Automating picoplankton sample analysis
Plankton are by far the most abundant inhabitants of the world's oceans and they play an important role in the cycling of nitrogen, carbon and other species. Yet little is known about them. While epifluorescence microscopy has been instrumental in the characterisation of plankton, the process is time-consuming. Fortunately, scientists with the Max Planck Institute for Marine Microbiology have come up with an automated system for sample analysis. The work was performed in the context of the BASICS project, funded in part by the Fifth Framework Programme. More specifically, samples are examined for the presence of picoplankton with the aid of fluorescence in situ hybridization (FISH) and DNA staining. Two nested walk paths assist the microscope to traverse the samples until the requisite number of cells has been studied. The German microbiologists addressed problems associated with refocusing by implementing a backup autofocusing routine. By outfitting the microscope with a motorized drive, shutters and wheels, the need for a human operator is eliminated. Sample analysis time is further reduced with the inclusion of advanced image capture and processing capabilities. The system was put to the test during the BASICS project with samples collected from the North Sea. Remarkably, twenty-eight samples were analysed within a four-hour period. This development will help speed the classification of picoplankton and hence our understanding of these petite yet important inhabitants of the Earth's biosphere.
