INEEL And WSU Researchers Coax Bacteria To Clean Up Toxic Chromium

October 08, 1998

Idaho Falls, ID -- A team of researchers has tricked bacteria from contaminated soil into cleaning up the toxic heavy metal chromium. The Department of Energy has awarded the collaborators funds to study the basic science behind this bacterial conversion. Eventually, the researchers hope to optimize the microbial action at contaminated sites simply by adding the appropriate nutrients.

James Petersen, chemical engineering professor and director of the Center for Multiphase Environmental Research at Washington State University, and scientific fellow William Apel, at the Idaho National Engineering and Environmental Laboratory, received a three-year grant of $767,000 from the Natural and Accelerated Bioremediation Research (NABIR) program of the DOE.

Established last year, NABIR recognizes that existing bioremediation technology is insufficient to clean up many of DOE's contaminated sites. The program supports basic research into how biological systems can be used to remediate hazardous and radioactive contaminants in soils and groundwater.

Chromium is a heavy metal naturally found in several different forms. Hexavalent chromium, often in a form called chromate, is toxic even at low concentrations. At high concentrations, it can cause cancer and damage DNA. Chromate found in the environment is generated almost exclusively by human activities-it is left over from mining operations, agricultural procedures, and oil refining. It is a contaminant in almost one third of Superfund sites. Trivalent chromium, on the other hand, is a benign form of the metal that is actually an essential element for good nutrition.

In previous research funded by the INEEL University Research Consortium, Petersen and biochemistry colleagues at WSU, in collaboration with microbiologists led by Apel at INEEL, demonstrated that bacteria normally found in contaminated soils are capable of converting the hexavalent chromium to trivalent chromium by a chemical process called reduction. However, a major block to this process is the microbe's preference for reducing nitrate rather than chromate.

Nitrate is in great supply in the microbe's natural environment. The ultimate goal of this bioremediation approach is to induce resident bacteria to clean up toxic chromium within the contaminated settings. Therefore, the researchers needed to find conditions under which chromate is reduced instead.

Bringing bacteria from several contaminated sites-including DOE's Superfund-listed Hanford site in southeastern Washington state-to the lab, the researchers found feeding conditions under which bacteria would reduce chromate to nearly undetectable levels. "We've converted a carcinogenic, hazardous compound to a non-hazardous one," Petersen said. The researchers suspect that, under certain growth conditions, the bacteria commandeer an enzyme with a different function.

"Petersen has been playing a trick on the bacteria, in a way," said Apel. "The bacterial enzymes are promiscuous." "No enzyme has evolved to use chromium," said Petersen. He thinks the bacteria might be using the same enzyme they use to reduce nitrate to reduce chromium. "We are trying to determine what are the best sugars and nutrients to get chromium reduced, to determine what effect other contaminating species (such as uranium and technetium) have on chromium reduction and what the relative concentrations of chromate and nitrate do to the amount of reduction," said Petersen.

The team will also study the biochemical pathway that the bacteria use to convert hexavalent chromium to trivalent chromium. And they plan to demonstrate the ability of resident microbes to decontaminate heavy metals using bacteria-containing soil obtained from contaminated DOE sites, including the Hanford site. The three-year project started in September of this year.

DOE/Idaho National Laboratory

Related Bacteria Articles from Brightsurf:

Siblings can also differ from one another in bacteria
A research team from the University of Tübingen and the German Center for Infection Research (DZIF) is investigating how pathogens influence the immune response of their host with genetic variation.

How bacteria fertilize soya
Soya and clover have their very own fertiliser factories in their roots, where bacteria manufacture ammonium, which is crucial for plant growth.

Bacteria might help other bacteria to tolerate antibiotics better
A new paper by the Dynamical Systems Biology lab at UPF shows that the response by bacteria to antibiotics may depend on other species of bacteria they live with, in such a way that some bacteria may make others more tolerant to antibiotics.

Two-faced bacteria
The gut microbiome, which is a collection of numerous beneficial bacteria species, is key to our overall well-being and good health.

Microcensus in bacteria
Bacillus subtilis can determine proportions of different groups within a mixed population.

Right beneath the skin we all have the same bacteria
In the dermis skin layer, the same bacteria are found across age and gender.

Bacteria must be 'stressed out' to divide
Bacterial cell division is controlled by both enzymatic activity and mechanical forces, which work together to control its timing and location, a new study from EPFL finds.

How bees live with bacteria
More than 90 percent of all bee species are not organized in colonies, but fight their way through life alone.

The bacteria building your baby
Australian researchers have laid to rest a longstanding controversy: is the womb sterile?

Hopping bacteria
Scientists have long known that key models of bacterial movement in real-world conditions are flawed.

Read More: Bacteria News and Bacteria Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.