FIG. 2.

Discrimination of nirK-type denitrifiers and nondenitrifiers in mixtures of pure cultures by RING-FISH. Denitrifier cells were hybridized with nirK polynucleotide probes, and nondenitrifiers were counterstained by FISH using Cy3-labeled oligonucleotide probes. (A to C) Mixture of the denitrifier A. xylosoxidans NCIMB 11015 and the nondenitrifier B. pumilus DSM 27. (D to F) Mixture of the denitrifier A. xylosoxidans NCIMB 11015 and the nondenitrifier H. zavarzinii ZV-580. The organisms were labeled with fluorescein after RING-FISH (A and D) and with Cy3 after FISH (B and E). Panels C and F are phase-contrast images. Bars = 10 μm.