Keynote : Prof. Dr. Roeland Merks

Prof. Dr. Roeland Merks is a senior researcher at Centrum Wiskunde & Informatica (CWI), the Dutch national researcher for mathematics and computer science in Amsterdam, The Netherlands and he is a part-time full professor in Multiscale Mathematical Biology at the University of Leiden, The Netherlands. Merks received his Master of Science degree in Biology from Utrecht University, The Netherlands in 1997. After a brief research stay at Tokyo University, Japan in 1998 he pursued PhD studies in Computational Science from 1999 to 2003 the University of Amsterdam, The Netherlands. He earned his PhD for his studies with Dr. Jaap Kaandorp, Dr. Alfons Hoekstra, and Prof. Peter Sloot on the simulation of branching morphogenesis of corals. He went on to study the mechanisms of collective cell behavior during angiogenesis with Prof. James Glazier from Indiana University, Bloomington, and then moved to the VIB Dept. Plant Systems Biology in Ghent, Belgium to work on cell-based modeling of leaf morphogenesis with Dr. Gerrit Beemster and to set up his own group on plant modeling. In 2008 he moved to CWI, the Dutch national research center of mathematics and computer science, where he set up the biomodeling group of the Netherlands Consortium for Systems Biology. Merks' current research focuses on modeling angiogenesis, plant development, and mechanobiology

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Keynote title “Multiscale Modeling of the Gut Microbiota”

The human gut contains approximately 10^14 bacteria, belonging to hundreds of different species. Together, these microbial species form a complex food web that can break down food sources that our own digestive enzymes cannot handle, including complex polysaccharides, producing short chain fatty acids and additional metabolites, e.g., vitamin K. The diversity of microbial diversity is important for colonic health: Changes in the composition of the microbiota have been associated with inflammatory bowel disease, diabetes, obestity and Crohn's disease, and make the microbiota more vulnerable to infestation by harmful species, e.g., Clostridium difficile. To get a grip on the controlling factors of microbial diversity in the gut, we here propose a multi-scale, spatiotemporal dynamic flux-balance analysis model to study the emergence of metabolic diversity in a spatial gut-like, tubular environment. The model features genome-scale metabolic models of microbial populations, resource sharing via extracellular metabolites, and spatial population dynamics and evolution. In this model, cross-feeding interactions emerge readily, despite the species' ability to metabolize sugars autonomously. Interestingly, the community requires cross-feeding for producing a realistic set of short-chain fatty acids from an input of glucose, If we let the composition of the microbial subpopulations change during invasion of adjacent space, a complex and stratifed microbiota evolves, with subspecies specializing on cross-feeding interactions via a mechanism of compensated trait loss. The microbial diversity and stratification collapse if the flux through the gut is enhanced to mimic diarrhea. In conclusion, this in silico model is a helpful tool in systems biology to predict and explain the controlling factors of microbial diversity in the gut. It can be extended to include, e.g., complex food source, and host-microbiota interactions via the gut wall.