FIG. 2.

DGGE of 16S rRNA obtained from SL and ML sediment slurries following incubation with added arsenate at various salinities and compared to natural sediment samples. DGGE profiles of natural sediments are profiles of samples collected from sediment hand cores at the labeled depth intervals (in centimeters). The salinities range from 25 to 346 g liter⁻¹ and are shown after the lake. The similarities between samples are shown in an unweighted-pair group method with arithmetic mean dendrogram of Dice similarity coefficients based on band position. The scale bar indicates levels of percent similarity. The numbered bands refer to the sequences in Table S1 in the supplemental material. Open arrowheads indicate bands that match 16S rRNA gene sequences from uncultivated organisms previously discovered in ML water (see text for details). The band indicated by the solid arrowhead matches strain SLAS-3, a clone that is closely related to the halophilic As(V)-respiring strain SLAS-1 isolated previously from SL sediments (16). (DGGE profiles of natural sediments are reprinted from reference 10.)