Postdoctoral position in “Microbial chemotaxis at the continental scale" in Zürich

The Environmental Microfluidics Group of Prof. Roman Stocker at the Institute of Environmental Engineering at ETH Zurich is seeking a dynamic and motivated postdoctoral researcher with expertise in environmental microbiology and field-based experiments to quantify microbial behaviour in the marine environment as part of , a large expedition sampling European coastlines. This postdoctoral position is for three years.

Understanding how organisms forage within a heterogeneous resource landscape is a fundamental goal of ecology. Within the ocean, populations of microorganisms govern marine productivity and biogeochemical cycling over vast, ocean basin scales. However, from the perspective of an individual planktonic microbe, important ecological processes including resource acquisition, predation and symbiosis, occur over microscopic scales, often within a surprisingly heterogeneous seascape shaped by microscale gradients of chemical resources and foraging cues. Evidence from theoretical and laboratory-based studies indicate that some marine microbes are highly adept at foraging within patchy environments using chemotaxis – the ability to migrate up or down chemical gradients – and that these behaviours have important ecological and biogeochemical implications.

Microbial chemotaxis plays important roles in the oceanic water column, allowing bacteria to exploit localized nutrient hotspots, colonize particles or establish associations with other microorganisms. Although the role of chemotaxis in marine systems has been explored extensively in model systems within laboratory settings, it was impossible until very recently to study this behaviour in the ocean. To address this issue, we have developed the In Situ Chemotaxis Assay (ISCA), the first platform allowing to interrogate of microbial behaviour in the environment. Over the past six years, we have successfully used this microfluidic device to characterize chemotaxis in the field, opening the door to the systematic interrogation of this microbial behaviour over much larger spatial scales.

The focus of this postdoctoral position will be to quantify and characterize chemotactic behaviour in situ as part of the (Traversing European Coastlines) expedition. This expedition, conducted by the Tara Ocean Foundation, Tara Oceans Consortium, and EMBL, will carry out land-sea transects (sampling soil, sediments, shallow waters, and oceanic waters in parallel at each site) to study coastal interfaces at 120 sites in Europe. You will deploy ISCAs to characterize chemotaxis towards ecologically relevant molecules at selected sites. In addition, you will work with the shallow water sampling team and deploy ISCAs in the marine environment. You will then quantify the strength of chemotaxis towards each molecule tested using flow cytometry, to determine the taxonomy and genomic characteristics of the chemotactic microorganisms using molecular approaches (amplicon sequencing, metagenomics). Furthermore, you will leverage the large amount of contextual data collected by the other teams to pinpoint environmental drivers influencing the strength of chemotaxis. By bringing field and laboratory expertise in environmental microbiology, you will considerably advance our understanding of microbial chemotaxis in the ocean at scales never attempted before, with opportunities for collaborations and co-authorship in publications through the TREC expeditions.

• You have a strong background in microbial ecology, with both laboratory and field experience, and are keen to be part of a large sampling expedition
• You want to work in a highly interdisciplinary environment at the interface between microbial ecology, genomics and biophysics
• Through this project, you will have the opportunity to work in a cutting-edge, fast-paced research environment, to interact with experts in many different disciplines, and to learn about behavioural, biophysical and ecological processes shaping the life of the oceans
• Your ability to work independently, come up with creative and innovative solutions, communicate clearly and work collaboratively with the TREC sampling teams will be fundamental

ETH Zurich is a family-friendly employer with excellent working conditions. You can look forward to an exciting working environment, cultural diversity and attractive offers and benefits.