Impact of molecular hydrogen on chalcopyrite bioleaching by the extremely thermoacidophilic archaeon Metallosphaera sedula

Abstract

Hydrogen served as a competitive inorganic energy source, impacting the CuFeS(2) bioleaching efficiency of the extremely thermoacidophilic archaeon Metallosphaera sedula. Open reading frames encoding key terminal oxidase and electron transport chain components were triggered by CuFeS(2). Evidence of heterotrophic metabolism was noted after extended periods of bioleaching, presumably related to cell lysis.

FIG. 1.

Chalcopyrite bioleaching by M. sedula. (A) Nine days postinoculation, chalcopyrite bioleaching by M. sedula exposed to an air headspace (1-Mse) is visually evident compared to its abiotic control (1-ac). No obvious evidence of bioleaching is visible for M. sedula grown in a hydrogen-containing headspace (2-Mse) or the associated abiotic control (2-ac). (B) Total soluble iron (mg/liter, measured as a function of hours postinoculation) is significantly higher in cultures containing M. sedula grown in a hydrogen-containing headspace than the abiotic control, indicating active bioleaching. Typical standard deviations of <10 mg/liter were found for the iron assay (n = 3 for abiotic controls; n = 9 for M. sedula cultures).

FIG. 2.

Heat plot of electron transfer components involved with oxidation of Fe(II) and RISCs. Heat plots were compiled using Array File Maker 4.0 (6). Red indicates levels of high transcription, black indicates average transcription (set to an LSM [least squares mean of normalized log₂ transcription levels] of 0), and green indicates levels of low transcription, for M. sedula ORFs in the inoculum (d0), at 3 days of growth on CuFeS₂ (d3), and at 9 days of growth on CuFeS₂ (d9).