Bacterial navigation

Chemotaxis, the ability of cells to detect and respond to a gradient in chemical concentration, plays a central role in microbial ecology, allowing cells to find nutrients, seek hosts or escape toxins. These dynamics occur at the microscale, but underpin a range of macroscale processes such as nutrient flow and remineralization rates in the ocean. We use a combination of microfluidic experiments, single cell tracking techniques, and mathematical modelling to study how different motility strategies affect the response of bacteria to transient and heterogeneous stimuli. We have been developing new microfluidic approaches to create carefully controlled spatial and temporal gradients of single or multiple chemical stimuli. These techniques enable us to directly visualize microbial motion and interactions, but also to physically sort cells according to phenotypic traits (e.g., swimming speed, chemotactic abilities). We are working on quantifying heterogeneity in chemotactic sensitivity within a microbial population using new microfluidic designs. More recently, we have been investigating how swimming speed, sensory noise and sensory adaptation impact the ability of bacteria to detect and accumulate around transient chemical sources. For more information, please contact Francesco Carrara (carraraf@ethz.ch) or Mehdi Salek (salekm@ethz.ch).