Research

Signaling in Rhizobia (click for more information)
Symbiotic Rhizobia fix atmospheric nitrogen into forms that can be used by their plant hosts. Like all bacteria, Rhizobia respond to carbon and nitrogen levels internally, and in their environment. This allows them to make best use of available resources and to integrate their metabolic pathways when they live as individuals in the soil, or to integrate their metabolism with their host's metabolism when they are living symbiotically.

How soil bacteria sense and avoid being eaten by protist predators (click for more information)
The soil protists Colpoda and Cercomonas can consume huge numbers of soil bacteria in a short period of time. We are trying to understand how the soil bacteria Sinorhizobium meliloti and Pseudomonas fluorescens detect and change their behavior in order to avoid being eaten. In addition we are conducting research to see if these protists can move live bacteria long distances through the soil.

Symbioses in termites (click for more information)
The Northeastern subteranean termite Reticulitermes flavipes, like many termites, has a community of protists and bacteria in its gut that ferment cellulose and allow it to live on a diet of wood. As part of a NSF-funded EFRI grant, we are studying how the gut bacteria communicate via cell-surface proteins with the protist symbiontsion the gut, or with the termite gut epithelium.

Monitoring biology in complex environments (click for more information)
Complex environments such as the soil are heterogenous in terms of nutrients, chemical conditions and physical conditions over spatial scales of less than a micron. There are very few techniques that allow monitoring of conditions on such small scales. We are collaborating in the development of bacterial biosensors that are able to report on the enviroment on scales that are the same size as they are (roughly 1-5 microns). These bacteria are allowing us to monitor how the soil around roots changes when it is altered by changes in plant physiology.