Chemotaxis, growth, and interspecies interactions using the in situ chemotaxis assay

We address how bacterial chemotaxis toward phytoplankton metabolites and their subsequent catabolism influences assembly in simple two-species model communities using the in situ chemotaxis assay (ISCA). To this end, we measured the individual chemotactic strengths and growth rates of seven bacterial strains (previously isolated from coastal seawater enriched with phytoplankton exometabolites in response to representative phytoplankton metabolites: dimethylsulfoniopropionate (DMSP) spermidine, 2,3-dihydroxypropane-1-sulfonate (DHPS), trimethylamine (TMA), xylose, ectoine, glutamate, glycolate, isethionate, ribose. We then mimicked the early phase of bacterial community establishment in metabolite hotspots by conducting experiments with pairs of bacterial species and monitoring subsequent community composition following chemotaxis and growth on these metabolites,