Frank Löffler, Kirsti Ritalahti and Kostas Konstantinidis (Biology and Civil & Environmental Engineering) have received a $460,000 grant from the National Science Foundation for an interdisciplinary project that advances scientific understanding and fosters environmental engineering applications. Soil, sediment and subsurface environments harbor a tremendous diversity of microbes, and understanding how such complex systems evolve, function, and respond to environmental changes has been a major research goal. While previous reductionist approaches that focused on individual bacterial populations have provided a wealth of valuable information, if we wish to truly understand how complex microbial communities function, the interactions and interdependencies between different populations inhabiting the same environment must be explored.
The premise of this project is that many bacteria engage in unknown interactions with neighboring organisms, and that these interspecies links can be characterized using microbiological and genome-enabled approaches. Dehalococcoides and free-living, pleomorphic spirochetes (FLiPS) are members of natural river sediment and aquifer microbial communities. Dehalococcoides are highly specialized bacteria that gain energy for growth by removing halogen substituents from many hydrocarbons, including priority pollutants. This process is called organohalide respiration, and as the bacteria breathe halogenated hydrocarbons (just like we breathe air), the contaminants are detoxified. Dehalococcoides bacteria grow very poorly in isolation but perform robustly in mixed cultures when FLiPS are present. Conversely, FLiPS benefit from Dehalococcoides, and a major goal of the project is to explore the biomolecular basis of these microbe-microbe interactions. This project will characterize unexplored microbe-microbe interactions (symbiosis) at the fundamental, molecular level and shed light on the evolutionary mechanisms that lead to beneficial interactions between distinctly different microbial populations.
This research project will generate new understanding on how microbe-microbe interactions develop, operate, and persist, while affecting specific functions of the community (e.g., detoxification of halogenated hydrocarbons). This project will not only advance knowledge of Dehalococcoides and spirochete biology, but will further improve our predictive ability how microbial communities function and respond to perturbations. The spirochetes that support Dehalococcoides activity share unusual properties compared to traditional spirochetes, some of which can cause disease (e.g., Lyme disease, Leptospirosis, Syphilis). Hence, this research effort also has implications for the medical field by determining the genetic determinants that distinguish pathogenic from benign spirochetes.