Abstract

Droplet-based single-cell culture coupled with smartphone imaging for portable and rapid bacteria quantification

Bo Ma, Professor, Chinese Academy of Sciences

For quantification of viable bacteria, standard plate count (SPC) have been widely used and is still recognized as the golden method. However SPC can take several days to complete due to the requirement to grow individual cell into a visible colony, which hinders rapid bacteria enumeration. In microdroplets, growth from a single bacterial cell can result in optical difference which means the viable bacterial count can potentially be measured only after several bacterial doubling cycles. Here, a droplet based rapid single cell culture method was proposed, and a portable platform for rapid bacterial enumeration, which integrates a power free single-cell droplet generator with a smartphone-based imaging setup based on turbidity difference originated from cell growth within droplets, was developed. As a concept-of-proof demonstration, Escherichia coli samples were quantified on the developed platform in less than 6 hours. Moreover no significant difference was observed between the smartphone-based droplet counting and the SPC method. The low cost and portability of the developed platform should enable or facilitate culture-based rapid bacterial enumeration in infield applications and circumstances especially in low resource regions.