Plate reader assays acess global fluorescence level, but that excludes the possibility from single cell analysis. Flow citometry partially solves this problem, by getting a population measurement, with each cell being assigned a data point regarding its fluorescence and criteria such as the "complexity" of cells, measured by the side scatter of the light, and cell size, by the forward scatter of the light. However, it is possible to characterize fluorescence even better: by using microscopy!
FLuorescence microscopy is a resource that is widely available in research facilities, due to its versatility. It can be used for pratically every field of biological analysis, from tissues, to eukaryotic cell cultures and, of course, to bacteria! It is possible to get all the measurements feasible for the flow citometry, but with the bonus of getting data about cell morphology, clumping, and general health of cells. And they can be analysed by open plugins, such as the ones present in ImageJ.
Even though it was not feasible to process the InterLab samples this way in the team busy schedule, we did analyse microscopy images of P. agglomerans that way. Check it on our detection page! We hope you will feel inspired by this early slidedeck and image analysis and further expand this tool for the Interlab study!