Giant ciliate mutualism response to variable abiotic environment

H₂S plays a central role in the nutritional interactions of thiotrophic Cand. Thiobios zoothamnicoli and the colonial ciliate Zoothamnium niveum. Fitness is coupled between mutualistic partners according to H₂S concentration (i.e. all forms of dissolved sulfide). H₂S is notoriously instable and follows annual cycles in temperate waters. How fidelity between partners is maintained during the cold season when H₂S is lacking is unknown.

Aims: We aim to reveal the survival strategy of this mutualism during lack of H₂S over the annual cycle. We propose to perform re-infection and encystment experiments to assess the molecular response.

Approach: We will apply metatranscriptomics, measurements of activity and fitness-related traits using incorporation of BrdU for host, and the cell cycle protein FtsZ for symbiont fitness, lipid and protein biosynthesis using BONCAT and click chemistry, and stable isotope probing with heavy water and Raman spectroscopy.

Relevance: This project will unravel the maintenance and microbe – host interactions of the mutualism over a one-year period.

Student: Teresa Maria Rosa Winter

Faculty: Bright (PI), Wagner, Bulgheresi, Rattei

Funding: FWF doc.fund project MAINTAIN

Selected publications:

Volland, J.-M., Schintlmeister, A., Zambalos, H., Reipert, S., Mozetič, P., Espada-Hinojosa, S., Turk, V., Wagner, M. & Bright, M. NanoSIMS and tissue autoradiography reveal symbiont carbon fixation and organic carbon transfer to giant ciliate host. ISME J. 12, 714–727 (2018).

Le Bris, N., Rodier, P., Sarradin, P.-M. & Le Gall, C. Is temperature a good proxy for sulfide in hydrothermal vent habitats? Cah. Biol. Mar. 47, 465–470 (2006).

Rinke, C., Lee, R., Katz, S. & Bright, M. The effects of sulphide on growth and behaviour of the thiotrophic Zoothamnium niveum symbiosis. Proc. Biol. Sci. 274, 2259–2269 (2007).

Bright, M., Espada-Hinojosa, S., Lagkouvardos, I. & Volland, J.-M. The giant ciliate Zoothamnium niveum and its thiotrophic epibiont Candidatus Thiobios zoothamnicoli: a model system to study interspecies cooperation. Front. Microbiol. 5, 145 (2014).

Nedwell, D. B. & Floodgate, G. D. The effect of microbial activity upon the sedimentary sulphur cycle. Mar. Biol. 16, 192–200 (1972).