The rotten egg sulfur smell is associated with hydrogen sulfide (H₂S), a colorless gas. The unpleasant odor can arise in water supplies, foods and the human. The stench is driven by various microbial processes of organisms invisible to the eye.
One common source of the rotten egg smell in water is anaerobic bacteria. These remarkable microbes thrive in environments devoid of oxygen, such as stagnant water, groundwater or some sewage systems.
The bacteria consume organic matter and produce hydrogen sulfide (H2S) as a byproduct. H2S forms an important source of metabolic energy for other microorganisms, which feed on it.
Bacteria don't live long, from a few hours to a few weeks. They spend their lives creating more bacteria, and when they perish the nutrients in their bodies return to the ecosystem.
The Microbial Process in Water
The rotten egg smell in water is commonly due to hydrogen sulfide gas. This compound often appears in groundwater, particularly in regions with high organic matter or near sulfur-producing bacteria.
Groundwater can become tainted by sulfate-reducing bacteria (SRB), which thrive in low-oxygen conditions found in deep wells or stagnant water. These bacteria consume sulfate from their environment and convert it into hydrogen sulfide.
This process can sometimes result in concentrations of hydrogen sulfide reaching up to 0.1 parts per million (ppm). At this density the water smells distinctly rank.
Not only does this gas make water unpleasant to drink, it can also cause corrosion of pipes and fixtures. Hydrogen sulfide can cause corrosion rates in pipes to increase by 30% compared to neutral waters.
Microbial Process
Organic Material Decomposition: anaerobic bacteria feed on organic matter present in the water, such as decaying plants, sediments, and waste materials.
Reduction of Sulfate: Certain bacteria, including sulfate-reducing bacteria (SRBs), utilize sulfate (SO₄²⁻) as a terminal electron acceptor during the process of anaerobic respiration. This reduction process converts sulfate into hydrogen sulfide and results in the infamous rotten egg smell.
Conditions Favoring Growth: Warmer temperatures, low pH, and increased organic load can promote the growth of these bacteria, leading to prolific hydrogen sulfide production.
The presence of hydrogen sulfide in water can be troubling but not unusual unless it persists. It's toxic in high concentrations and can indicate the presence of harmful bacteria, making water unsafe. Yet, sulfur has known benefits to the skin.
In the Human Body
The human body can also produce a rotten egg smell due to various biological processes. This happens in the digestive system, where foods and intestinal bacteria interact to create hydrogen sulfide.
The Microbial Process in the Body
Food Digestion: Foods high in protein, such as eggs, meat, and certain vegetables, like cruciferous vegetables (cabbage & mustard families), contain sulfur-containing amino acids including cysteine and methionine.
Digestive Bacteria Activity: When these proteins are broken down, digestive bacteria metabolize the sulfur-containing amino acids, producing hydrogen sulfide as a byproduct.
Flatulence: Hydrogen sulfide can be expelled in flatulence or breath with a noxious odor.
Overgrowth of sulfate-reducing bacteria can raise production of hydrogen sulfide, emerging in foul-smelling farts or belches and burps. Medical conditions, like irritable bowel syndrome (IBS) or infections, can increase production of hydrogen sulfide and create even more odors.
Dysbiosis, an imbalance in digestive system microbiota, can exacerbate this issue. Shifting to a high-protein diet without sufficient fiber can cause a spike in gas odor. To manage this fine stench, eat more fiber-rich foods such as fruits, vegetables whole grains and "probiotics".
In Eggs
Rotten eggs also emit the sulfur smell. Fresh eggs typically don't have a strong odor, but as they age, bacteria makes them develop an ominous stench.
The Microbial Process in Eggs
At the core of the rotten egg sulfur smell is an intricate microbial process involving the metabolism of sulfur compounds. This process unfolds in several stages, influenced by different bacteria and their environments.
Bacterial Contamination: After an egg is laid, it can get contaminated with bacteria, including salmonella or other spoilage organisms.
Decomposition: As the egg ages, bacteria penetrate the porous shell and metabolize the proteins inside.
Production of Hydrogen Sulfide: Like in other scenarios, some of these bacteria will produce hydrogen sulfide as they feed on sulfur-containing proteins in the egg. Sulfate-reducing bacteria, which thrive in low-oxygen areas, are the primary creators of hydrogen sulfide.
Odor Detection: Resultant hydrogen sulfide accumulates, causing the unmistakable smell of rotten eggs. The egg is no longer safe to consume.
A simple water test: if an egg floats, it’s due to internal gasses and an indicator it may be spoiled. Best to toss it.
Organic Matter Decomposition: As organic matter breaks down, it enriches the environment for these bacteria, resulting in a spike in hydrogen sulfide production.
Gas Release: Hydrogen sulfide is volatile and can escape into the environment, which is why we often encounter this smell in damp areas like swamps or poorly ventilated basements.
Bacterial Interactions: Various bacteria work together in this process. For instance, when proteins decay in rotten food or the gut, they release sulfur-containing amino acids, which are subsequently converted into hydrogen sulfide through bacterial action.
Non-Fiction Books:
Fiction Books:
READ: Lora Ley Adventures - Germanic Mythology Fiction Series
READ: Reiker For Hire - Victorian Detective Murder Mysteries