INFLUENCE OF MULTI-FACTOR GLOBAL CHANGE ON SOIL MICROBIAL COMMUNITY STRUCTURE AND FUNCTION

Fire regimes have been altered greatly by human activity, and are likely to be altered further in the coming century by climate change in the western United States. Specifically, fires in California are likely to burn more rapidly and with higher intensity in the coming century under warmer climate scenarios. In addition, multiple interacting effects of regional and global climate change may also increase fire incidence. For instance, increases in nitrogen deposition and fertilization, altered precipitation and drought patterns, and higher surface temperatures may substantially increase aboveground plant biomass, thus increasing fuel for fires. The Jasper Ridge Global Change Experiment (JRGCE), located in an annual grassland near Palo Alto, CA, is a long-term experiment that has manipulated four key factors of global and regional climate change for over a decade. The four global change factors manipulated in this experiment are CO2 concentration, temperature, precipitation levels and nitrogen addition. In 2011, a prescribed burn was performed at this site to examine the interacting effects of multi-factor global change with fire.

This project in the Docherty lab: works with collaborators through the JRGCE to examine the effects of these treatments and fire through time on several types of microbial communities that perform nitrogen cycling and on general microbial biodiversity. In particular we focus on the long-term effect of nitrogen addition/deposition on ammonia oxidizing Bacterial and Archaeal communities, and the effect of fire on overall interactions of the microbial community with changing biotic and abiotic factors in the surrounding ecosystem.

 

EXAMINING SEASONALITY OF WASTEWATER TREATMENT PLANT FUNCTION IN BIODEGRADING NOVEL GREEN CHEMICALS

Natural and man-made ecosystems alike are constantly exposed to anthropogenic stressors, particularly in the form of chemical pollutants.  While an understanding of the general properties of a chemical is required before widespread use, information concerning the full extent of the environmental impacts of a chemical often emerges only after the pollutant has already severely impacted the environment.   Some notorious examples include the impacts of the insecticide dichlorodiphenyltrichloroethane (DDT) on predatory bird populations, refrigerant chlorofluorocarbons (CFCs) on atmospheric ozone, and the gasoline additive methyl tertiary butyl ether (MTBE) on groundwater.  All three of these chemicals, which have either been banned or tightly regulated due to their detrimental environmental impacts, are prime examples of the costs of environmental effects and clean-up far outweighing the intended benefits. For future chemical design, particularly regarding chemicals with the potential for mass production and use in industry, more environmentally-friendly design needs to be coupled with a more proactive assessment of the environmental risks new chemicals may pose.

This project in the Docherty lab: focuses on the biodegradation of a particular group of novel green chemicals called Ionic Liquids (ILs). These chemicals have been designed for a wide range of uses, and have the potential to replace much more harmful industrial counterparts. However, before widespread use and release into the environment, it is crucial to understand how to clean up these chemicals, either onsite in bioreactors or within a wastewater treatment plant. We are examining the ability of wastewater treatment plants to biodegrade imidazolium and pyridinium-based ILs in different seasons and are isolating and identifying microbial consortia capable of fully biodegrading these chemicals into harmless CO2 and biomass.

ENVIRONMENTAL TOXICITY OF NANOMATERIALS

Engineered nanomaterials (ENMs) are the foundation of the nanotechnology movement. ENMs are currently used in a wide variety of everyday items, ranging from hygiene products to automotic parts, to electronic components to biomedical drug targeting. One of the main benefits of ENMs is their toxicity to microorganisms. ENMs are often used in items such as medical masks, bandages and atheltic wear to prevent microbial contamination. However, when these items are thrown away ENMs will inevitably make their way into the environment, and potentially alter microbiota that are crucial to water and soil biogeochemical cycling.

This project in the Docherty lab: involves collaboration with chemists at WMU to examine the effect of palladium-based ENMs to various types of microorganisms. We are currently examining the effects on pure cultures of microorganisms under laboratory conditions over time and with differently sized aggregates of palladium ENMs. These studies will provide a baseline of data for future studies, where we will focus on multi-trophic level interactions in environmentally realistic conditions.