The Petri-Plater is an add-on device and software for Tecan robots. The product enables automated sample plating on Petri-dish using the "Spiral-Plating" method. In this method, the robot slowly dispenses the sample while the Petri-dish is simultaneously rotating and linearly moving on the Petri-Plater tray creating a spiral pattern on the Petri-dish. This pattern gradually spread the bacteria over the plate in a uniform and repetitive manner. Further more, by controlling the movement profile of the device the user has the flexibility to control colony spacing and dilutions across the spiral pattern, achieving better colony isolation pattern.