Funded by:

FWF research project P24565-B22 Thiotrophic ciliate mutualism between Cand. Thiobios zoothamnicoli and Zoothamnium niveum – cooperation goes empirical


In the frame of a three years project focusing on the thiotrophic symbiotic model Zoothamnium niveum, we spent one month in the marine biology station of the Slovenian “National Institute of Biology” in the city of Piran. This was the second field trip of our newly started project “TioCiM”. We performed a first set of experiments in the frame of the hypotheses 1, 2 and 3 of our project.


Hypothesis 1: Cand. Thiobios zoothamnicoli is a facultative, polyclonal symbiont

Objective of the stay: Sampling the symbiotic ciliate Zoothamnium niveum for population genetic analyses.


Hypothesis 2: Symbionts gain energy through oxidation of reduced sulfur species to fix inorganic carbon

Objective of the stay: Performing pulse/chase experiments with 14C bicarbonate for further autoradiography analyses with freshly collected colonies.


Hypothesis 3: Host is nourished by free-living microbes through digestion and by symbionts through release and digestion

Objective of the stay: Cultivating the ciliate under different conditions (normoxic, optimal, axenic, non axenic) and incubate it afterward with 14C bicarbonate for further autoradiography analyses. The digestion process in the host cells will be studied by cytochemical detection of two lysosomal enzymes.


Master Thesis

During this stay, Judith Drexel collected samples and performed experiments for her Master thesis. collection and experiments. Judith’s work aims at following the decrease of symbionts during normoxic incubations under flow through and stagnant conditions. The samples then will be studied using SEM.



Judith Drexel

Salvador Espada Hinojosa

Ingrid Kolar

Jean-Marie Volland


International Collaborations

This research stay was also the opportunity for us to initiate two collaborations with scientists from the Piran Marine Biology Station. The 14C bicarbonate incubations were conducted in collaboration with Patricija Mozetic and Valentina Turk. Moreover, we were collaborationg with Branko Cermelj and Neli Glavas in order to characterize the microenvironment of the ciliates using H2S, O2 and pH microsensors.



From the left to the right: Judith, Salvador, Jean-Marie and Ingrid



The ciliate colonies growing on a sunken wood


Judith working on her master thesis


The sampling of the ciliates!