EAGER: Field-Deployed Microfluidic Trap Array for Discovery and Observation of Microbial Eukaryotes

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Bacteria and protozoa are critical components of aquatic and terrestrial ecosystems, driving biogeochemical processes including carbon fixation, oxygen production, nutrient cycling, and break-down of anthropogenic contaminants. In many habitats, the bacterial community structure and net production are controlled in a top-down fashion by protozoan predation; in turn, predation of protozoa by larger animals mobilizes nutrients and contaminants to higher trophic levels. Despite their importance, relatively little is known about the diversity, biogeography, and ecosystem function of microbial eukaryotes including protozoa, due to limitations of both traditional culturing methods and genetic techniques. New instrumentation is needed to sample, study and understand a broader range of protozoa in natural systems.The objective of this research is to develop a microfluidic field sampling and analysis tool to study the biogeography and function of microbial eukaryotes in natural habitats. Microfluidic samplers will be fabricated with micron-scale physical features in polydimethylsiloxane (PDMS) and glass. Samplers will be selectively baited and placed in different natural environments in order to select for microorganisms based on morphology, behavior, habitat, and prey source, and will enable direct observation of entrapped live protozoa via light microscopy. Genetic analysis of collected eukaryotes and prokaryotes will help provide a unified framework for taxonomic, functional, and genomic information. Together with co-located micro-scale measurements of environmental variables such as pH, temperature, and nutrient concentrations, this work will enable researchers to place microbial eukaryotes within the context of their immediate physical and chemical microhabitats.This work will enable development and validation of a completely new microbial community analysis tool that will be of immediate and practical use to microbial ecologists, aqueous geochemists, engineers, and marine scientists. It may help to answer fundamental questions in biology including what is the relevant physical scale of community structure variations, and to what extent are protozoan species cosmopolitan vs. endemic in natural habitats? Also, a better understanding of microbial community structure and function will permit better predictions of biogeochemical feedbacks as a function of climate change; improved understand the impacts of microbial community structure and function on contaminant uptake and mobilization, and enhanced risk models for environmental reservoirs of microbial pathogens. Future work will integrate a comprehensive suite of sensing capabilities and will deploy devices in a broader range of natural and engineered microbial habitats. The results of this project will be disseminated through peer-reviewed journals and conference presentations that target the biological user community. Implementation of the technology will be enabled by web-posted demonstration videos that illustrate how samplers are designed, created, tested, deployed, and studied back in the lab. All materials will be available online at http://www.cmbe.engr.uconn.edu/facultyshor.html.