Fig 1.
Sampling area from the Gorleben halite in a depth of 840 m within the Knäulsalz layer.
Fig 2.
Phylogenetic dendrogram (neighbor-joining method) of Brachybacterium sp. G1 and its closest phylogenetic relatives based on an alignment of 16S rRNA gene sequences (aligned with ClustalX-MEGA 6.06).
GenBank accession numbers are shown in brackets.
Fig 3.
Growth of Brachybacterium sp. G1 as a function of ionic strength and salt composition.
Circles indicate NaCl containing media, squares indicate the addition of MgCl2.
Fig 4.
Bioassociation studies with Brachybacterium sp. G1 and uranium (pCH+ 6, 1.7 M NaCl). a) Time-dependent association with different dry biomass and uranium concentrations, b) comparison to H. noricense (3 M NaCl, 0.5 mg/mL DBM) [11] at 40 μM, c) dry biomass dependent study [U(VI)] = 20 μM).
Fig 5.
Micrographs of Brachybacterium sp. G1 incubated with and without uranium (20 μM U, pCH+ 6, 1.7 M NaCl) a) Fluorescence microscopy images of live/dead stained cells (green fluorescence–alive, red fluorescence– dead), b) Electron microscopy images (secondary electrons), c) Mapping of organic elements (orange, C, N, O) and uranium (blue). Scale bar on SEM images is 5 μm. SEM images are enlarged in SI (S2 Fig).
Fig 6.
a) In situ ATR FT-IR difference spectra of U(VI) sorption on Brachybacterium sp. G1 cells ([U(VI)] = 40 μM, pCH+ 6, 1.7 M NaCl). The “Equilibration” spectrum confirms a stable bacterial film on the ATR crystal. “U(VI)—sorption” spectra were recorded at different times after induction of U(VI) association. “Flushing” shows the reversibility. b) For comparison the spectrum of U(VI) bioassociation on H. noricense cells after 120 min ([U(VI)] = 40 μM, pCH+ 6, 3 M NaCl) [11].
Table 1.
Tentative assignment of infrared bands observed in difference spectra of in situ ATR FT-IR with H. noricense DSM15987T ([U(VI)] = 40 μM, [NaCl] = 3 M, pCH+ 6) [11] and Brachybacterium sp. G1 ([U(VI) = 40 μM, [NaCl] = 1.7 M, pCH+ 6).