A fundamental study on nickel isotope fractionation during growth of methanogenic archaea

Abstract

Bioactive heavy metals are potential environmental factors for microbial activity in the deep subseafloor environment. To examine the bioavailability of heavy metals by subseafloor microorganisms, we cultured methanogenic archaea and investigated the isotopic fractionation of nickel (Ni), which is essential for the activity of methanogens. To address the differences between culture conditions in the laboratory and the actual subseafloor environment, we cultured Methanosarcina barkeri under multiple conditions by varying 1) the methanogenic pathway, 2) the dissolved Ni concentration in the growth medium, and 3) the growth rate (temperature), and analyzed the Ni isotope composition in the growth medium before and after cultivation and in the methanogen cells after cultivation.