Fig. 3.

Sulfur metabolism. a Predicted pathway for sulfate (SO₄ ²⁻) and thiosulfate (S₂O₃ ²⁻) membrane transport and cytoplasmic assimilation (black arrows) or dissimilation (gray arrows) by strain Hulk. Dashed arrows with question marks indicate reaction enzymes lacking obvious matches in the draft genome. The sulfate, thiosulfate, and sulfite (SO₃ ²⁻) anions and the sulfide (H₂S) product are boxed. Annotated ORF and Enzyme Commission (EC) numbers are shown in gray for each reaction enzyme. b-c Growth with formate and AQDS (b) or DMSO (c) as electron acceptors. The reduction of AQDS by strain Hulk turns the cultures first brown, then orange (b). The reduction of DMSO supports increases in cell numbers compared to controls without the electron donor (c). All cultures were prepared at the optimum pH and salt concentration (7 and 2%, respectively) and incubated at the optimum temperature (90 °C)