Grantee Research Project Results
1998 Progress Report: Development and Application of Spectroscopic Probes for Measurement of Microbial Activity in Aquatic Ecosystems
EPA Grant Number: R825159Title: Development and Application of Spectroscopic Probes for Measurement of Microbial Activity in Aquatic Ecosystems
Investigators: Arnosti, Carol , Blough, Neil V.
Institution: University of North Carolina at Chapel Hill , University of Maryland - College Park
EPA Project Officer: Packard, Benjamin H
Project Period: November 1, 1996 through October 31, 1999 (Extended to April 30, 2001)
Project Period Covered by this Report: November 1, 1997 through October 31, 1998
Project Amount: $405,811
RFA: Water and Watersheds Research (1996) RFA Text | Recipients Lists
Research Category: Watersheds , Water
Objective:
Measuring the net degradative capabilities of a complex community of microorganisms is a major challenge in understanding carbon cycling, because we lack the means to measure the rates at which bacteria hydrolyze large macromolecules to smaller pieces that can in turn be further transformed or remineralized. We are developing a new generation of sensitive spectroscopic probes to measure extracellular enzymatic hydrolysis rates of organic macromolecules in the water column and sediments. This approach is based on intramolecular energy transfer between donor and acceptor groups covalently attached to single macromolecules, so hydrolysis rates can be measured using simple fluorescence techniques. We are initially using polysaccharides as our target macromolecules, since they comprise a significant proportion of total organic matter, and recent studies (Amon and Benner, 1994) have highlighted their importance in the global carbon cycle.Much of our current knowledge about microbial behavior and dynamics is based on laboratory studies of pure or mixed cultures of bacteria. Although these studies have yielded significant insights into microbial biochemistry and physiology, they reduce the complexity of natural aquatic systems to the point where their relevance to broader issues of biogeochemical cycling is questionable. The fluorescent-labeled probes will provide the means of making rapid, high-resolution measurements of specific enzymatic activities with minimal disturbance to the naturally complex microbial community, providing a more realistic picture of the transformations which actually take place. The new analytical approaches we are developing will lead to better understanding of a major process governing the dynamics of organic matter degradation in aquatic ecosystems.
Progress Summary:
The probes we have synthesized to date enable us to obtain qualitative measurements of extracellular enzymatic hydrolysis in sediment and seawater samples, as well as in laboratory experiments with purified enzymes. They should be extremely useful as a rapid screening tool for high numbers of samples which must be processed rapidly.Future Activities:
We intend to carry out further lab and field measurements with both short-chain and long-chain polysaccharide probes in order to calibrate probe response and extend our range of field applications.Journal Articles:
No journal articles submitted with this report: View all 13 publications for this projectSupplemental Keywords:
RFA, Scientific Discipline, Water, Hydrology, Water & Watershed, Environmental Microbiology, Ecology and Ecosystems, Watersheds, coastal watershed, microbial pollution, aquatic ecosystems, hydrolyzing organic macromolecules, spectroscopic probes, carbon nutrientsProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.