Microbiology Biochemical Tests Quiz

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What does a positive result for the indole test indicate?

Production of acetoin
Ability to utilize citrate
Tryptophanase activity (correct)
Mixed acid fermentation

Which of the following tests results in a pink/red color upon a positive reaction?

Starch hydrolysis test
Citrate utilization test
Voges-Proskauer test (correct)
Methyl red test

What color indicates a positive result for citrate utilization?

Red
Blue (correct)
Pink
Clear

Which test would show a clear zone around bacterial growth after iodine is added?

Starch hydrolysis (C) Signup and view all the answers

In the methyl red test, a positive result is indicated by which color change?

Red (B) Signup and view all the answers

Which of the following tests confirms hydrogen sulfide production?

Black precipitate in the medium (A) Signup and view all the answers

What indicates a positive reaction for urease activity?

Pink color (A) Signup and view all the answers

Which reaction produces a green color after adding ferric chloride?

Phenylalanine deamination (C) Signup and view all the answers

What result would you expect from a positive catalase test?

Bubbling (B) Signup and view all the answers

Which test is used to determine if an organism can utilize citrate as its sole carbon source?

Citrate utilization test (B) Signup and view all the answers

Which organism is indicated by positive results in the methyl red and indole tests?

Escherichia coli (A) Signup and view all the answers

What indicates a positive result for the Voges-Proskauer test?

Pink/red color after adding VP reagents (C) Signup and view all the answers

What does a red layer after adding Kovac's reagent indicate in the indole test?

Tryptophanase activity (C) Signup and view all the answers

Which of the following tests reveals a clear zone around bacterial growth after iodine is added?

Starch hydrolysis test (A) Signup and view all the answers

Which color change is associated with a positive reaction for urea hydrolysis?

Pink (A) Signup and view all the answers

In which test would you expect to see a purple color within seconds?

Oxidase test (C) Signup and view all the answers

What result indicates black precipitate formation in the medium?

Hydrogen sulfide production (D) Signup and view all the answers

What is indicated by a clear zone around growth on spirit blue agar?

Fat hydrolysis (B) Signup and view all the answers

What color indicates a positive reaction in the methyl red test?

Red (B) Signup and view all the answers

Which test discriminates between Escherichia coli and Enterobacter aerogenes?

Methyl red test (D) Signup and view all the answers

In the Voges-Proskauer test, what color indicates a positive result?

Pink (C) Signup and view all the answers

What is the indicative result for the citrate utilization test?

Blue color (A) Signup and view all the answers

Which of the following is a result from a positive catalase test?

Bubbling (B) Signup and view all the answers

What do you expect to see in a positive indole test?

Red layer (C) Signup and view all the answers

A positive hydrogen sulfide production test is indicated by which result?

Black precipitate (D) Signup and view all the answers

Which of these tests shows positive results with a clear zone around bacterial growth after specific reagent application?

Starch hydrolysis (D) Signup and view all the answers

Which test distinguishes Enterobacter aerogenes from Escherichia coli based on its ability to produce acetoin?

Voges-Proskauer test (A) Signup and view all the answers

IMViC Tests

A group of four biochemical tests used to differentiate among gram-negative bacilli. They identify bacteria based on their metabolic pathways.

Indole Test

Test for tryptophanase activity; a positive result is formation of a red layer after adding Kovac's reagent