In 1926, when he was almost 50, Kahl published a paper in which he identified, classified, and described hundreds of new species of protists.
Although this particular combination of organisms is unique, symbiotic interactions “are very widespread, in any sort of aquatic ecosystem,” says Matthew Johnson, a protist ecologist at the Woods Hole Oceanographic Institute in Massachusetts who did not participate in the study.
Researchers have suggested that the ancestor of mitochondria could have been a purple bacterium, he explains, but there was only a single study from 1993 that looked at purple bacteria in eukaryotes.
tenue because, as an undergrad at the University of Bonn in Germany, he’d seen a 2006 book with color photos and scanning electron micrographs of microscopic organisms found in the Simmelreid moorland by independent microscopist Martin Kreutz and organismal biologist Wilhelm Foissner, then a biologist at the University of Salzburg in Austria.
tenue samples to Dalhousie University, Hess—by then a group leader at the University of Cologne in Germany—invited Muñoz-Gómez to come to Germany and study the ciliate there, where they wouldn’t have to navigate shipping them long distances.
tenue’s purple bacterium is most closely related to members of the genus Thiodictyon, which uses bacteriochlorophyll as a photosynthetic pigment and also metabolizes sulfur to use as an electron donor for photosynthesis.
“We have some very plausible hypotheses based on genome data on microscopic observations of how the ciliate likes to live or which environments it prefers, but we want to acquire more experimental data about the kind of molecules that the symbionts are exchanging between them,” explains Muñoz-Gómez.
“Actually being able to grow them in the lab and therefore doing rigorous testing in different conditions having more environmental samples so that you can test different environmental conditions within the samples would be different ways to go about it,” she explains.
The nature of the relationship between the three organisms remains an open question.