FIG. 1.

Dot blot hybridization and ARDRA of 16S rDNA clones. Three hundred fifty-three clones were screened by dot blot hybridization with different probes. The diversity within each group was further investigated by ARDRA with one restriction endonuclease (HaeIII). The filled bars represent the numbers of clones detected with specific probes, and the open bars show the numbers of different ARDRA patterns after digestion with HaeIII. Probe GP is specific for gram-positive bacteria (28), ALF968 is specific for members of the α subclass of Proteobacteria (35), CF319 is specific for the Cytophaga-Flavobacterium group (30), Gamma598 targets three gene clusters affiliated with sulfur-oxidizing bacteria in the γ subclass of Proteobacteria, Sval428 is specific for psychrophilic sulfate reducers isolated from the same site (48), probe 660 targets Desulfobulbus species (5), 687 is specific for Desulfovibrio and some species of Geobacteraceae (5), and 804 targets Desulfobacter, Desulfobacterium, and Desulfobotulus species (5). “EUB338 only” indicates the clones which hybridized only with the universal eubacterial probe (1). No EUB338 signal describes clones with a correctly sized insert of 1.5 kb but no hybridization signal at all.