SIM Sulfur Biochemical Test Overview

What is the purpose of the SIM Sulfur Test?

To determine if bacteria can produce thiosulfate reductase and cysteine desulferase to break down sodium thiosulfate and cysteine.

What are the substrates used in the SIM Sulfur Test?

Sodium thiosulfate and cysteine.

What enzymes are produced by bacteria in the SIM Sulfur Test?

Thiosulfate reductase and cysteine desulferase.

What does thiosulfate reductase break down?

Sodium thiosulfate to form hydrogen sulfide.

What does cysteine desulferase break down?

Cysteine to form hydrogen sulfide.

What is the indicator used in the SIM Sulfur Test?

Iron.

What reaction occurs when hydrogen sulfide combines with iron?

It produces sulfuric acid and ferrous sulfide.

What is the significance of the black precipitate in the SIM Sulfur Test?

It indicates a positive result, showing that bacteria can produce thiosulfate reductase and cysteine desulferase.

What does a positive result in the SIM Sulfur Test look like?

A black precipitate due to ferrous sulfide.

What indicates a negative result in the SIM Sulfur Test?

No black precipitate, indicating no formation of ferrous sulfide.

What happens when there is no hydrogen sulfide produced in the SIM Sulfur Test?

Iron has nothing to combine with, resulting in no sulfuric acid or ferrous sulfide formation.

What color indicates a positive result in the SIM Sulfur Test?

Black, due to ferrous sulfide.

What color indicates a negative result in the SIM Sulfur Test?

No color change, as there is no formation of ferrous sulfide.

What are the products formed in the SIM Sulfur Test?

Hydrogen sulfide, sulfuric acid, and ferrous sulfide.

What does the presence of hydrogen sulfide indicate in the SIM Sulfur Test?

That the bacteria can break down either sodium thiosulfate or cysteine.

What is the role of sodium thiosulfate in the SIM Sulfur Test?

It serves as a substrate for thiosulfate reductase.

What is the role of cysteine in the SIM Sulfur Test?

It serves as a substrate for cysteine desulferase.

What is the outcome if bacteria cannot produce thiosulfate reductase or cysteine desulferase?

The test will be negative, showing no black precipitate.

How is the black precipitate formed in the SIM Sulfur Test?

By the combination of hydrogen sulfide with iron.

What is the significance of sulfuric acid in the SIM Sulfur Test?

It is produced when hydrogen sulfide combines with iron, contributing to the test's results.