Stable carbon isotope fractionations of the hyperthermophilic crenarchaeon Metallosphaera sedula

Abstract

The stable carbon isotopic compositions of the inorganic carbon source, bulk cell material, and isoprenoid lipids of the hyperthermophilic crenarchaeon Metallosphaera sedula, which uses a 3-hydroxypropionate-like pathway for autotrophic carbon fixation, have been measured. Bulk cell material was approximately 3‰ enriched in 13C relative to the dissolved inorganic carbon, and 2‰ depleted in 13C relative to isoprenoid membrane lipids. The isotope data suggested that M. sedula uses mainly bicarbonate rather than CO2 as inorganic carbon source, which is in accordance with a 3-hydroxypropionate-like carbon fixation pathway. To the best of our knowledge this is the first report of 13C fractionation effects of such a hyperthermophilic crenarchaeon.