Light-diffractive patterning of Porphyridium purpureum

Light guidance is a convenient and versatile way to control the positions of phototactic microorganisms. However, the illumination strategies require adaption to the respective organism. We report on the generation of structures composed of the gliding and exopolysaccharide-secreting algae Porphyridium purpureum via their photomovement. Light patterns from a two-dimensional computer-generated hologram were projected onto inoculated agar plates. The obtained pixelated algae patterns were evaluated with regard to the illuminated intensity, contrast and pixel size. Upper and lower thresholds for algae accumulation were determined, allowing to enhance future manipulation of phototactic microorganisms.