About Simon

As a physicist-turned-biologist, I am fascinated by how complex systems function and evolve. My main question is how interactions at one level (e.g., between genes, cells, individuals) create emergent be­havior at higher organizational levels (e.g., in genetic networks, multicellular systems, communities). I primarily work on microbial systems and use interdisciplinary methods, combining microfluidics, single-cell imaging, statistical analysis, and mathematical modeling, to create a quantitative understanding of how the properties of microbial communities emerge from intra- and interspecies interactions.

Simon van Vliet

CV

Eduction

2017Ph.D. in Systems Biology
ETH Zurich, Switzerland
2011M.Sc. Cum Laude in Applied Physics
Delft University of Technology, Netherlands
2009B.Sc. in Applied Physics
Delft University of Technology, Netherlands

Research Experience

03-2023
present
External Scientific Collaborator
University of Lausanne, Switzerland
01-2022
present
Project Leader | SNSF Ambizione Fellow 
University of Basel, Switzerland
05-2020
12-2021
Postdoc with Urs Jenal
University of Basel, Switzerland
04-2018
03-2020
Postdoc with Michael Doebeli
University of British Columbia, Vancouver, Canada
08-2017
03-2018
Postdoc with Martin Ackermann
Eawag & ETH Zurich, Switzerland
02-2013
07-2017
PhD Student with Martin Ackermann
Eawag & ETH Zurich, Switzerland
09-2012
12-2012
Visiting Researcher with Peter Galajda
Biological Research Centre, Szeged, Hungary
10-2011
09-2012
Research Associate with Juan Keymer
Delft University of Technology, Netherlands
05-2011
08-2011
Intern with Peter Galajda
Biological Research Centre, Szeged, Hungary
03-2010
04-2011
Master Thesis Student with Juan Keymer and Cees Dekker
Delft University of Technology, Netherlands
02-2008
06-2008
Bachelor Thesis Student with Teun Klapwijk
Delft University of Technology, Netherlands

PhD and Postdoc Work

Emergent behavior in two species communities

We developed an individual based model to predict how cell-cell interactions affect the dynamics of multispecies microbial communities. We showed that cells exchange metabolites over a short distance of a few cell lengths. This interaction distance can be calculated from a small number of biophysical parameters, and the value predicted by our model closely matched experimental observations. 

Read more: Dal Co et al. (2020) | Publisher | pdf

In a follow up project, we developed an analytical framework that quantitively predicts community level properties (equilibrium composition, growth rate, spatial arrangement) from these biophysical parameters. This framework thus allows us to directly link dynamics at the level of molecules to dynamics at the level of the community.

Read more: van Vliet et al. (2022) | Publisher | pdf

Multilevel selection in microbial communities

We used multilevel selection theory to study the evolutionary dynamics of host associated microbial communities. We showed that microbiomes can evolve to altruistically help their hosts, but only when stringent conditions are met. Specifically, this requires that host have relatively short generation times and strong vertical inheritance of the microbiome.

Read more: van Vliet & Doebeli (2019) | Publisher | pdf 

In a follow-up project, we developed an individual based model of free-living microbial communities and showed that multilevel selection can maintain cooperative cross-feeding interactions in multispecies communities. The degree to which cooperators can be maintained depends on the fragmentation mode of the community, and we showed that the fragmentation mode that maximizes the robustness to cheaters is an evolutionary attractor.

Read more: Henriques et al (2021) | Publisher | pdf

Cell-cell interactions in clonal populations

We studied how bacterial colonies organize their activities in space. We found that gene expression levels in bacterial micro-colonies are spatially correlated and developed an analysis method to elucidate the causes of these correlations. We showed that metabolic gradients, history-dependence, and cell-cell interactions were the main factors. Moreover, we found evidence for a novel cell-cell interaction affecting the SOS-response pathway.

Read more: van Vliet et al (2018) | Publisher | pdf

In a second project, we studied how nutrient gradients give rise to metabolic interactions and antibiotic tolerance in bacterial biofilms. We developed a microfluidic device that recreates biofilm like growth conditions within 2D bacterial populations, allowing us to measure growth rates and gene expression levels at the single cell level. We showed that cells create nutrient gradients and as a result they phenotypically differentiate. This leads to metabolic cross-feeding, antibiotic tolerance, and resilience to fluctuating environments.

Read more: Dal Co et al (2019a) | Publisher | pdf
& Dal Co et al (2019b) | Publisher | pdf