Millifluidic droplet analyser for microbiology

Abstract

We present a novel millifluidic droplet analyser (MDA) for precisely monitoring the dynamics of microbial populations over multiple generations in numerous (≥10³) aqueous emulsion droplets (∼100 nL). As a first application, we measure the growth rate of a bacterial strain and determine the minimal inhibitory concentration (MIC) for the antibiotic cefotaxime by incubating bacteria in a fine gradient of antibiotic concentrations. The detection of cell activity is based on the automated detection of an epifluorescent signal that allows the monitoring of microbial populations up to a size of ∼10⁶cells. We believe that this device is helpful for the study of population dynamic consequences of microbe-environment interactions and of individual cell differences. Moreover, the fluidic machine may improve clinical tests, as it simplifies, automates and miniaturizes the screening of numerous microbial populations that grow and evolve in compartments with a finely tuned composition.