Biofilm development of the S. oneidensis luxS mutant and the WT control strain. Biofilms of both strains were grown on glass surfaces, which were placed in Petri dishes filled with SDM. At each time point, a glass slide was removed from the Petri dish and used for microscopic investigation. The pictures are selected from 2-5 records. Up to 9 h of growth, 2 D images from the fluorescence microscope were recorded with 40 × magnification, and these showed no difference between the two strains. After 19 h of growth, 3 D images could be recorded by Confocal Laser Scanning Microscopy. From 19 h until the end of the experiment, the luxS mutant formed a less-differentiated, loosely-bound biofilm, and the WT control tended to gather into tight clusters.