Laboratory for Aquatic Environmental Microbiology and Chemistry

Research in our laboratory within the Zilber School of Public Health, Environmental and Occupational Health is concerned with characterizing factors that regulate human exposure to naturally occurring or anthropogenic toxins in water or wastewater. We are particularly interested in understanding how microbial communities affect the concentration, fate and toxicity of harmful chemicals in the aquatic environment. The ultimate goal of this research is to formulate models (either numerical or conceptual) of toxin production, release, and degradation in aquatic ecosystems. Since the diversity of biochemical functions performed by microorganisms is only beginning to be realized, this research is both challenging and intriguing. Currently our research is focused on two project areas.

The environmental fate and toxicity of chemical pollutants is complicated by the large number of potential biological transformations that a chemical may undergo once released into the environment. In some cases the breakdown products may be more harmful than the parent compounds. This appears to be the case for phenyl urea pesticides such as Linuron, Diuron, Triclocarban and related compounds, which are slowly transformed by bacteria to carcinogenic chloroanilines in the environment. All of these compounds, as well as their chloroaniline degradation products have estimated half- lives exceeding 100 days in freshwater and have the potential to bioaccumulate in freshwater organisms. We are investigating how microbial processes control the distribution of these compounds and their toxic end- products in freshwater and freshwater resources including “seafood,” drinking water and groundwater. These transformations are studied in laboratory scale microcosms, in fish bioassays, and in the natural environment through field surveys.

Freshwater harmful algal blooms.Recurrent nuisance and/or toxic algal blooms are a consistent problem in eutrophic lakes, rivers and coastal oceans. In recreational eutrophic lakes hepatotoxins and neurotoxins produced by cyanobacteria are an ongoing threat to public health. Beaches in many regions are monitored and closed by local health authorities when problems are suspected. However, despite these closings acute illnesses of swimmers are still reported. This illustrates the need for better monitoring methods and greater understanding of factors controlling human exposure to toxins. Our research is directed at understanding cyanobacterial toxin dynamics in lakes relative to the molecular ecology of cyanobacteria. We are also developing new autonomous monitoring systems for cyanobacteria and their toxins based on sensor-equipped buoy platforms. Finally, we are developing models of cyanobacterial growth and toxin production, which we hope will aid in reducing human exposure to algal toxins.

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