I am particularly intrigued by processes occurring at the aqueous/solid interface, both in terms of understanding the fundamental chemistry occurring in such systems and applying concepts to remedial or preventative technologies. This principle unified my otherwise disparate graduate and postdoctoral studies. My graduate research focused on TiO2-photocatalyzed oxidation of As(III) to As(V) and its potential for application in water treatment.    During my postdoctoral fellowship, I moved from mineral surfaces to biological surfaces as I examined the chemical and biophysical interactions between the predatory bacterium Bdellovibrio bacteriovorus and the cells it preyed on.  Most of my current research addresses surface chemistry questions as applied to bacteria of environmental relevance.

Current projects:

Bioremediation of polycyclic aromatic hydrocarbons by Pseudomonas putida

P. putida cells clustered between two anthracene crystals.

Pseudomonas putida is a Gram-negative bacterium that aerobically degrades a variety of soil and groundwater contaminants, including polycyclic aromatic hydrocarbons (PAHs) such as anthracene, phenanthrene, acenapthylene, fluoranthene, and pyrene. For this reason, it is important in bioremediation.  Addition of aqueous phase biosurfactants has been shown to increase rates of PAH bioremediation under several conditions.  Conversely, the presence of PAHs can stimulate aqueous phase biosurfactant production in Pseudomonads.  This latter phenomenon is of particular interest because PAHs may induce production of new or greater quantities of biosurfactants, which could then be harvested for industrial purposes. .  At the same time, exploration of this relationship from a chemical perspective will help to better understand the processes affecting bioremediation rates.  My students and I are examining the surface properties of  P. putida grown in the presence and absence of PAHs using a variety of techniques including atomic force microscopy and mass spectrometry.


Biochemical causes and implications of the predatory versus nonpredatory lifestyles of Bdellovibrio bacteriovorus

B. bacteriovorus is a predatory bacterium that attacks a wide variety of Gram-negative bacteria but is harmless to eukaryotes. This characteristic has led to speculation about whether it can be used in agriculture, industry, and even medicine as an alternative to antibiotics. However, B. bacteriovorus can also subsist in a host-independent (HI) form in which it uses nutrients from the external media like most other bacteria.  Understanding what governs the switch between predatory and HI B. bacteriovorus is crucial to assessing whether and how B. bacteriovorus might be utilized to combat harmful bacterial species.

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