Effects of hydrophobic and electrostatic cell surface properties of bacteria on feeding rates of heterotrophic nanoflagellates.
The influence of cell surface hydrophobicity and electrostatic charge of bacteria on grazing rates of three common species of interception-feeding nanoflagellates was examined. The hydrophobicity of bacteria isolated from freshwater plankton was assessed by using two different methods (bacterial adhesion to hydrocarbon and hydrophobic interaction chromatography). The electrostatic charge of the cell surface (measured as zeta potential) was analyzed by microelectrophoresis. Bacterial ingestion rates were determined by enumerating bacteria in food vacuoles by immunofluorescence labelling via strain-specific antibodies. Feeding rates varied about twofold for each flagellate species but showed no significant dependence on prey hydrophobicity or surface charge. Further evidence was provided by an experiment involving flagellate grazing on complex bacterial communities in a two-stage continuous culture system. The hydrophobicity values of bacteria that survived protozoan grazing were variable, but the bacteria did not tend to become more hydrophilic. We concluded that variability in bacterial cell hydrophobicity and variability in surface charge do not severely affect uptake rates of suspended bacteria or food selection by interception-feeding flagellates.
Matz
C
C
Department of Physiological Ecology, Max Planck Institute for Limnology, D-24302 Plön, Germany. matz@mpil-ploen.mpg.de
Jürgens
K
K
D000818:Animals; D001419:Bacteria / Q000254:growth & development; D018407:Bacterial Physiological Phenomena; D003470:Culture Media; D056890:Eukaryota / Q000502:physiology*; D005247:Feeding Behavior / Q000502:physiology*; D005618:Fresh Water / Q000382:microbiology / Q000469:parasitology; D055672:Static Electricity; D013499:Surface Properties
D003470:Culture Media