Postdoctoral Research Associate
Soil Ecosystem Science Team
Earth and Biological Sciences Directorate
Pacific Northwest National Laboratory
Postdoctoral Research Associate
Soil Ecosystem Science Team
Earth and Biological Sciences Directorate
Pacific Northwest National Laboratory
Soil microbial ecology and biogeochemistry at coastal terrestrial-aquatic interfaces
Terrestrial-aquatic interfaces (TAIs) are at the forefront of climate change impacts such as sea level rise, extreme weather events and shoreline changes. Inundation of the coastline with saline and freshwater causes wetting events followed by intermittent dry spells which can alter the microbial functions in these TAIs. The impact spreads along a gradient of wetland, transition and upland areas which differ in soil chemistry, indicator microbial taxa and vegetation. Using a suite of lab based intact soil core incubation experiments and field samples from Chesapeake Bay and Lake Erie, my research focuses to tease apart the unique microbial functions that dominate these environments. I will use a mix of amplicon sequencing, metagenome and metatranscriptome analysis, and combine these approaches with soil physics and soil chemistry to better understand the dynamics of this ecosystem.
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For more information on the project please visit, https://compass.pnnl.gov/.
Resuscitation of soil microbes to plant stress signals and impacts of abiotic stress on rhizosphere microbiome assembly
Roughly eighty percent of the soil microbial community is dormant at a given stage, and can resuscitate to be a part of the active community with implications for microbiome structure and function. The role of resuscitated microbes are particularly important after an environmental perturbation or stress when conditions fluctuate and community members shift in competitiveness. We hypothesize that stressed plants can selectively resuscitate soil microbes and recruit them to the rhizosphere to promote resilience. I have investigated the effect of plant stress signals such as phytohormones on microbial dormancy-resuscitation dynamics. I have used high throughput growth assays as well as amplicon sequencing techniques to answer these questions. My research also explored how stress conditions such as drought and pathogen exposure impacts the rhizosphere community in terms of active membership.
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Check out this research here: 10.1101/2023.06.06.543716
Investigating the effects of biodegradable plastic film mulching on soil microbiome
Plastic film mulching is a common agricultural practice that has been used for years to improve crop yields. Conventional polyethylene (PE) plastic mulch films (or black plastic) are used widely for this purpose. However, polyethylene is not biodegradable and poses severe environmental concerns when it comes to its post-harvest disposal. Biodegradable plastic films (BDM) hold promise as a sustainable alternative to polyethylene. BDMs can be tilled into the soil where resident soil microbes are expected to degrade them. Using high throughput amplicon sequencing and biogeochemical techniques, my work shows that biodegradable mulches have comparable influences on soil microbial communities compared to polyethylene mulch films at least over the short term. This study was replicated in two diverse climates of Knoxville, Tennessee, and Mount Vernon, Washington.
Check out this work here: 10.7717/peerj.9015
Relevant review paper: 10.3389/fmicb.2018.00819
Plastic associated microbiomes
Plastic mulches used in the field are exposed to soil microbes for a complete growing season. We hypothesized that after exposure to the field there will be a preferential enrichment of selected soil microbial taxa on BDMs compared to polyethylene (PE) mulch. Combining high throughput amplicon sequencing with qPCR, confocal microscopy, enzyme assays and physicochemical testing of mulch, I demonstrated mulch degradation in laboratory based enrichment cultures and characterized the plastic-associated microbiome in both lab enrichments and on agriculturally weathered mulch. My findings reveal a distinct community on BDMs compared to PE with the composition differing depending on the mulch formulation used.
Check out this work here: 10.3389/fmicb.2020.587074
Long term effects of natural and anthropogenic stressors in agroecosystems and implications on soil health
Apart from the short term impacts, I am also interested in long term effects of natural and anthropogenic stressors in terrestrial environments. Using soil burial studies we are trying to understand how plastic fragments persist in soil over time and what their end fate is. How long are BDMs persisting in soil and what are the implications on soil health over time? These are questions that are still under investigation. I am also interested in understanding how long term exposure of plants to xenobiotics and climate change events will impact the soil and rhizosphere microbiome, and plant productivity.
Check out the manuscripts relevant to this research: 10.1016/j.agee.2018.12.002
Controlled studies- role of abiotic factors on organic matter decomposition
Lab based studies where we can optimally control parameters of interest are critical to predicting field performance. I am interested to explore how abiotic treatments such as elevated temperature and nitrogen amendments control organic carbon degradation in agroecosystems. Extending this idea to plant-microbe interactions, I have investigated soil microbial resuscitation dynamics in response to phytohormones released during abiotic stresses such as drought.
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Check out this research:10.5194/egusphere-2022-1333, now accepted and in production.
