Images of materials, growth compartments, and microbial culture on chips. (A) SEM of aluminum oxide showing pores on average 200 nm diameter. (B) Transmission light microscopy of hundreds of 20 × 20-μm compartments viewed from above. (C) SEM of 7 × 7-μm compartments from above at a 30° angle. (D) Culture of L. plantarum in six compartments of the same dimensions as C stained with a fluorogenic dye (Syto 9) after growth and imaged from above. (E) Detection of β-galactosidase activity using the fluorogenic substrate FDG, from E. coli containing plasmid pUC18 grown in a 20 × 20-μm compartment. (F) As in E with one plasmid-containing microcolony, viewed at lower magnification. (G) View of 20 × 20-μm format chip with one area supporting a GFP-expressing strain of E. coli in a background of nonfluorescent cells. (H) Previously uncultivated oligotrophic bacterium related to Dechloromonas sp. labeled by FDP metabolism and grown in a 20 × 20-μm compartment supplied by Rhine water, before recovery and identification by PCR.