Our laboratory uses a variety of molecular and functional methods to estimate species diversity, examine how microbial communities interact with various environmental components, and explore linkages between community structure and function. We are also actively developing new techniques to detect specific microbial activities in the environment.

We have been involved in research relating to the bioremediation of chlorinated solvents for over a decade, and a major thrust of this research has been to develop and assess enzyme activity-dependent probes specific for enzymes involved in the aerobic cometabolism of solvents, such as trichloroethylene. Recently we completed field investigations using our probes at the Idaho National Engineering and Environmental Laboratory Test Area North site, in conjunction with colleagues at North Wind Inc. The results provide solid evidence in support of natural attenuation in aerobic regions of that TCE plume. We are currently taking steps to move this technology into the practice of site remediation in Arizona and throughout the west.

We have also investigated the microbiological fate of agrochemicals, such as polyacrylamide (PAM), in agricultural soils; currently these studies are now being expanded to address the fate of PAM in aquatic systems receiving agricultural effluent.

We are also involved with researchers from Idaho State University (my former institution) in a collaborative project to examine microbial community composition and dynamics in constructed wetland sediments and along thermal gradients of hot spring systems in Oregon. Finally, we are beginning to explore the role of viruses in structuring prokaryotic communities in extreme environments.

Our laboratory group includes postdoctoral associate, M. Hope Howard (michelle.howard@nau.edu), graduate students Scott Clingenpeel and Brenda Harrop, and eight undergraduate researchers. One of my main goals at NAU is to link ongoing research with hands-on instruction to provide rigorous, meaningful education in environmental microbiology for students at all levels. I welcome inquiries regarding potential research opportunities from graduate and undergraduate students interested in these topics.

This faculty member is also a mentor in the NSF IGERT graduate training program: NAU’s IGERT PhD program seeks to identify key links between genes and the environment and is designed to train exceptional graduate students in molecular genetics, environmental sciences, and spatio-temporal modeling.

My associates and I are part of the Bioremediation Research Initiative. Funded through the State of Arizona Proposition 301 ERDENE Initiative, this research is focused on applying multiple technical approaches to the challenges of environmental pollution. Contaminated vadose zone and groundwater sites are being investigated at several different scales, including molecular (detection of specific genes coding for contaminant-degrading enzymes), community (composition of prokaryotic communities, including members with key degradative capacities), functional (detection of specific enzyme activities using enzyme activity probes), and environment (analysis of contaminant fate using stable isotope technology). The linkages between genetic potential and realized contaminant removal are being explored not only to better understand active bioremediation processes (Schwartz and Scow 1999, Schwartz et al. 2002), but also to verify the potential for passive monitored attenuation. For example, we have developed a series of enzyme activity-dependent chemical probes that give fluorescent signals only when the enzyme of interest is induced, expressed and actively functioning in the environment (Keener et al. 2001). These probes are designed to target enzymes that break down environmental toxins, such as toluene and chlorinated solvents (Clingenpeel et al. 2005). This technology is being employed at a variety of sites to assess phenotypic activity required for contaminant breakdown. Paired molecular analyses provide context for interpreting functional probe data and determining if relevant processes, such as induction, enzyme inhibition etc., are occurring at a site. Combining these data with information relative to spatial heterogeneity of microbial distribution in the subsurface (LaViolette et al. 1999) can ultimately result in workable plans for site remediation (Schwartz and Scow 2001). Another novel application of this work involves specific labeling of bacterial DNA with stable isotopes through incubation with isotopically labeled contaminant compounds. 13C-DNA is isolated via differential centrifugation; subsequence sequence analysis of the heavy fraction reveals the identities of organisms, which incorporated contaminant-carbon into their genome. Using these cutting edge approaches and related methods, IGERT students will develop projects linking detection and quantification of specific genes with relevant processes; modeling of potential remediation outcomes across temporal and spatial scales is an important interdisciplinary component of these studies.