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Marine Ecology Progress Series

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MEPS 524:55-69 (2015)  -  DOI: https://doi.org/10.3354/meps11209

New tracer to estimate community predation rates of phagotrophic protists

Alexander B. Bochdansky*, Melissa A. Clouse

Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, VA 23529, USA
*Corresponding author:

ABSTRACT: Predation of eukaryotic microbes on prokaryotes is one of the most important trophic interactions on Earth, representing a major mortality term and shaping morphology and composition of prokaryotic communities. Here we introduce and validate a new tracer to determine predation rates on prokaryotes. Minicells of Escherichia coli marked with a bright green fluorescent protein (GFP) vector have many operational advantages over previously used prey analogs such as fluorescently labeled bacteria. GFP-minicells are similar in size to naturally occurring bacteria from a variety of environments including the oligotrophic open ocean and the deep sea. They are relatively stable against microbial and light degradation, are easy to grow and process, and can be produced inexpensively in large numbers. No chemical alteration of the particle surface due to heat killing and staining is involved. Grazing coefficients were compared between GFP-minicells and other GFP-modified bacteria, as well as 5-(4,6-dichlorotriazinyl)aminofluorescein (DTAF)-stained cells. The grazing coefficients obtained from the removal of GFP-minicells compared favorably with estimates from tracer-independent estimates of grazing in the same experiments. Experiments with GFP-minicells resulted in community grazing coefficients similar to those reported for many different marine environments and those derived using various methods.


KEY WORDS: Bacteria · Prokaryotes · Mortality · Predation · Protist feeding · Eukaryotic microbes · Microbial predators · Size selectivity


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Cite this article as: Bochdansky AB, Clouse MA (2015) New tracer to estimate community predation rates of phagotrophic protists. Mar Ecol Prog Ser 524:55-69. https://doi.org/10.3354/meps11209

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