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Woods Hole Oceanographic Institution

Elizabeth B. Kujawinski

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Publications
»Using stable isotope probing to characterize differences between free-living and sediment-associated microorganisms in the subsurface.
»DOM in Lake Superior
»Deepwater Horizon hydrocarbons in the marine environment
»Microbes and marine DOM, Ann. Rev. Mar. Sci. 2011
»Greenland ice sheet outlet glacier: Insights from a new isotope-mixing model
»Groundwater DOM, GCA 2011
»Dispersants & DWH, ES&T 2011
»FT-MS variability in DOM, Org Geochem 2010
»Predatory Flavobacteria, FEMS Microb Ecol 2010
»Greenland Ice Sheet DOM, GCA 2010
»Protozoa and bacteria in aquifers, FEMS Microb Ecol, 2009
»Source markers in DOM, GCA 2009
»Automated data analysis, Anal. Chem. 2006
»Marine DOM and ESI FT-ICR MS; Marine Chem 2004
»DOM extraction by C18; Org. Geochem. 2003
»Black carbon by ESI FT-ICR MS; ES&T 2004
»ESI FT-ICR MS review; Env. Forensics 2002
»Marine protozoan surfactants; Marine Chem. 2002
»ESI MS and NOM; Org. Geochem. 2002
»ESI FT-ICR MS & humic acids; Anal. Chem. 2002
»Protozoan DOM & PCBs; ES&T 2001
»Protozoa & Fe, Th, C; Aquat. Microb. Ecol. 2001
»PCB uptake by protozoa; AEM 2000


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E. B. Kujawinski, J. W. Farrington, and J. W. Moffett., Evidence for grazing-mediated production of surface-active material by marine protists., Marine Chemistry 77: 133-142, 2002

Surface-active organic compounds, or surfactants, play important roles in a variety of upper ocean processes, including surface microlayer physics and gas exchange, and the aggregation of colloidal material. Although surfactants are presumed to be produced primarily by phytoplankton, production by protozoan grazers has not been investigated.  In general, the processes controlling surfactant abundance in the field are poorly understood.  In this study, a two-phase laboratory system containing protists and prey was used to examine the possibility of surfactant production during protozoan grazing.  Three protist species were examined, a scuticociliate, Uronema sp. (10-15 mm), and two flagellates, Cafeteria sp. (2-4 mm), and Paraphysomonas imperforata (4-8 mm).  For all experimental cultures, protozoan inocula were added to rinsed bacterial suspensions (Halomonas halodurans) in sterile seawater.  Surfactants, dissolved organic carbon (DOC) and population dynamics were monitored until protists had reached stationary growth.  Surfactant activities increased during protozoan exponential growth.  Surfactant production in the ciliate cultures was significantly higher than in either of the flagellate cultures.  Bacterial controls maintained low DOC concentrations and surfactant activities.  Estimates of protozoan surfactant production rates range from 10-8 to 10-9 mg prot-1 h-1 (Triton X-100 equivalents).  Under non-bloom conditions (103 protozoan cells mL-1), we estimated a surfactant production rate of 10-5 to 10-6 mg h-1 (within 1 mL of seawater), which is comparable to estimates of phytoplankton production of surface-active material during blooms.  Thus, protozoan grazers constitute a potentially significant source of surface-active material in areas where protists are abundant, such as the sediment-water interface and microbial loop-dominated oligotrophic regimes.

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