Researchers to study the role of bacteria in sediments

Brent Peyton and Rajesh Sani, researchers in the Washington State University Center for Multiphase Environmental Research, received a four-year $1.2 million grant for a project to characterize indigenous microorganisms in the metal-contaminated sediments of Idaho’s Lake Coeur d’Alene and to analyze their role in the transport of metals through the environment.

The work, sponsored by the National Science Foundation’s Biocomplexity Program, could someday be used to better predict metal transport processes in contaminated sediments and improve bioremediation strategies.

A long history of mining in the Pacific Northwest has led to high levels of heavy metals in the sediments of some area lakes and rivers. However, microorganisms that live in these metal-contaminated sediments, such as those in Lake Coeur d’Alene, are capable of detoxifying their environment and thus constitute an important factor in the biogeochemical cycles of these metals. The researchers hope to understand and quantify the biogeochemical reactions controlling the fate and transport of these metals to effectively model and predict changes in metal concentrations and microbial populations.

The project focuses on characterizing of microbial communities and developing a quantitative model to describe microbially-driven reactions of the toxic metals, lead, copper and zinc. Peyton and Sani will use DNA (deoxyribose nucleic acid) extraction to characterize the microbial diversity of sediments collected from the metal-contaminated Lake Coeur d’Alene. In the laboratory, they will then measure changes in the microbial populations, with time and location, as they are exposed to higher metal stress.

Although there are typically millions of microorganisms and hundreds to thousands of different bacterial species in most any teaspoon of soil, the researchers will focus on a few dominant representatives. Peyton and Sani theorize that unique, metal-tolerant microorganisms may be dominant in the sediments and that these microorganisms may influence the movement of the contaminants through the environment.

In collaboration with Timothy Ginn, faculty member at the University of California-Davis, and scientist Nicholas Spycher of Lawrence Berkeley Labs, the researchers will also develop computer simulations to help explain the interaction of the bacteria with the metals in the Coeur d’Alene River Basin and to understand the conditions that would make for optimal clean-up.

“In the natural environment, the biogeochemistry becomes very complex,” Peyton said. “We hope to better understand how the types of toxic metals, the variety of soil minerals and different types of microorganisms interact. They each play a role.”