Fig. 2

Cross-sectional, whole-mount, and oblique optical section images give different views of the biofilm on kelp. N. luetkeana blades were subjected to CLASI-FISH with a probe set for the 5 major bacterial groups. A Cross-sectional image of a kelp blade embedded in methacrylate. Merged transmitted light and confocal images show the microbial biofilm on both sides of the kelp blade, with some microbial cells in the center. (i), (ii), and (iii) are enlarged images of the dashed rectangles in panel (A). Bacteroidetes rods within the autofluorescent region of kelp tissue in panel (i) fluoresce more brightly than rods in the surface biofilm and therefore appear overexposed in the image. B Whole-mount preparation imaged as a z-stack; planes 1 micrometer apart in the z dimension are shown. C Oblique optical section showing the microbial biofilm at left and kelp surface at right. Bacteroidetes rods are visible between kelp surface cells (right)