Hydrogen Sulfide Test – Principle, Procedure, Uses, And Interpretation

There are a number of organisms that have the ability to reduce compounds that contain sulfur down to hydrogen sulfide during the process of metabolism – and this can be a real issue.

Hydrogen Sulfide Test - Principle, Procedure, Uses, And Interpretation

Hydrogen sulfide is a gas that has the potential to be incredibly harmful to individuals, and it is important that scientists have the ability to detect and discover this using a simple procedure.

Read on to learn all you need to know about the hydrogen sulfide test, including how it works, how sulfide is detected, and the implications of this.

What Is Hydrogen Sulfide?

Hydrogen sulfide (H2S) is a colorless gas that contains a very pungent odor, which has been compared to the smell of rotten eggs.

In addition to its offensive smell, H2S is also poisonous, corrosive, and highly flammable, and can cause severe burns.

Hydrogen sulfide is produced by the microbial breakdown of a particular organic matter in an environment that lacks oxygen.

Also known as anaerobic digestion, the process also occurs via bacteria in our digestive system, as well as certain species of fungi, worms, plants, and animals.

It is also created when sulfur-containing chemicals react with water or other substances.

The chemical reaction between these two elements creates an acid called hydrocyanic acid, which then reacts further to form hydrogen sulfide.

The amount of hydrogen sulfide released into the air depends upon the type of organism involved, the temperature of the surroundings, the pH level of the surrounding area, and the concentration of dissolved oxygen in the water.

How Does Hydrogen Sulfide Get Into The Body?

When hydrogen sulfide enters your body, it will enter through your nose, mouth, eyes, skin, lungs, stomach, intestines, kidneys, bladder, liver, blood vessels, muscles, bones, joints, nerves, brain, heart, and any other organ or tissue where there is a high concentration of blood flow.

This means that if you are exposed to high levels of hydrogen sulfide for long periods of time, you could potentially become seriously ill.

If you are planning to take part in activities such as diving, deep-sea fishing, scuba diving, or snorkeling, then you should ensure that you wear protective equipment before entering the water.

This includes breathing apparatus, masks, gloves, goggles, and ear plugs.

You should also make sure that you do not eat anything while underwater, and that you drink plenty of fluids.

If you are working in an environment that contains large amounts of hydrogen sulfide, you should wear appropriate safety clothing, such as rubber suits, boots, gloves, and eye protection.

What Is The Principle Of A Hydrogen Sulfide Test?

What Is The Principle Of A Hydrogen Sulfide Test?

The principle of the hydrogen sulfide test is to measure the presence of hydrogen sulfide in an organism, and can also detect members of the Enterobacteriaceae family.

Some bacteria produce hydrogen sulfide as a waste product, so they must expel it from their bodies.

If you want to find out whether or not a member of the Enterobacteriaceae family is present, then you can use the hydrogen sulfide test.

Here, both a sulfur compound and an iron compound are tested in order to test for the presence of the hydrogen sulfide gas – in the event that the sulfur compound is reduced by the strain of bacteria, hydrogen sulfide will be produced, and this will indicate whether or not the microbe in question reduces compounds containing sulfur to sulfides during the metabolic process.

Hydrogen sulfide itself is created when specific bacteria reduce sulfur, and this sulfur contains key amino acids such as methionine or cysteine.

It can also be produced through the reduction of inorganic sulfur compounds – these include sulfates, thiosulfates, and sulfites – during the process of protein degradation or anaerobic respiration, as both of these processes move the electrons to sulfur, rather than to oxygen.

If these processes occur, then a compound of hydrogen sulfide gas is produced, and this will, in turn, react with iron compounds.

The end result will be the black precipitate known as ferric sulfide – if this is black, then it is an indication that hydrogen sulfide is present.

In many cases, the presence of hydrogen sulfide is used to identify a particular organism that is known to carry out this process.

What Is The Procedure Of A Hydrogen Sulfide Test?

When carrying out a hydrogen sulfide test, there are a number of mediums that may be used – the key is to ensure that they contain iron compounds.

Triple sugar iron agar (TSIA) is a popular option; this can also be used to detect the ability of microbes to ferment sugars.

The test is performed by taking an inoculum from a pure culture and transferring this to a sterile TSIA slant.

This tube is then incubated at between 35 and 37 degrees C for 24 hours and then removed to analyze the results.

The iron ions in the TSIA will have a strong affinity for any sulfide ions that may be present, and the latter will combine with the former to create a black compound – this is known as ferrous sulfide (FeS).

If the agar turns black, then this indicates that hydrogen sulfide is present in the microbe.

Results are determined through observation of the agar, and this can also offer other information.

For example, a crack in the agar indicates that the fermentation of sugars is occurring and that gas is being produced, while the agar turning yellow shows that at least one of these sugars is producing acid.

Final Thoughts

Discovering the presence of hydrogen sulfide is important for several reasons: it can be used to identify some strains of bacteria that produce this substance and can help scientists to identify particular microbes and organisms.

Fortunately, this is a test that is fast, easy, and effective, so should be on any microbiologist’s skill list!

Jennifer Dawkins

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