Copper Kills Harmful Bacteria, UA Researchers Find

Libin Zhu, Sadhana Ravishankar's lab manager, tested the survivability of Salmonella on copper alloys with varying copper concentrations. The bacteria cells sometimes died out on copper surfaces within hours, while they survived for up to two weeks on stainless steel. (Photo by Beatriz Verdugo/UANews)
Libin Zhu, Sadhana Ravishankar's lab manager, tested the survivability of Salmonella on copper alloys with varying copper concentrations. The bacteria cells sometimes died out on copper surfaces within hours, while they survived for up to two weeks on stainless steel. (Photo by Beatriz Verdugo/UANews)

Each year a tiny, rod-shaped species of bacteria with a fondness for proliferating on human food causes numerous cases of food poisoning around the world, sometimes leading to severe illness and even death.

The culprit, Salmonella enterica, is a leading cause of diarrheal illness worldwide, said Sadhana Ravishankar, an assistant professor in the University of Arizona department of veterinary science and microbiology.

But Ravishankar’s lab may have discovered a way to reduce the number of food poisoning cases due to Salmonella and possibly other bacteria: prepare food on surfaces made with materials that contain some amount of the element copper, known as copper alloys.

Ravishankar’s lab collaborated with Chris Rensing, formerly an associate professor in the UA department of soil, water and environmental science and now at Research Triangle Institute International, for the study, which was published recently in the journal Food Microbiology.

“Chris Rensing had already done some research with copper, and he knew that copper surfaces have antimicrobial activity,” said Ravishankar.

The International Copper Association donated six samples of copper alloys for the study, including samples of copper mixed with metals such as nickel, iron, chromium, phosphorous and tin that varied in their copper concentration from 60 to 99.9 percent.

Copper is harmful to bacteria because it reacts with oxygen in the atmosphere over time in a process called oxidation, which produces a residue that is toxic to some bacteria. Oxidation is what makes pure copper change in color over time from a rusty gold to a watery green.

“We decided to see the antimicrobial effect of all these copper alloy surfaces on Salmonella,” said Ravishankar. Salmonella was selected as the microbial guinea pig for the study because of its prevalence and the significant harm it causes worldwide because of diarrheal disease.

Read more from the July 13 issue of the Arizona Daily Star at the link below.

Date released: 
Jul 17 2012
Contact: 
Sadhana Ravishankar