iron Agar. Signup and view all the answers

Study Notes

TSIA Overview

Triple-Sugar Iron Agar (TSIA) is a differential medium used in microbiology.
It assesses an organism's ability to ferment selected carbohydrates and produce hydrogen sulfide (H2S).

Composition of TSIA

Contains 3 sugars: 0.1% Glucose, 1% Sucrose, and 1% Lactose.
Includes a pH indicator (phenol red) to visualize pH changes.
Has two sulfur sources: cysteine (a sulfur-containing amino acid) and thiosulfate (S2O32-).
Incorporates an iron salt and a general nutrient base (peptone, yeast extract).

pH Indicator Reactions

Phenol red colors:
- Red at neutral pH.
- Yellow under acidic conditions.
- Bright red under alkaline conditions.

Function of Iron Salt

Iron salt is critical for detecting hydrogen sulfide production.
Reacts with hydrogen sulfide to form iron sulfide, which appears as a black precipitate in the medium.

Interpretation of Results

Results assess the color reaction of the slant and butt, and the production of hydrogen sulfide and gas.
Common result interpretations:
- (A/A): Both slant and butt turn yellow from acid reactions indicating that both glucose and another sugar are fermented.
- (K/A): The slant remains red (alkaline) and the butt turns yellow (acid), showing that only glucose was fermented.
- (K/K): Both slant and butt remain alkaline indicating protein catabolism.

Gas Production

Bubbles in the medium can be indicated by the notation G, showing gas production during fermentation.

Additional Notes

Prolonged incubation beyond 24 hours can lead to reversion, yielding inconclusive results.
If an organism does not utilize any of the sugars, it may catabolize proteins, producing ammonia, resulting in a bright red appearance (alkaline).
Hydrogen sulfide is associated with the rotten egg smell and is invisible in its gas form.

Practical Procedure

TSIA inoculation involves stabbing the butt and streaking the surface of the slant with an inoculating needle, followed by incubation.

Summary of Common Results

Acid Butt and Alkaline Slant (K/A): Only glucose was fermented.
Acid Butt and Acid Slant (A/A): Both glucose plus another sugar (lactose or sucrose) were fermented.
Black Precipitate: Indicates hydrogen sulfide production, confirming organism classification as H2S positive.

Required Materials

Inoculating loop, inoculating needle, and 4 tubes of Triple-Sugar Iron Agar for the TSIA procedure.

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Description

Explore the essential concepts of the Triple-Sugar Iron Agar (TSIA) in this set of flashcards. Learn about its differential medium nature, carbohydrate fermentation capabilities, and sulfur sources. Perfect for microbiology students looking to reinforce their understanding of this critical lab component.