During the project, most effort was directed at establishing a system to work with and answer the above questions. I aimed at establishing a simplified system consisting of one algae species and one bacterial species that complement each other’s nutritional needs (what we termed a syntrophic interaction). I isolated new species of bacteria from the microalgae’s microbiome and studied how they affect the microalgae’s physiology. One of the isolates is capable of supplying vitamin B12, a vitamin that the algae cannot synthesise, and supports its growth in vitamin-deficient media. In turn, the alga’s photosynthetically fixed carbon provides organic matter to the bacterial partner to survive. We developed a microfluidic chip to be able to monitor single-cell growth of both partners in these syntrophic setting. In addition, microscopy experiments were performed to observe the behaviour of the bacteria: i.e. its swimming and attachment dynamics to the microalgae. The bacteria appear to be capable of both, but more experiments are needed to confirm preliminary observations and conclude their effect on the co-culture. After optimization of both the microfluidic chip and the visualization approach, results will be disseminated in scientific manuscripts that will be published in open access journals.
Another isolated bacterial species is capable of attachment to the microalgae by long appendages, named stalks. In this case, the attachment dynamics were easier characterized, but we are still working on understanding the effect of this association. It is not a pathogenic one, but we cannot confirm a benefit for the algae yet.
So far, the results presenting the latter system have been presented in two international scientific conferences (both in 2022): I attended the “Microbial Ocean Biophysics” international workshop (Spain, May 2022) and the Gordon Research Conference “Marine Microbes” (Switzerland, June 2022). I have also participated in outreach activities to promote marine microbiology to children and teenagers: I participated in the planning and organization of a scientific workshop about marine microbes for teenagers, as part of the outreach event Scientifica (September 2021), organized by ETH and UHZ. I also co-led and presented a laboratory activity on marine phytoplankton and light microscopy to schoolgirls as part of the event Kangaroo goes Science (June 2022), organized by the Kangaroo Switzerland Association.
