Our lab examines diverse microbial processes controlling the fate of contaminants under different redox conditions. For example, we examine non-traditional, novel approaches such as biologically mediated abiotic degradation (BMAD) processes. One major research thrust has focused on BMAD processes acting on contaminants of emerging concern such as endocrine disruptors (Im et al., 2015b; Im et al., 2016) and perfluorinated compounds (Im et al., 2014; Im et al., 2015a). Further research will be devoted to demonstrate the relevance of the BMAD processes in natural settings, and to develop in situ remedial alternatives for contaminated groundwater. Research in this area has involved the experimental elucidation of the physical, chemical and biological determinants of these processes by uniquely combining state-of-the-art analytical techniques from the fields of environmental analytical chemistry and environmental microbiology. Novel data mining tools are being developed to parse large in situ dataset acquisitions and discover predictive chemical and biological descriptors of these processes (Lee et al., 2016).
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Plant-microbe interactions describe a broad range of scientific studies concerning how microbes interact with plants at the ecosystem, whole plant, cellular and molecular levels. Plants and microbes can have a variety of interactions including pathogenic, symbiotic and associative – all of which impact plant productivity as well as the environment and society in the long term. Our lab examines plant-microbe interactions using plant cell culture for environmental engineering applications. For example, certain plant species have been reported to produce biological nitrification inhibitors (BNIs) to compete with microbial bacteria/archaea over nitrogen sources. We are trying to integrate such an interaction in a novel strategy to mitigate greenhouse gas (N2O and CH4) emissions from anthropogenic sources such as agriculture and landfills.
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Reductive dehalogenation is one of the primary attenuation mechanisms of halogenation organic compounds by substituting halogen ion with hydrogen ion. Biological reductive dehalogenation is often catalyzed by certain species of bacteria. Sometimes the bacterial species are highly specialized for certain halogenated contaminants; for example, Dehalococcoides is the only known bacteria to transform tetrachloroethene (PCE; one of the most frequently detected groundwater contaminants in US) to "environmentally benign" ethene. This group of bacteria use chlorinated ethenes as respiratory electron acceptors for energy generation. Just like we breathe oxygen, these naturally occurring bacteria breathe chlorinated ethenes. Our lab examines (1) the inhibitory effect of fluorinated compounds on Dehalococcoides, and (2) survival strategy of Dehalococcoides under salinity stress.
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Microorganisms have significant impacts on agricultural productivity and sustainability, yet we know much less about their biodiversity than we do for plants and animals. Conserved forages (e.g., haylage) are an integral part of raising livestock, and at the same time, they serve as ideal habitats for diverse microorganisms (e.g., methanogenesis, methanotropy, denitrification, and non-denitrifying nitrous oxide reduction). Therefore, it is particularly important to understand the function of dominant microbial species in the conserved forages. To provide new insights into the relationship between microbiomes and their function, this project will focus on the production and reduction of greenhouse gases (GHGs; i.e., methane and nitrous oxide) attributable to forage conservation. The ultimate goal is to predict GHG emission potentials from the phylogenetic diversity of conserved forage microbiomes. To achieve this goal, we will (1) identify key environmental drivers of the emissions through coupled field and laboratory investigations, and (2) examine microbial community composition and phylogenetic diversity of conserved forages via high throughput sequencing and metagenomics. These concerted efforts will provide mechanistic understanding of GHGs emissions from these unaccounted yet abundant sources.
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