top of page
Sylvia Rose

Cupriavidus metallidurans: Metal Eating Gold Making Bacterium

Cupriavidus metallidurans has an extraordinary ability to prosper in toxic environments. Not only does it survive, it turns toxic metals into 24-karat gold. This tiny transformer eats harmful substances such as heavy metals like copper, nickel and chromium for breakfast.



Much enlarged gold nugget from Australian gold mine showing bacterial forms
Much enlarged gold nugget from Australian mine showing bacterial forms (credit: CSIRO)

What is Cupriavidus metallidurans?


In alchemy exist mystic references to a Philosophers' Stone (lapis philosophorum), rumors of the Philosophers' Egg and demonstrations of Philosophers' Wool (zinc oxide ZnO). Now, in toxic waste dumps throughout the world, the bacterium philosophorum really produces gold.


C. metallidurans is a gram-negative bacterium known for exceptional tolerance to a variety of heavy metals, including gold, arsenic, copper, chromium, nickel and cadmium. It's part of the Ralstonia genus of the Burkholderiaceae family.


First isolated from a contaminated site in Belgium in the late 1990s, this remarkable rod-shaped microbe is under extensive scrutiny due to its unique metabolic pathways. This mysterious system allows it to process toxic heavy metals and release tiny nuggets of gold.



Cupriavidus Metallidurans
Rod-shaped Cupriavidus Metallidurans

Cupriavidus metallidurans is capable of thriving in copper concentrations five times higher than those tolerated by most bacteria. This ability makes it a crucial organism in bioremediation projects focused on restoring contaminated environments.


C. metallidurans is predominantly found in industrial settings, such as mining operations, battery manufacturing plants and locations contaminated with heavy metals. The bacterium can be isolated from soil, sediments, and even wastewater in these areas.


Its adaptability allows it to colonize environments lethal to most life forms, where it contributes to bioremediation of toxic waste. It's found in contaminated industrial sites, mining areas and waste disposal plants. Inhabiting soil and water, these bacteria turn toxicity into opportunity.




Like other bacteria, C. metallidurans acquires nutrients through the process of chemotrophy. It gets energy by oxidizing inorganic compounds. Its metabolism is particularly adept at breaking down organic matter and using metals, incorporating them into its cellular processes.


C. metallidurans reproduces asexually through binary fission, where one cell divides to form two identical daughter cells. This process can happen rapidly, allowing the bacterium to multiply swiftly in favorable conditions.


In terms of respiration, the bacterium can switch between aerobic and anaerobic metabolism, making it versatile in various environments. In oxygen-rich conditions, it utilizes aerobic respiration, while in low-oxygen environments, it can revert to anaerobic pathways.



alternate pathways

Most organisms need organic materials for energy. Cupriavidus metallidurans can metabolize inorganic substances like copper and nickel. It uses metals to generate energy, especially significant in environments where organic nutrients are scarce.


Cupriavidus metallidurans mainly respires aerobically, which generates energy in the presence of oxygen. The bacterium reproduces through binary fission, a straightforward process where it divides into two identical cells.


This rapid reproduction enables C. metallidurans to grow quickly in environments abundant in heavy metals, where competition for other nutrients is limited. Beyond ability to metabolize heavy metals, C. metallidurans has specialized mechanisms to detoxify its surroundings.



toxic waste storage
hazardous waste storage

It can sequester toxic metals within its cells, transforming them into harmless forms, effectively cleaning up the environment. The bacterium's ability to handle copper and gold in the soil is crucial.


While both metals can be harmful in high concentrations, the bacterium has adapted to rely on copper for its survival. In the presence of excessive copper, the bacterium can trigger a specific enzyme, named CupA, to expel the surplus copper and maintain its health.


What is the gold-making process of this bacterium?


Perhaps one of the most fascinating aspects of C. metallidurans is its ability to produce gold nanoparticles. Researchers are studying the mechanisms behind this gold-making process. C. metallidurans uses specialized enzymes and proteins to bind and reduce heavy metals.



The gold is produced by C. metallidurans in small nodules or nuggets
The gold is produced by C. metallidurans in small nodules or nuggets

The Process


When exposed to gold ions, Cupriavidus metallidurans reduces these ions to elemental pure gold. It uses specialized enzymatic pathways to facilitate the reduction and form gold nanoparticles.


The bacterium, through its unique metabolic processes, produces visible, metallic particles of gold. The ejected gold appears as tiny, shiny particles scattered in the environment. It's visible, even through the bacterium itself is too small to be seen with the eye.


The bacterium can produce gold nanoparticles with sizes ranging from 5 to 50 nanometers. The process takes a few days. This ability has sparked scientific interest and opened avenues in nanotechnology and sustainable mining practices.



toxic waste on the beach

Can it live outside toxic areas?


Although C. metallidurans thrives in toxic environments, it's not exclusively tied to them. It can survive in less toxic conditions, but its growth and metabolic activity tend to slow down due to presence of other, aggressive organisms.


In non-toxic settings, it may face competition from dominant microbial species. However, when reintegrated into environments with toxic levels of heavy metals, C. metallidurans quickly reestablishes itself with remarkable adaptability.


While it can adapt to various environments, Cupriavidus metallidurans shines in ecosystems burdened by heavy metal pollution. Its remarkable survival strategies demonstrate that life can endure and even thrive in some of the most challenging conditions on Earth.



hazardous vs healthy

Other Gold-Making Bacteria spp.


Recent studies led by CSIRO researcher, Dr. Frank Reith reveal the significance of bacteria in the formation of gold nuggets in Australia. Dr. Reith's study shows specific bacteria found on the gold grains are responsible for precipitating gold from solution.


Through the application of molecular biology techniques, Dr. Reith detects a living biofilm on the surface of the collected gold grains. DNA profiling of this biofilm reveals 30 bacterial species with populations distinct to the gold grains in comparison to the surrounding soils.


Notably, one particular species was consistently found on all DNA-positive gold grains from both locations, identified as Ralstonia metallidurans (obs.) aka Cupriavidus metallidurans through DNA sequence analysis.



making gold
making gold

Facts about Cupriavidus metallidurans


  1. Tolerance: C. metallidurans is resistant to a wide range of heavy metals, including lead, cadmium, and gold.

  2. Bioremediation Potential: Its natural ability to detoxify hazardous substances makes it a potential biological agent for cleaning up contaminated environments.

  3. Nanoparticles: The bacterium's ability to produce gold nanoparticles is being studied for applications in nanotechnology and medicine.

  4. Genomic Insights: Researchers have sequenced its genome, revealing genes responsible for metal resistance and metabolic adaptability.

  5. Versatility: C. metallidurans can metabolize many substrates, including organic compounds, making it versatile in nutrient acquisition.

  6. Global Presence: Cupriavidus metallidurans is found worldwide, particularly in areas affected by mining, industrial waste, and metal processing.

  7. Biotechnology Applications: The process of producing gold from toxic compounds has opened new pathways in nanotechnology, presenting innovative ways to recover precious metals from waste.

  8. Sustainable Mining Potential: Ongoing research explores the use of Cupriavidus metallidurans in bioleaching processes, which help extract metals from ores more sustainably.

  9. Role in Ecosystem Restoration: Beyond its industrial value, Cupriavidus metallidurans contributes to ecological restoration by converting harmful pollutants into safer substances.



waste water toxic
waste water

Non-Fiction Books:


Fiction Books:

READ: Lora Ley Adventures - Germanic Mythology Fiction Series

READ: Reiker For Hire - Victorian Detective Murder Mysteries





19 views

Recent Posts

See All
bottom of page