Jean-Marie Volland (Author), Arno Schintlmeister (Author), Helena Zambalos (Author), Siegfried Reipert (Author), Patricija Mozetič (Author), Salvador Espada-Hinojosa (Author), Valentina Turk (Author), Michael Wagner (Author), Monika Bright (Author)

Abstract

The giant colonial ciliate Zoothamnium niveum harbors a monolayer of the gammaproteobacteria Cand. Thiobios zoothamnicoli on its outer surface. Cultivation experiments revealed maximal growth and survival under steady flow of high oxygen and low sulfide concentrations. We aimed at directly demonstrating the sulfur-oxidizing, chemoautotrophic nature of the symbionts and at investigating putative carbon transfer from the symbiont to the ciliate host. We performed pulse-chase incubations with 14C- and 13C-labeled bicarbonate under varying environmental conditions. A combination of tissue autoradiography and nanoscale secondary ion mass spectrometry coupled with transmission electron microscopy was used to follow the fate of the radioactive and stable isotopes of carbon, respectively. We show that symbiont cells fix substantial amounts of inorganic carbon in the presence of sulfide, but also (to a lesser degree) in the absence of sulfide by utilizing internally stored sulfur. Isotope labeling patterns point to translocation of organic carbon to the host through both release of these compounds and digestion of symbiont cells. The latter mechanism is also supported by ultracytochemical detection of acid phosphatase in lysosomes and in food vacuoles of ciliate cells. Fluorescence in situ hybridization of freshly collected ciliates revealed that the vast majority of ingested microbial cells were ectosymbionts.

Keywords

microbial ecology;symbiosis;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: NIB - National Institute of Biology
UDC: 577
COBISS: 4610639 Link will open in a new window
ISSN: 1751-7362
Views: 13
Downloads: 4
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Other data

Pages: str. 714-727
Issue: ǂVol. ǂ12
Chronology: 2018
DOI: 10.1038/s41396-018-0069-1
ID: 24586348